M. Movahedi Rad

57212508880

Publications - 115

Evaluation of early warning signals for soil erosion using remote sensing indices in northeastern Iran

Babak Naimi Mohsen Hosseinalizadeh Narges Kariminejad Abdolhossein Boali M. Movahedi Rad Vahid Shafaie Hamid Reza Asgari Ali Mohamadian Behbahani

Publication Name: Scientific Reports

Publication Date: 2025-12-01

Volume: 15

Issue: 1

Page Range: Unknown

Description:

Soil erosion represents a major challenge to natural resource conservation, causing land degradation, biodiversity loss, and diminished soil quality. This study explored the use of satellite imagery to evaluate the spatiotemporal risk of soil erosion in northeastern Iran. The ICONA model was applied to identify areas at severe erosion risk, while remote sensing indices (NDVI, NDSI, and TGSI) were employed to analyze erosion trends. NDVI is used to monitor vegetation health, NDSI detects soil salinity levels, and TGSI assesses topsoil grain size distribution, collectively providing critical insights into soil erosion risk in the study area. These indices, derived from the Google Earth Engine with a 30-meter spatial resolution and monthly temporal intervals (2003–2022), were assessed at 100 points, equally divided between eroded and non-eroded regions. Field data, including vegetation plots and soil profiles, were used to validate the remote sensing outputs. Early warning signals were analyzed through three statistical indices—autocorrelation coefficient, skewness, and standard deviation—using Kendall’s tau. Results revealed that 39.7% of the area falls under low erosion risk, 58.4% under medium risk, and 1.9% under severe risk. Significant breakpoints in NDSI and NDVI were identified in 2013, while TGSI showed no detectable change. Major shifts occurred near the Alagol, Almagol, and Ajigol wetlands and northern drylands. This study underscores the importance of integrating satellite data with field validation to improve soil management, protect biodiversity, and guide sustainable erosion mitigation strategies.

Open Access: Yes

DOI: 10.1038/s41598-025-94926-x

Automated elasto-plastic design of truss structures based on residual plastic deformations using a geometrical nonlinear optimization framework

M. Movahedi Rad Péter Grubits

Publication Name: Computers and Structures

Publication Date: 2025-09-01

Volume: 316

Issue: Unknown

Page Range: Unknown

Description:

This paper introduces a novel automated framework for the optimal design of steel truss structures, incorporating plastic deformations through the complementary strain energy of residual forces while minimizing weight. The presented methodology is equally applicable to purely elastic scenarios, ensuring zero plastic deformations and further reducing material usage. To achieve this, a nonlinear finite element (FE) program was developed, capable of accounting for large deformations and initial geometric imperfections. A genetic algorithm (GA) was integrated to iteratively optimize the objective function, enabling a fully automated design process. The efficiency and versatility of the framework were validated through four numerical examples. The first two comprise benchmark cases: a 9-bar planar truss and a 25-bar space truss. The remaining two examples were selected to be more representative of practical applications, involving a prestressed arched truss and a double-layer space truss. Analyses of various configurations were performed to demonstrate the robustness of the approach. Using the proposed methodology, significant improvements in plastic performance and material efficiency were achieved, underscoring its potential, adaptability, and effectiveness in advancing truss design techniques.

Open Access: Yes

DOI: 10.1016/j.compstruc.2025.107855

On critical pounding mechanism of base-isolated buildings using an optimized multi-hazard method

Denise Penelope N. Kontoni Nashwan Adnan Othman Ali Majdi M. Movahedi Rad Muhannad Riyadh Alasiri Saiful Islam Ataallah Sadeghi-Movahhed

Publication Name: Results in Engineering

Publication Date: 2025-09-01

Volume: 27

Issue: Unknown

Page Range: Unknown

Description:

In many studies on the effect of pounding on isolated structures, the failure to consider all potential pounding scenarios, including floor-to-floor (FF), floor-to-column (FC), and pounding with a moat wall, can introduce uncertainty into the obtained results. Therefore, this study investigates the critical pounding scenarios in isolated structures subjected to seismic excitations. Three primary types of pounding are examined: FF, FC, and MW, under both two-sided and one-sided limitations. Additionally, the study investigates the effects of varying gap sizes and structural heights on the response of structures subjected to each pounding type. In the FF and FC scenarios, six-story and nine-story base-isolated buildings are analyzed in relation to adjacent six-story fixed-base structures. The endurance time method is employed to obtain the seismic responses of the structures. The results indicate that FC pounding consistently induced the highest shear forces in the columns and represented the most critical failure mode. The base-isolated structures that are significantly taller than adjacent fixed-base structures (e.g. 9.6 m) are more susceptible to damage compared to those with similar heights to their neighbors. Furthermore, increasing the gap size can lead to a 100 % rise in inter-story drift under two-sided FF pounding and a 126 % increase in column shear force under two-sided FC pounding.

Open Access: Yes

DOI: 10.1016/j.rineng.2025.106533

A Nonlinear Computational Framework for Optimizing Steel End-Plate Connections Using the Finite Element Method and Genetic Algorithms

M. Movahedi Rad Péter Grubits Tamás Balogh

Publication Name: Algorithms

Publication Date: 2025-08-01

Volume: 18

Issue: 8

Page Range: Unknown

Description:

The design of steel connections presents considerable complexity due to their inherently nonlinear behavior, cost constraints, and the necessity to comply with structural design codes. These factors highlight the need for advanced computational algorithms to identify optimal solutions. In this study, a comprehensive computational framework is presented in which the finite element method (FEM) is integrated with a genetic algorithm (GA) to optimize material usage in bolted steel end-plate joints, while structural safety is ensured based on multiple performance criteria. By incorporating both material and geometric nonlinearities, the mechanical response of the connections is accurately captured. The proposed approach is applied to a representative beam-to-column assembly, with numerical results verified against experimental data. By employing the framework, an optimized layout is obtained, yielding a (Formula presented.) improvement in the overall performance objective compared to the best-performing validated model and a (Formula presented.) reduction in material volume relative to the most efficient feasible alternative. Furthermore, a (Formula presented.) decrease in equivalent plastic strain is achieved compared to the configuration exhibiting the highest level of inelastic deformation. These findings demonstrate that the developed method is capable of enhancing design efficiency and precision, underscoring the potential of advanced computational tools in structural engineering applications.

Open Access: Yes

DOI: 10.3390/a18080460

Performance of Concrete Incorporating Waste Glass Cullet and Snail Shell Powder: Workability and Strength Characteristics

M. Movahedi Rad Akindele Christopher Apata Udeme Udo Imoh

Publication Name: Buildings

Publication Date: 2025-07-01

Volume: 15

Issue: 13

Page Range: Unknown

Description:

This study investigates the combined use of waste glass cullet (WGC) and snail shell powder (SSP) as a sustainable binary cementitious system to enhance the mechanical performance and durability of concrete, particularly for rigid pavement applications. Nine concrete mixes were formulated: a control mix, four mixes with 5%, 10%, 15%, and 20% WGC as partial cement replacement, and four corresponding mixes with 1% SSP addition. Slump, compressive strength, and flexural strength were evaluated at various curing ages. Results showed that while WGC reduced workability due to its angular morphology (slump decreased from 30 mm to 20 mm at 20% WGC), the inclusion of SSP slightly mitigated this reduction (21 mm at 20% WGC + 1% SSP). At 28 days, compressive strength increased from 40.0 MPa (control) to 45.0 MPa with 20% WGC and further to 48.0 MPa with the addition of SSP. Flexural strength also improved from 7.0 MPa (control) to 7.8 MPa with both WGC and SSP. These improvements were statistically significant (p < 0.05) and supported by correlation analysis, which revealed a strong inverse relationship between WGC content and slump (r = −0.97) and strong positive correlations between early and later-age strength. Microstructural analyses (SEM/EDX) confirmed enhanced matrix densification and pozzolanic activity. The findings demonstrate that up to 20% WGC with 1% SSP not only enhances strength development but also provides a viable, low-cost, and eco-friendly alternative for producing durable, load-bearing, and sustainable concrete for rigid pavements and infrastructure applications. This approach supports circular economic principles by valorizing industrial and biogenic waste streams in civil construction.

Open Access: Yes

DOI: 10.3390/buildings15132161

Slant shear tests and fuzzy logic integration for evaluating shear bond strength in SCC and FRSCC repair applications

Amin Ghodousian Oveys Ghodousian M. Movahedi Rad Vahid Shafaie Mahdi Homayounfar

Publication Name: Case Studies in Construction Materials

Publication Date: 2025-07-01

Volume: 22

Issue: Unknown

Page Range: Unknown

Description:

This study examines the interfacial bond characteristics of twenty mix proportions, comprising ten self-compacting concrete (SCC) and ten fiber-reinforced self-compacting concrete (FRSCC) formulations, the latter enhanced with 0.1 % polypropylene fibers for repair applications. Initially, experiments such as slump flow, 28-day compressive strength, and tensile strength tests were conducted to evaluate the mechanical properties of the repair layers intended for use in slant shear tests. The primary focus of the research then shifted to determining shear bond strength (SBS) and calculating interfacial cohesion and friction angles using slant shear tests across various inclination angles on these mix proportions applied over a normal vibrated concrete (NVC) substrate. Notably, FRSCC mixtures with 10 % microsilica exhibited notable enhancements, showing increased cohesion of 8.28 MPa and a tensile strength increase of 24.50 % compared to their SCC counterparts. Additionally, a general trend was observed where FRSCC mixtures demonstrated higher cohesion values compared to SCC, underscoring the effectiveness of fiber reinforcement. Furthermore, the research introduces a novel predictive model employing a fuzzy system with a generalized Mamdani's interference engine and Hamacher family of t-norms to accurately predict the SBS, achieving a predictive accuracy with an R2 value up to 0.94. Employing the fuzzy model, characterized by its high predictive accuracy, can significantly reduce the frequency of experimental tests required in the field, thereby lowering construction testing costs and enhancing repair efficiency. These findings not only advance our understanding of SCC and FRSCC behaviors in repair scenarios but also contribute significantly to the development of more reliable and sustainable construction practices by improving the precision of SBS predictions in theoretical modeling and empirical testing.

Open Access: Yes

DOI: 10.1016/j.cscm.2024.e04176

Dem-driven investigation and AutoML-Enhanced prediction of Macroscopic behavior in cementitious composites with Variable frictional parameters

M. Movahedi Rad Vahid Shafaie

Publication Name: Materials and Design

Publication Date: 2025-06-01

Volume: 254

Issue: Unknown

Page Range: Unknown

Description:

This study presents a numerical investigation and predictive modeling framework to evaluate the influence of microscale frictional parameters on the mechanical behavior and failure mechanisms of cementitious composites. In the first phase, discrete element modeling (DEM) was employed to analyze the effects of bonded friction angle and non-bonded friction coefficient on the stress–strain response, failure evolution, and macro-scale properties. The results revealed a distinct transition from tensile to shear-dominated failure modes beyond a critical friction angle, accompanied by notable changes in compressive strength and deformation characteristics. Additionally, the role of non-bonded friction coefficient in post-failure behavior was identified, emphasizing its influence on load-redistribution. In the second phase, an AutoML-driven artificial neural network (ANN) was optimized via grid search, selecting an optimal four-layer model to predict macroparameters from microscale DEM inputs. The proposed ANN demonstrated high predictive accuracy, effectively capturing nonlinear dependencies while significantly reducing the need for additional numerical simulations. This integration of DEM and AI-based predictive modeling provides a computationally efficient, scalable solution for material characterization, enabling faster, data-driven insights into cementitious composite behavior without reliance on extensive simulation campaigns.

Open Access: Yes

DOI: 10.1016/j.matdes.2025.114069

Analysis and Prediction of Traffic Conditions Using Machine Learning Models on Ikorodu Road in Lagos State, Nigeria

M. Movahedi Rad Udeme Udo Imoh

Publication Name: Infrastructures

Publication Date: 2025-05-01

Volume: 10

Issue: 5

Page Range: Unknown

Description:

Traffic counts are essential for assessing road capacity to provide efficient, effective, and safe mobility. However, current methods for generating models for traffic count studies are often limited in their accuracy and applicability, which can lead to incorrect or imprecise estimates of traffic volume. This study focused on analyzing and predicting traffic conditions on Ikorodu Road in Lagos State. The analysis involved an examination of historical traffic data, specifically focusing on daily and hourly traffic volumes. The prediction involved the use of machine learning models, including decision trees, gradient boosting, and random forest classifiers. The results of this study revealed significant variations in traffic volume across different days of the week and times of the day, indicating peak and off-peak periods. The study also highlighted the need for a more comprehensive approach that includes additional factors, such as weather conditions, road work, and special events, which could significantly impact traffic volume.

Open Access: Yes

DOI: 10.3390/infrastructures10050122

Script-Based Material and Geometrical Modeling of Steel–Concrete Composite Connections for Comprehensive Analysis Under Varied Configurations

J. Szép M. Movahedi Rad Daniel Gosztola Péter Grubits

Publication Name: Applied Sciences Switzerland

Publication Date: 2025-03-01

Volume: 15

Issue: 6

Page Range: Unknown

Description:

The behavior of steel–concrete composite structures is significantly influenced by the efficiency of the shear connections that link the two materials. This research examines the performance of stud shear connectors, with an emphasis on analyzing the effect of different geometric design parameters. A computational model was created utilizing Python 3.13 to enable thorough digital monitoring of the influence of these parameters on the structural performance of composite connections. Developed within the ABAQUS framework, the model integrates geometric nonlinearity and the Concrete Damage Plasticity (CDP) approach to achieve detailed simulation of structural behavior. Essential design aspects, including stud diameter, stud height, head dimensions, and spacing in both longitudinal and transverse directions, were analyzed. The Python-based parametric model allows for easy modification of design parameters, ensuring efficiency and minimizing modeling errors. The significance of stud diameter changes was analyzed in accordance with Eurocode standards and previous studies. It was found that stud length has a reduced effect on structural performance, particularly when considering the concrete properties used in bridge construction, where compressive failure of the concrete zone is more critical at lower concrete strengths. Additional factors, such as stud head dimensions, were investigated but were found to have minimal effect on the behavior of steel–concrete composite connections. Longitudinal stud spacing emerged as a critical factor influencing structural performance, with optimal results achieved at a spacing of 13d. Spacings of 2d, 3d, and 4d demonstrated overlapping effects, leading to significant performance reductions, as indicated by comparisons of ultimate load and force–displacement responses. For transverse spacing, closer stud arrangements proved effective in reducing the likelihood of slip at the steel–concrete interface, enhancing composite action, and lowering stress concentrations. Additionally, reducing the transverse distance between studs allowed for the use of more shear connectors, increasing redundancy and enhancing performance, especially with grouped-stud connectors (GSCs).

Open Access: Yes

DOI: 10.3390/app15063095

Urban Sustainability Through Pavement Technologies: Reducing Urban Heat Islands with Cool Pavements

Fereidoon Moghadas Nejad Rashid Tanzadeh M. Movahedi Rad Jafar Chalabii Mohammad Javad Amani Mohammad Mohsen Kabiri Nasrabad

Publication Name: Buildings

Publication Date: 2025-02-01

Volume: 15

Issue: 3

Page Range: Unknown

Description:

Urban development driven by population growth and technological advancements has intensified urban heat islands (UHIs), contributing to environmental damage and health risks. This study explores the potential of cool pavements as a critical strategy for mitigating UHIs, focusing on reflective, evaporative, and energy-storing technologies. Over 400 reputable scientific articles were reviewed to analyze UHI causes; measurement methods, including remote sensing and laboratory techniques; and the effectiveness of various pavement solutions. Reflective pavements demonstrated a capacity to lower surface temperatures by 5–20 °C depending on reflectivity changes, while evaporative pavements reduced temperatures by 5–35 °C based on type and design. Advanced energy-storing pavements not only achieved a 3–5 °C temperature reduction but also generated renewable energy. This research provides a comprehensive classification of pavement cooling systems and evaluates their quantitative and qualitative benefits, emphasizing the transformative role of cool pavements in enhancing urban sustainability and reducing UHI effects.

Open Access: Yes

DOI: 10.3390/buildings15030504

Flower Pollination Algorithm on optimal design of space trusses

Edina Koch M. Movahedi Rad Shaymaa Alsamia

Publication Name: International Review of Applied Sciences and Engineering

Publication Date: 2025-10-13

Volume: 16

Issue: 3

Page Range: 418-427

Description:

Abstract: This study assesses the performance of four nature-inspired optimization algorithms—Dynamic Differential Annealed Optimization (DDAO), Flower Pollination Algorithm (FPA), Firefly Algorithm (FF), and Particle Swarm Optimization (PSO) for achieving optimal space truss design. The aim is to minimize the structural weight of three benchmark trusses (10-bar, 25-bar, and 72-bar) while meeting stress and displacement constraints. The key contribution of this work is the first systematic evaluation of FPA in space truss optimization, demonstrating its greater effectiveness in obtaining optimal or near-optimal solutions with faster convergence and higher stability compared to PSO and FF. The results also highlight the limitations of DDAO in handling constrained engineering problems. Findings confirm that FPA and FF are highly effective for structural optimization, offering robust solutions with minimal computational cost. These insights contribute to advancing metaheuristic-based structural design, supporting the adoption of FPA in large-scale optimization problems.

Open Access: Yes

DOI: 10.1556/1848.2025.00958

Optimization of Bolted Steel T-Stub Connection Based on Nonlinear Finite Element Analysis Using Genetic Algorithm

M. Movahedi Rad Péter Grubits Tamás Balogh

Publication Name: Infrastructures

Publication Date: 2025-01-01

Volume: 10

Issue: 1

Page Range: Unknown

Description:

The equivalent T-stub method is frequently employed in infrastructure projects, including bridge engineering, to simplify bolted connection analysis. However, steel connections remain inherently complex due to nonlinear behavior, cost considerations, and code compliance, framing the design process as a discrete structural optimization problem. This research addresses these challenges by presenting a comprehensive calculation framework that combines the finite element method (FEM) and genetic algorithm (GA) to accurately evaluate the structural performance of bolted T-stub configurations. The proposed approach accounts for nonlinear behavior, thereby reflecting realistic structural responses. To enhance the simulation efficiency and reduce the computational time without significantly compromising accuracy, the study introduces a simplified modeling methodology. The effectiveness of the approach is demonstrated through the development and experimental validation of a selected T-stub connection. Furthermore, a parameter sensitivity analysis is conducted to showcase the range of possible outcomes, emphasizing the potential for optimization. Finally, the proposed connections were optimized using GA, highlighting the benefits of structural optimization in achieving efficient and precise designs for steel connections.

Open Access: Yes

DOI: 10.3390/infrastructures10010008

Structural topology optimization for plastic-limit behavior of I-beams, considering various beam-column connections

Marco Domaneschi Peyman Aela M. Movahedi Rad Raffaele Cucuzza Muayad Habashneh Péter Grubits

Publication Name: Mechanics Based Design of Structures and Machines

Publication Date: 2025-01-01

Volume: 53

Issue: 4

Page Range: 2719-2743

Description:

This work proposes topology optimization for steel I-beams, including consideration of bolted beam-column connections with geometric and material nonlinear analysis. The aim is to assess and compare the topological configurations influenced by different connections, examining their stress distribution and rotational stiffness to illustrate the potential of structural optimization. The bi-directional evolutionary structural optimization (BESO) approach is implemented. Furthermore, several bolted steel beam-column configurations were validated based on experimental tests. Subsequently, a series of finite element models were developed, contributing to a comprehensive understanding of the plastic-limit behavior of I-beams under different loading conditions. The proposed method could potentially use a lesser quantity of material while maintaining the same level of structural performance. The results indicate that the implementation of structural topology optimization on I-beams while considering various beam-column connections, yields structural performance similar to that of solid web configurations, achieved through material reduction.

Open Access: Yes

DOI: 10.1080/15397734.2024.2412757

Multi-objective genetic algorithm calibration of colored self-compacting concrete using DEM: an integrated parallel approach

M. Movahedi Rad Vahid Shafaie

Publication Name: Scientific Reports

Publication Date: 2024-12-01

Volume: 14

Issue: 1

Page Range: Unknown

Description:

A detailed numerical simulation of Colored Self-Compacting Concrete (CSCC) was conducted in this research. Emphasis was placed on an innovative calibration methodology tailored for ten unique CSCC mix designs. Through the incorporation of multi-objective optimization, MATLAB's Genetic Algorithm (GA) was seamlessly integrated with PFC3D, a prominent Discrete Element Modeling (DEM) software package. This integration facilitates the exchange of micro-parameter values, where MATLAB’s GA optimizes these parameters, which are then input into PFC3D to simulate the behavior of CSCC mix designs. The calibration process is fully automated through a MATLAB script, complemented by a fish script in PFC, allowing for an efficient and precise calibration mechanism that automatically terminates based on predefined criteria. Central to this approach is the Uniaxial Compressive Strength (UCS) test, which forms the foundation of the calibration process. A distinguishing aspect of this study was the incorporation of pigment effects, reflecting the cohesive behavior of cementitious components, into the micro-parameters influencing the cohesion coefficient within DEM. This innovative approach ensured significant alignment between simulations and observed macro properties, as evidenced by fitness values consistently exceeding 0.94. This investigation not only expanded the understanding of CSCC dynamics but also contributed significantly to the discourse on advanced concrete simulation methodologies, underscoring the importance of multi-objective optimization in such studies.

Open Access: Yes

DOI: 10.1038/s41598-024-54715-4

Probabilistic Topology Optimization Framework for Geometrically Nonlinear Structures Considering Load Position Uncertainty and Imperfections

Oveys Ghodousian Hamed Fathnejat M. Movahedi Rad Muayad Habashneh

Publication Name: Mathematics

Publication Date: 2024-12-01

Volume: 12

Issue: 23

Page Range: Unknown

Description:

In this manuscript, a novel approach to topology optimization is proposed which integrates considerations of uncertain load positions, thereby enhancing the reliability-based design within the context of structural engineering. Extending the conventional framework to encompass imperfect geometrically nonlinear analyses, this research discovers the intricate interplay between nonlinearity and uncertainty, shedding light on their combined effects on probabilistic analysis. A key innovation lies in treating load position as a stochastic variable, augmenting the existing parameters, such as volume fraction, material properties, and geometric imperfections, to capture the full spectrum of variability inherent in real-world conditions. To address these uncertainties, normal distributions are adopted for all relevant parameters, leveraging their computational efficacy, simplicity, and ease of implementation, which are particularly crucial in the context of complex optimization algorithms and extensive analyses. The proposed methodology undergoes rigorous validation against benchmark problems, ensuring its efficacy and reliability. Through a series of structural examples, including U-shaped plates, 3D L-shaped beams, and steel I-beams, the implications of considering imperfect geometrically nonlinear analyses within the framework of reliability-based topology optimization are explored, with a specific focus on the probabilistic aspect of load position uncertainty. The findings highlight the significant influence of probabilistic design methodologies on topology optimization, with the defined constraints serving as crucial conditions that govern the optimal topologies and their corresponding stress distributions.

Open Access: Yes

DOI: 10.3390/math12233686

Reinforcement of RC Two-Way Slabs with CFRP Laminates: Plastic Limit Method for Carbon Emissions and Deformation Control

Oveys Ghodousian Marco Domaneschi Zahraa Saleem Sharhan M. Movahedi Rad Raffaele Cucuzza

Publication Name: Buildings

Publication Date: 2024-12-01

Volume: 14

Issue: 12

Page Range: Unknown

Description:

Carbon-fiber-reinforced polymer (CFRP) laminates have gained attention for their potential to reduce carbon emissions in construction. The impact of carbon-fiber-reinforced polymer (CFRP Laminate) on carbon emissions and the influence of elasto-plastic analysis on this technique were studied in this research. This study focuses on how CFRP can affect the environmental footprint of reinforced concrete structures and how elasto-plastic analysis contributes to optimizing this strengthening method. Four flat RC slabs were created to evaluate this technique in strengthening. One slab was used as a reference without strengthening, while the other three were externally strengthened with CFRP. The slabs, which were identical in terms of their overall (length, width, and thickness) as well as their flexural steel reinforcement, were subjected to concentrated patch load until they failed. The strength of two-way RC slabs was analyzed using a concrete plastic damage constitutive model (CDP). Additionally, CFRP strips were applied to the tension surface of existing RC slabs to improve their strength. The load–deflection curves obtained from the simulations closely match the experimental data, demonstrating the validity and accuracy of the model. Strengthening concrete slabs with CFRP sheets reduced central deflection by 17.68% and crack width by 40%, while increasing the cracking load by 97.73% and the ultimate load capacity by 134.02%. However, it also led to a 15.47% increase in CO2 emissions. Also, the numerical results show that increasing the strengthening ratio significantly impacts shear strength and damage percentage.

Open Access: Yes

DOI: 10.3390/buildings14123873

Sustainable and cost-effective optimal design of steel structures by minimizing cutting trim losses

Marco Domaneschi M. Movahedi Rad Raffaele Cucuzza Giuseppe Carlo Marano

Publication Name: Automation in Construction

Publication Date: 2024-11-01

Volume: 167

Issue: Unknown

Page Range: Unknown

Description:

Since the beginning of the structural optimization field, the optimal design was characterized by the least-weight configuration. In this sense, all the researchers agreed on adopting the minimum-weight optimization statement as the most promising approach to achieve an optimized employment of material. However, especially for steel structures, this approach completely fails the primary goal of encouraging standardization of pieces during the production phase. Except for rare cases, increasing diversity among structural elements leads to a dramatic increase in the financial cost as well as the environmental impact of the structure because of the material waste generated during the cutting procedure. In this paper, a real-coded Genetic Algorithm has been adopted and the well-known one-dimensional Bin Packing Problem has been implemented within the structural optimization process. The Objective Function formulation lies in a marked change of the paradigm in which the target function is represented by the amount of steel required by the factory instead of the structural cost (e.g. weight). The proposed approach is tested on different steel structures moving from 2D truss beams to 3D domes. Addressing the optimal stock of existing elements leads to a significant waste reduction of 40% in almost all the investigated case studies.

Open Access: Yes

DOI: 10.1016/j.autcon.2024.105724

Reliability-based topology optimization of imperfect structures considering uncertainty of load position

Peyman Aela M. Movahedi Rad Raffaele Cucuzza Muayad Habashneh

Publication Name: Structures

Publication Date: 2024-11-01

Volume: 69

Issue: Unknown

Page Range: Unknown

Description:

In this paper, a novel optimization technique is implemented to explore the effects of considering uncertain load positions. Therefore, the integration of reliability-based design into structural topology optimization, while considering imperfect geometrically nonlinear analysis, is proposed. By comparing the results obtained from perfect and imperfect geometrically and materially nonlinear analyses, this study examines the impact of nonlinearity on probabilistic and deterministic analyses. Concerning probabilistic analysis, the originality of this research lies in its incorporation of the position of the applied load as a stochastic variable. This distinctive approach complements the consideration of other relevant parameters, including volume fraction, material properties, and geometrical imperfections, with the overarching goal of capturing the variability arising from real-world conditions. For the assessment of uncertainties, normal distribution is assumed for all these parameters. Normal distributions are chosen due to their advantages in terms of simplicity, ease of implementation, and computational efficiency. These characteristics are particularly beneficial when dealing with complex optimization algorithms and extensive analyses, as is the case in our research. The proposed algorithm is validated according to the results of benchmark problems. Structural examples like cantilever beam, pinned-shell, and L-shaped beam problems are further explored within the context of imperfect geometrically nonlinear reliability-based topology optimization, with specific regard to the probabilistic aspect of the location of the externally applied loads. Moreover, the results of the suggested approach suggest that the inclusion of a probabilistic design strategy has influenced topology optimization. The reliability index acts as a controlling constraint for the resulting optimized configurations, including the mean stress values associated with the resulting topologies.

Open Access: Yes

DOI: 10.1016/j.istruc.2024.107533

Shear Bond Strength in Stone-Clad Façades: Effect of Polypropylene Fibers, Curing, and Mechanical Anchorage

Amin Ghodousian Hossein Mehdikhani Oveys Ghodousian M. Movahedi Rad Vahid Shafaie Mohammad Gorji

Publication Name: Polymers

Publication Date: 2024-11-01

Volume: 16

Issue: 21

Page Range: Unknown

Description:

This study investigates the shear bond strength between four widely used façade stones—travertine, granite, marble, and crystalline marble—and concrete substrates, with a particular focus on the role of polypropylene fibers in adhesive mortars. The research evaluates the effects of curing duration, fiber dosage, and mechanical anchorage on bond strength. Results demonstrate that Z-type anchorage provided the highest bond strength, followed by butterfly-type and wire tie systems. Extended curing had a significant impact on bond strength for specimens without anchorage, particularly for travertine. The incorporation of polypropylene fibers at 0.2% volume in adhesive mortar yielded the strongest bond, although lower and higher dosages also positively impacted the bonding. Furthermore, the study introduces a novel fuzzy logic model using the Dombi family of t-norms, which outperformed linear regression in predicting bond strength, achieving an R2 of up to 0.9584. This research emphasizes the importance of optimizing fiber dosage in adhesive mortars. It proposes an advanced predictive model that could enhance the design and safety of stone-clad façades, offering valuable insights for future applications in construction materials.

Open Access: Yes

DOI: 10.3390/polym16212975

Enhancing fire-resistant design of reinforced concrete beams by investigating the influence of reliability-based analysis

J. Szép M. Movahedi Rad Muayad Habashneh

Publication Name: Engineering Reports

Publication Date: 2024-10-01

Volume: 6

Issue: 10

Page Range: Unknown

Description:

A depth investigation into the impact of high temperatures on the load-bearing capacity of reinforced concrete beams in the case of probabilistic design is presented in this paper, employing advanced finite element analysis techniques. This study addresses a critical knowledge gap in the design of fire-resistant concrete structures, with specific emphasis on the function of concrete cover. The research aims to enhance the overall safety and reliability of concrete buildings under high temperature conditions by providing valuable insights into the behavior of reinforced concrete beams under thermal loading. The analysis incorporates reliability-based modeling to account for uncertainties in temperature distribution within the beams. A validated finite element model is employed to simulate the performance of reinforced concrete beams at elevated temperatures. By considering various concrete cover thicknesses and heat distribution scenarios, the influence of these factors on the load-bearing capacity is thoroughly examined. The results underscore the importance of augmenting the concrete cover to enhance the load-carrying capacity of the beams. Furthermore, the study examines the impact of temperature distribution uncertainties, unveiling diverse load capacities associated with different configurations of concrete cover.

Open Access: Yes

DOI: 10.1002/eng2.12879

Constructability-based design approach for steel structures: From truss beams to real-world inspired industrial buildings

Marco Domaneschi Angelo Aloisio M. Movahedi Rad Raffaele Cucuzza

Publication Name: Automation in Construction

Publication Date: 2024-10-01

Volume: 166

Issue: Unknown

Page Range: Unknown

Description:

This paper presents an optimization framework for steel trusses. The authors implemented a penalty-based approach to optimise the size, shape, and topology based on a dynamic grouping strategy to address the constructability challenges. The main contribution of the paper is the use of damped exponential constructability penalties. This approach ensures optimal designs by balancing structural complexity, through standardization in design, and minimizing the total number of members and variety of sections, with the overall structural cost. The paper also presents a detailed analysis that underscores the sensitivity of the optimization convergence to the algorithmic hyperparameters, emphasizing the role of cross-section assignments and stabilization of truss piece counts. The optimization framework is validated on a trussed roof structure based on the findings from the single truss optimization. The best truss topology proved to be the Howe truss configuration, highlighting its efficiency in meeting the defined objective function.

Open Access: Yes

DOI: 10.1016/j.autcon.2024.105630

Plastic Limited Numerical Modelling on Contact Friction Effects of Steel–Concrete Connection for Composite Bridges

Oveys Ghodousian J. Szép Marco Domaneschi M. Movahedi Rad Raffaele Cucuzza Daniel Gosztola

Publication Name: Buildings

Publication Date: 2024-09-01

Volume: 14

Issue: 9

Page Range: Unknown

Description:

This research employs plastic limit analysis to examine load combinations, contact interactions, and friction effects on steel–concrete connections. A nonlinear finite element model was developed using ABAQUS 2021, incorporating the concrete damage plasticity model and contact friction interactions. The model’s validity was confirmed through laboratory experiments. Results indicate that contact elements and friction between the top flange, concrete slab, and studs significantly influence structural behavior. Unlike conventional push-out tests, real deck–slab connections exhibit different load-displacement responses due to the self-weight and additional loads, such as vehicular traffic. Under horizontal loading, extensive failures with large deformations along the studs occur, while vertically compressive loads lead to failures around the connections.

Open Access: Yes

DOI: 10.3390/buildings14092898

Assessment of soil erosion through spatial analyzing of soil properties using statistical-based functions

Narges Kariminejad M. Movahedi Rad Vahid Shafaie

Publication Name: Bio Web of Conferences

Publication Date: 2024-08-23

Volume: 125

Issue: Unknown

Page Range: Unknown

Description:

The significant geomorphological hazard of collapsed cavities (CC) causes notable environmental transformations. To address this issue, the pipe collapse pattern was examined using two statistical methods, the Density Correlation Function (DCF) and the Mark Coloration Function (MCF). Key predictor variables like organic carbon (OC), sodium adsorption ratio (SAR), and exchangeable sodium percentage (ESP) were utilized to comprehend their impact on spatial distribution over time. The study was found that lower OC levels increase susceptibility to CC, while higher SAR and ESP amounts enhance the potential for collapsed cavities. The methodology and discoveries of this research can offer valuable insights for land managers, stakeholders, and researchers.

Open Access: Yes

DOI: 10.1051/bioconf/202412501008

Analysis of early warning signal of land degradation risk based on time series of remote sensing data

Mohsen Hosseinalizadeh Hamid Reza Pourghasemi Narges Kariminejad Abdolhossein Boali M. Movahedi Rad Vahid Shafaie

Publication Name: Bio Web of Conferences

Publication Date: 2024-08-23

Volume: 125

Issue: Unknown

Page Range: Unknown

Description:

This study explores the spatio-temporal dynamics of the Normalized Difference Vegetation Index (NDVI) to detect early signs of land degradation. Utilizing high-resolution NDVI data from the Google Earth Engine, spanning from 2004 to 2023 with a 30-meter resolution, this research analyzes monthly variations. To illustrate these dynamics, the study focuses on Sabzevar County, located in northeastern Iran, which extends over 7,217 km2and is approximately 220 kilometers distant from Mashhad. Validation of the NDVI data was performed using field observations from strategically located vegetation plots. One square meter plots were systematically established along 100-meter transects (10 transects in total), where the vegetation coverage in each plot was quantitatively assessed by experts. Comprehensive statistical analysis incorporated Kendall's tie test, alongside measurements of autocorrelation, coefficient of variation, and standard deviation, using R software to assess the trends and intensities of NDVI changes. The findings revealed a critical breakpoint in 2020, with increases in all three statistical indices—autocorrelation 0.82, coefficient of variation 0.65, and standard deviation 0.58—indicative of accelerating degradation prior to this year. Furthermore, the intensity of NDVI changes varied significantly across the study area, ranging from 0.05 in central and northern regions to 0.76 in the western parts. This research underscores the value of integrating field data with remote sensing technology to provide a robust analytical tool for early detection of land degradation. This method enables precise, timely assessment and proactive management of vulnerable ecosystems, particularly in arid regions.

Open Access: Yes

DOI: 10.1051/bioconf/202412501011

Effect of the Particle Size Distribution of the Ballast on the Lateral Resistance of Continuously Welded Rail Tracks

Szabolcs Fischer Morteza Esmaeili M. Movahedi Rad Jafar Chalabii Daniel Gosztola

Publication Name: Infrastructures

Publication Date: 2024-08-01

Volume: 9

Issue: 8

Page Range: Unknown

Description:

While the effect of ballast degradation on lateral resistance is noteworthy, limited research has delved into the specific aspect of ballast breakage in this context. This study is dedicated to assessing the influence of breakage on sleeper lateral resistance. For simplicity, it is assumed that ballast breakage has already occurred. Accordingly, nine granularity variations finer than No. 24 were chosen for simulation, with No. 24 as the assumed initial particle size distribution. Initially, a DEM model was validated for this purpose using experimental outcomes. Subsequently, employing this model, the lateral resistance of different particle size distributions was examined for a 3.5 mm displacement. The track was replaced by a reinforced concrete sleeper in the models, and no rails or rail fasteners were considered. The sleeper had a simplified model with clumps, the type of which was the so-called B70 and was applied in Western Europe. The sleeper was taken into consideration as a rigid body. The crushed stone ballast was considered as spherical grains with the addition that they were divided into fractions (sieves) in weight proportions (based on the particle distribution curve) and randomly generated in the 3D model. The complete 3D model was a 4.84 × 0.6 × 0.57 m trapezoidal prism with the sleeper at the longitudinal axis centered and at the top of the model. Compaction was performed with gravity and slope walls, with the latter being deleted before running the simulation. During the simulation, the sleeper was moved horizontally parallel to its longitudinal axis and laterally up to 3.5 mm in static load in the compacted ballast. The study successfully established a relationship between lateral resistance and ballast breakage. The current study’s findings indicate that lateral resistance decreases as ballast breakage increases. Moreover, it was observed that the rate of lateral resistance decrease becomes zero when the ballast breakage index reaches 0.6.

Open Access: Yes

DOI: 10.3390/infrastructures9080129

Strategic assessment of groundwater potential zones: a hybrid geospatial approach

Hamid Nazaripour M. Movahedi Rad Vahid Shafaie Mahdi Sedaghat

Publication Name: Applied Water Science

Publication Date: 2024-08-01

Volume: 14

Issue: 8

Page Range: Unknown

Description:

Groundwater aquifers constitute the primary water supply for populations in arid regions, exemplified by the Goharkooh Plain in Iran's driest drainage basin, where conditions of high evapotranspiration and low precipitation prevail. With the escalating demand for water resources, driven mainly by agricultural expansion, the strategic management of groundwater assets has become increasingly critical. This study focuses on delineating groundwater potential zones (GWPZs) through an integrated approach combining multi-criteria decision analysis and geospatial tools. Based on an extensive literature review, nine thematic layers were selected and developed: lithology, geology, drainage density, slope gradient, elevation, vegetation cover, lineament density, land use, and precipitation. These criteria were initially weighted using the analytical hierarchical process (AHP) and subsequently integrated via weighted overlay analysis. In this research, the strategic selection of thematic layers for assessing groundwater potential in arid regions has been identified as an innovative approach that could significantly advance studies in similar settings. The analysis revealed that approximately 60% of the study area, primarily in the southwestern parts, exhibited moderate to very high groundwater potential. This potential is primarily attributed to the presence of alluvial deposits, low drainage density, and favorable slope and elevation conditions. Applying the receiver operating characteristic (ROC) curve yields an area under the curve (AUC) of 81.5%, indicating a relatively high level of predictive accuracy. These findings demonstrate the efficacy of this integrated approach, suggesting its broader applicability in regions with analogous groundwater challenges and management needs.

Open Access: Yes

DOI: 10.1007/s13201-024-02243-x

Aerodynamic Behavior of Hump Slab Track in Desert Railways: A Case Study in Shuregaz, Iran

Fereidoon Moghadas Nejad Masoud Fathali M. Movahedi Rad Jafar Chalabii Mohammad Mohsen Kabiri Nasrabad

Publication Name: Buildings

Publication Date: 2024-08-01

Volume: 14

Issue: 8

Page Range: Unknown

Description:

The development of rail transport necessitates expanding environmentally friendly infrastructure. However, specific challenges arise in desert and sandy regions. One innovative solution to manage the effects of windblown sand on desert railways is the use of hump slab track superstructure. This paper develops a solid–fluid aerodynamic model based on ANSYS Fluent 2021 R2 software to simulate the hump slab track during a sandstorm. The model is validated through wind tunnel testing. A case study of a railway sandstorm in the Shuregaz region of Iran is presented, evaluating various sandstorm parameters and hump heights to determine their impact on sand concentration and particle velocity within the sand transit channels. The results indicate that increasing the sand particle diameter (from 150 to 250 µm) leads to higher sand concentration (up to 40%) and lower sand movement velocity (up to 28%). These results have been observed with a higher incremental approach concerning the sand flow rate. Conversely, increasing sandstorm velocity (from 10 to 30 m/s) decreases sand concentration and increases sand movement velocity up to 80% and 150%, respectively. Additionally, a 25 cm hump height significantly enhances sand passage by creating larger channels.

Open Access: Yes

DOI: 10.3390/buildings14082473

Numerical Study of the Ultimate Bearing Capacity of Two Adjacent Rough Strip Footings on Granular Soil: Effects of Rotational and Horizontal Constraints of Footings

Mojtaba Lezgy-Nazargah M. Movahedi Rad Vahid Shafaie Mahdi Salari

Publication Name: Buildings

Publication Date: 2024-06-01

Volume: 14

Issue: 6

Page Range: Unknown

Description:

In this paper, the numerical study of the ultimate bearing capacity (UBC) of two closely spaced strip footings on granular soil is investigated using the finite element method (FEM) and upper bound limit analysis (UBLA). Although the UBC of two adjacent footings has previously been studied in other experimental and numerical research, in all the previously reported studies, the footings were not allowed to rotate and move horizontally freely. Due to the deformation of the soil medium, two closely spaced footings are subjected to horizontal movements and tilting, even under central vertical loads. When the two adjacent footings are not permitted to rotate and move in the horizontal directions, the unwanted bending moment and horizontal force act on the footings. Indeed, the UBC of two closely spaced rough footings is evaluated under incorrect constraints in earlier research. In the present research, the UBC of two adjacent rough footings is evaluated with and without these incorrect constraints. The key finding of this study is that constraining the horizontal and rotational movement of the foundation artificially increases the UBC, which does not reflect field conditions. When foundations are permitted to rotate and move horizontally, there is no increase in UBC; however, there is an increased risk of differential settlement and structural instability.

Open Access: Yes

DOI: 10.3390/buildings14061653

Laboratory and Numerical Investigation of Pre-Tensioned Reinforced Concrete Railway Sleepers Combined with Plastic Fiber Reinforcement

Szabolcs Fischer Mykola Sysyn Zoltán Major Sarah Khaleel Ibrahim Dmytro Kurhan Vivien Jóvér Szabolcs Szalai Hanna Csótár Klaudia Madarász András Pollák Dániel Harrach Bálint Molnár L. Gaspar Bence Hermán Szabolcs Kocsis Szurke Attila Németh I. Fekete Richárd Nagy Gusztáv Baranyai Miklós Kuczmann M. Movahedi Rad

Publication Name: Polymers

Publication Date: 2024-06-01

Volume: 16

Issue: 11

Page Range: Unknown

Description:

This research investigates the application of plastic fiber reinforcement in pre-tensioned reinforced concrete railway sleepers, conducting an in-depth examination in both experimental and computational aspects. Utilizing 3-point bending tests and the GOM ARAMIS system for Digital Image Correlation, this study meticulously evaluates the structural responses and crack development in conventional and plastic fiber-reinforced sleepers under varying bending moments. Complementing these tests, the investigation employs ABAQUS’ advanced finite element modeling to enhance the analysis, ensuring precise calibration and validation of the numerical models. This dual approach comprehensively explains the mechanical behavior differences and stresses within the examined structures. The incorporation of plastic fibers not only demonstrates a significant improvement in mechanical strength and crack resistance but paves the way for advancements in railway sleeper technology. By shedding light on the enhanced durability and performance of reinforced concrete structures, this study makes a significant contribution to civil engineering materials science, highlighting the potential for innovative material applications in the construction industry.

Open Access: Yes

DOI: 10.3390/polym16111498

Integrating push-out test validation and fuzzy logic for bond strength study of fiber-reinforced self-compacting concrete

Amin Ghodousian Oveys Ghodousian M. Movahedi Rad Raffaele Cucuzza Vahid Shafaie

Publication Name: Construction and Building Materials

Publication Date: 2024-04-26

Volume: 425

Issue: Unknown

Page Range: Unknown

Description:

This study offers a comprehensive analysis of Fiber-Reinforced Self-Compacting Concrete (FRSCC) with a focus on shear bond strength influenced by specific compositions of microsilica, zeolite, slag, and polypropylene fibers. Twenty distinct FRSCC mixes underwent extensive testing, including 28-day compressive strength, tensile strength assessments, and push-out and slant shear tests. A significant outcome is the strong correlation between the push-out and slant shear test results, exemplified by an R² value of 0.88, confirming the push-out test as a viable and practical alternative for bond strength assessment. Experimentally, fibers were found to enhance tensile strength, with the inclusion of 15% microsilica and slag further amplifying this effect, highlighting the critical role of precise pozzolan selection in achieving optimal mechanical performance and workability in FRSCC. Furthermore, the study introduces a fuzzy logic system for predicting shear bond strength, achieving high predictive accuracy with R² values reaching up to 0.96, depending on the t-norms utilized. This research not only validates the push-out test as a reliable method for evaluating shear bond strength in FRSCC but also demonstrates the efficacy of the fuzzy logic approach, representing a groundbreaking contribution in both computational analysis and practical methodology for concrete structural integrity.

Open Access: Yes

DOI: 10.1016/j.conbuildmat.2024.136062

Plastic-limit probabilistic structural topology optimization of steel beams

M. Movahedi Rad Muayad Habashneh

Publication Name: Applied Mathematical Modelling

Publication Date: 2024-04-01

Volume: 128

Issue: Unknown

Page Range: 347-369

Description:

This work presents a novel geometrically nonlinear analysis with imperfections reliability-based topology optimization (RBTO) approach, considering the volume fraction and geometric imperfections as random variables due to their crucial connections to the manufacturability of web openings in steel I-beams. The objective is achieved by controlling the plastic behavior through limit analysis, which imposes a limit on the plastic ultimate load multipliers. The suggested method is developed by imposing constraints related to the available material volume. The bi-directional evolutionary structural optimization (BESO) method is utilized to fulfill the objectives of this paper. The adequacy of the proposed technique is demonstrated by comparing the results of the algorithm with benchmark steel beams that have conventional web openings. Based on the numerical examples, it appears that the selected technique has the potential to increase the load capacity of steel beams while utilizing the same quantity of material within the design domain. Moreover, the improved beams also exhibit better performance in terms of stress levels. The results of this research suggest that the proposed technique enhances the load capacity of steel beams while maintaining the same quantity of material and improving their performance in terms of stress levels.

Open Access: Yes

DOI: 10.1016/j.apm.2024.01.029

Innovative Design Techniques for Sinusoidal-Web Beams: A Reliability-Based Optimization Approach

J. Szép M. Movahedi Rad Muayad Habashneh Imre Cserpes

Publication Name: Buildings

Publication Date: 2024-04-01

Volume: 14

Issue: 4

Page Range: Unknown

Description:

Existing studies often rely on deterministic numerical analyses for structural models. However, test results consistently highlight uncertainties, particularly in variables such as magnitude of the applied load, geometrical dimensions, material randomness, and limited experiential data. As a response, researchers have increasingly turned their attention to probabilistic design models, recognizing their crucial role in accurately predicting structural performance. This study aims to integrate reliability-based analysis into the numerical modeling of sinusoidal-web steel beams. Two sinusoidal-web beams are considered. The web and the flange thicknesses, in addition to the magnitude of the applied load, are treated as random variables with mean values and standard deviations. Notably, the study demonstrates the efficiency of the reliability index as a governing limit in the analysis process. A detailed comparison between deterministic and probabilistic designs of sinusoidal-web beams is conducted, focusing on the impact of introducing the nature of randomness. Therefore, this study’s results deepen our understanding of how uncertainties significantly influence deformations and stresses.

Open Access: Yes

DOI: 10.3390/buildings14041051

Advanced elasto-plastic topology optimization of steel beams under elevated temperatures

Marco Domaneschi M. Movahedi Rad Raffaele Cucuzza Muayad Habashneh

Publication Name: Advances in Engineering Software

Publication Date: 2024-04-01

Volume: 190

Issue: Unknown

Page Range: Unknown

Description:

A topology optimization algorithm of steel beams under the influence of elevated temperature, considering the geometrically nonlinear analysis of imperfect structures, is proposed in this work. The proposed methodology is developed for addressing topology optimization problems in the presence of initial geometric imperfections and thermoelastic-plastic analysis by developing the bi-directional evolutionary structural optimization (BESO) method. Two comprehensive examples of lipped channel beams and steel I-section beams are provided to demonstrate the effectiveness of the proposed approach. The considered examples explore the impact of elevated temperature on the topology optimization of imperfect steel beams, considering the interplay between thermal effects, structural imperfections, and nonlinear behavior. The results highlight the significance of integrating temperature effects in achieving optimal and robust steel beam designs. Furthermore, the openings generated by the proposed algorithm can efficiently disrupt the continuous heat flow within the material, leading to regions with reduced thermal conductivity compared to solid regions.

Open Access: Yes

DOI: 10.1016/j.advengsoft.2024.103596

Numerical Covariance Evaluation for Linear Structures Subject to Non-Stationary Random Inputs

Marco Domaneschi L. Sardone M. Movahedi Rad Raffaele Cucuzza Giuseppe Carlo Marano Santiago Londoño López

Publication Name: Computation

Publication Date: 2024-03-01

Volume: 12

Issue: 3

Page Range: Unknown

Description:

Random vibration analysis is a mathematical tool that offers great advantages in predicting the mechanical response of structural systems subjected to external dynamic loads whose nature is intrinsically stochastic, as in cases of sea waves, wind pressure, and vibrations due to road asperity. Using random vibration analysis is possible, when the input is properly modeled as a stochastic process, to derive pieces of information about the structural response with a high quality (if compared with other tools), especially in terms of reliability prevision. Moreover, the random vibration approach is quite complex in cases of non-linearity cases, as well as for non-stationary inputs, as in cases of seismic events. For non-stationary inputs, the assessment of second-order spectral moments requires resolving the Lyapunov matrix differential equation. In this research, a numerical procedure is proposed, providing an expression of response in the state-space that, to our best knowledge, has not yet been presented in the literature, by using a formal justification in accordance with earthquake input modeled as a modulated white noise with evolutive parameters. The computational efforts are reduced by considering the symmetry feature of the covariance matrix. The adopted approach is applied to analyze a multi-story building, aiming to determine the reliability related to the maximum inter-story displacement surpassing a specified acceptable threshold. The building is presumed to experience seismic input characterized by a non-stationary process in both amplitude and frequency, utilizing a general Kanai–Tajimi earthquake input stationary model. The adopted case study is modeled in the form of a multi-degree-of-freedom plane shear frame system.

Open Access: Yes

DOI: 10.3390/computation12030050

Assessing Future Hydrological Variability in a Semi-Arid Mediterranean Basin: Soil and Water Assessment Tool Model Projections under Shared Socioeconomic Pathways Climate Scenarios

Aliakbar Nazari Samani Arash Zare Garizi M. Movahedi Rad Vahid Shafaie Marziyeh Haji Mohammadi

Publication Name: Water Switzerland

Publication Date: 2024-03-01

Volume: 16

Issue: 6

Page Range: Unknown

Description:

Climate is one of the main drivers of hydrological processes, and climate change has caused worldwide effects such as water scarcity, frequent floods and intense droughts. The purpose of this study was to analyze the effects of climate change on the water balance components, high flow and low flow stream conditions in a semi-arid basin in Iran. For this reason, the climate outputs of the CanESM5 model under Shared Socioeconomic Pathways (SSP) scenarios SSP126, SSP245, and SSP585 were spatially downscaled by the Statistical Downscaling Model (SDSM). The hydrological process was simulated by the Soil and Water Assessment Tool (SWAT) model. Key findings include a 74% increase in evapotranspiration, a reduction by up to 9.6% in surface runoff, and variations in discharge by up to 53.6%. The temporal analysis of snow melting changes revealed an increase in the volume of snow melting during winter months and a reduction in the volume during spring. The projected climate change is expected to cause notable variations in high and low flow events, particularly under the SSP585 scenario, which anticipates significant peaks in flow rates. This comprehensive analysis underscores the pressing need for adaptive strategies in water resource management to mitigate the anticipated impacts of climate variability.

Open Access: Yes

DOI: 10.3390/w16060805

Optimizing structural topology design through consideration of fatigue crack propagation

M. Movahedi Rad Muayad Habashneh

Publication Name: Computer Methods in Applied Mechanics and Engineering

Publication Date: 2024-02-01

Volume: 419

Issue: Unknown

Page Range: Unknown

Description:

This paper presents an advanced approach for structural topology optimization by incorporating fatigue crack propagation analysis. The extended finite element method (X-FEM) is employed to model initial crack propagation, while the Paris model serves as the basis for simulating fatigue crack growth. The proposed methodology aims to optimize the structural design by minimizing compliance while considering volume and fatigue constraints. The proposed method employs the developed bi-directional evolutionary structural optimization (BESO) algorithm. The accuracy of the proposed technique is validated through the solution of benchmark problem and is further demonstrated in its effectiveness and robustness by examining several numerical examples. The optimization process considers various crack conditions, including the absence of cracks, horizontal and vertical cracks of different lengths. The optimized topologies obtained through the proposed algorithm clearly demonstrate the impact of crack presence, crack direction, and crack length on the material distribution. Furthermore, the convergence histories of the objective function, represented by mean compliance, highlight the influence of crack length on the stiffness and converged compliance of the structure. The results demonstrate its ability to adapt the material distribution based on fatigue cracks propagation conditions and achieve optimal topologies that balance structural integrity and performance.

Open Access: Yes

DOI: 10.1016/j.cma.2023.116629

Investigation of Shear Strength Reduction Method in Slope Stability of Reinforced Slopes by Anchor and Nail

Seyed Mohammad Reza Imam Farshad Astaraki M. Movahedi Rad Jafar Chalabii Seyedsaber Hosseini

Publication Name: Buildings

Publication Date: 2024-02-01

Volume: 14

Issue: 2

Page Range: Unknown

Description:

Since the stability of slopes in infrastructures such as road and railroad embankments, excavations, and, in general, earthwork is important, analyzing the stability of these slopes has been one of the main focuses of geotechnical engineers. Although analyzing both reinforced and unreinforced slopes is needed, reinforced slopes require special attention as the reinforcement elements significantly affect the calculations. Hence, the current study’s aim is to find out the differences between obtained safety factors using the Limit Equilibrium Method (LEM) and Shear Strength Reduction Method (SSRM). For this purpose, first, the origin differences in terms of Safety Factor (SF) are theoretically determined according to basic formulas for the aforementioned techniques. Then, to verify the formula, several numerical modelings are carried out using in situ measured geotechnical data to better understand the differences in terms of safety factors. The results indicate that for the reinforced slope with an SF value of higher than 1, the SSRM provides a higher SF in comparison with the other techniques, and the origin of this difference is the definitions of the SF in the different methods.

Open Access: Yes

DOI: 10.3390/buildings14020432

Probabilistic Topology Optimization of Steel I-Beam Web Configurations Under Varied Load Positions

M. Movahedi Rad Muayad Habashneh

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 30-36

Description:

This study investigates the impact of uncertain load positions through an innovative optimization technique. It seamlessly integrates reliability-based design into the optimization of the structural topology, with a specific focus on the web portion of steel I-beams and including geometrical imperfection analysis. The study operates under the premise that the applied load is randomly positioned, engaging in a comprehensive probabilistic analysis. This methodology extends its considerations to additional factors, such as material properties, volume fraction, and geometric imperfections. The assumption of a normal distribution for each of these parameters aids in quantifying uncertainties. Moreover, the proposed work leverages the notion of plastic ultimate load multipliers to illustrate how the algorithm can improve the performance of steel beams. To evaluate the algorithm, the results of a benchmark problem were meticulously analyzed. While exploring the probabilistic nature of externally applied force positions, a numerical example was conducted involving a steel I-beam within the context of reliability-based imperfect geometry topology optimization. The outcomes of the proposed method underscore that the integration of probabilistic design significantly influences the topology optimization process.

Open Access: Yes

DOI: 10.3233/ATDE240523

Analytical Study of Steel-Polypropylene Hybrid Fibre-Reinforced Concrete Deep Beams with Different Shear Span-to-Depth Ratios

M. Movahedi Rad Sarah Khaleel Ibrahim

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 406-414

Description:

This study explores the performance of steel-polypropylene hybrid fibrereinforced concrete deep beams across various shear span-to-depth ratio values. Combining the ductility of steel fibres with the crack control properties of polypropylene fibres, the research includes experimental work and numerical calibration using ABAQUS. Various parameters, including load locations and shear span-to-depth ratios (0.5 < a/d < 1.5), are considered alongside different steelpolypropylene fibre ratios. The results indicate that reducing the shear span-to-depth ratio enhances the shear strength of the deep beams and reduces deflection values. additionally, the steel-polypropylene fibres influence the overall behaviour, affecting the load-deflection behaviour and damage patterns highlighting insights for designing efficient deep beams in practical applications.

Open Access: Yes

DOI: 10.3233/ATDE240573

Advanced Numerical Simulation and Modeling of Multi-Pass Welding Processes: Detailed Analysis of Temperature Distribution in Structural Elements

J. Szép M. Movahedi Rad Daniel Gosztola Péter Grubits

Publication Name: Chemical Engineering Transactions

Publication Date: 2024-01-01

Volume: 114

Issue: Unknown

Page Range: 823-828

Description:

The growing importance of numerical simulations in the welding industry stems from their ability to enhance structural performance and sustainability by ensuring optimal manufacturing conditions. The use of the finite element method (FEM) allows for detailed and precise calculations of the mechanical and material changes caused by the welding process. Acquiring knowledge of these parameters not only serves to augment the quality of the manufacturing process but also yields consequential benefits, such as reducing adverse effects. Consequently, the enhancement of structural performance and prolonged lifespan becomes achievable, aligning with overarching sustainability goals. To achieve this goal, this paper utilizes numerical simulations of welding processes based on experimental tests, with a specific focus on analyzing temperatures generated within the structures. In the finite element analysis (FEA), a total of 12 welding cycles were systematically modeled to align with experimental conditions, incorporating cooling intervals, preheating considerations, and the relevant section of the connecting concrete structure with studs. The outcomes of this research exemplify the potential of numerical simulation in the welding industry, demonstrating a diverse range of results achieved through FEA to enhance the quality of structures within the context of sustainability.

Open Access: Yes

DOI: 10.3303/CET24114138

The Effect of the Friction Coefficient Between the Steel-Concrete Connection on the Horizontal Load Capacity

J. Szép M. Movahedi Rad Daniel Gosztola

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 143-150

Description:

This article presents experimental tests and numerical modeling of steelcomposite connections. The study considers the interaction and friction coefficient between the steel structure and concrete, as well as between the steel studs and concrete. The numerical model underwent validation through an iterative process, considering various friction coefficients. The friction coefficient between the structure and the concrete exerted the most significant impact on the load capacity. a new finite element model has been developed, with various friction coefficients between steel structure and concrete, and in this model, the concrete was also subjected to different vertical compression loads. A total of 25 numerical tests have been conducted, using various configurations of vertical load and friction coefficient parameters. It was observed that higher friction coefficients increase the impact of vertical forces on the horizontal load capacity. The friction coefficient can be increased through technological interventions, such as surface roughening techniques or the introduction of intermediate materials designed to elevate it.

Open Access: Yes

DOI: 10.3233/ATDE240538

Reliability-Based Optimization of Sinusoidal-Web Steel Beams: Integrating Experimental and Numerical Analyses for Enhanced Structural Performance

M. Movahedi Rad Muayad Habashneh Imre Cserpes Gábor Csaba Soóki-Tóth

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 415-421

Description:

A new method for optimizing the design of nonlinear sinusoidal-web steel beams is introduced in this paper, focusing on reliability-based design principles. Utilizing a custom-written code with a reliability index as a key control factor, the study incorporates stochastic variables such as flange thickness, sinus wave width, sinusoidal-web plate thickness, and applied load magnitudes. Employing Finite Element Analysis (FEA) through ABAQUS software conducting experimental testing on sinusoidal HEA beams, this research showcases the successful application of reliability-based design in modifying beam design to meet the reliability requirements. The adoption of the suggested approach, which incorporates Monte Carlo simulation, is crucial in guiding the development of structural configurations that are robust to random nature in both load and manufacturing conditions. Results showcase improved structural integrity, and the successful convergence of optimized values, emphasizing the potential for enhanced steel structure design.

Open Access: Yes

DOI: 10.3233/ATDE240574

DEM Analysis of Ballast Particle Direct Shear Tests: Exploring the Influence of Varying Particle Size Distributions on Shear Stress

M. Movahedi Rad Jafar Chalabii

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 88-95

Description:

The dimension of particles can significantly influence the load response and the performance of uniformly graded ballast layers in railway track structures in real-world conditions. Yet, the micromechanical behavior of the unbound aggregate ballast layer assembly, particularly affected by particle size, remains largely unexplored. In this study, the distinct element model of a direct shear test was initially simulated using friction coefficients of 0.8, 0.9, and 1, and particle size distribution No.4A. The dimensions of the shear test box were 300 mm in width, 300 mm in length, and 180 mm in height. Additionally, a constant normal force of 333 kPa was applied to the sample during the simulation. Subsequently, this model was compared with experimental results, revealing a close correspondence between simulated and experimental shear stress-displacement curves, particularly for the friction coefficient of 1. Following this verification, the validated model was employed to investigate three other particle size distributions: No.4, No.5, and No.57. The results demonstrated a reduction in shear stress for particle size distributions No.4, No.5, and No.57 compared to No.4A, with quantified decreases of 11.9%, 38.2%, and 56.7%, respectively.

Open Access: Yes

DOI: 10.3233/ATDE240531

Numerical Modeling of Multi-Pass Arc Welding Processes: Integration with Experimental Validation for Distortion analysis and Characterization

J. Szép Marco Domaneschi M. Movahedi Rad Raffaele Cucuzza Daniel Gosztola Péter Grubits

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 248-254

Description:

The increasing significance of numerical simulations in the welding industry arises from their capacity to improve manufacturing conditions, ensuring greater effectiveness and precision. The utilization of the finite element method (FEM) enables comprehensive and focused calculations of mechanical and material structural alterations induced by the welding process. Acquiring knowledge of these parameters not only serves to augment the quality of the manufacturing process but also yields consequential benefits, such as reducing adverse effects like base plate distortion. Consequently, enhancing structural performance and prolonging lifespan becomes achievable, aligning with overarching sustainability goals. To accomplish this objective, this paper involves the numerical simulation of a welding process based on experimental tests, with a focus on investigating the deformations caused by the heat generated during welding as the primary parameter of interest. Advanced modeling techniques are employed to assess the results as part of a comprehensive thermo-mechanical analysis framework, examining and characterizing the impact of the temperature distribution. In the finite element analysis (FEA), a total of 12 welding cycles were systematically modeled to align with experimental conditions, incorporating cooling intervals and preheating considerations. The outcomes of this research exemplify the potential of numerical simulation in the welding industry, demonstrating a diverse range of results achieved through FEA to enhance the quality of structures.

Open Access: Yes

DOI: 10.3233/ATDE240552

Discrete Element Modelling Analysis of Particle Breakage Criteria in Direct Shear Tests

M. Movahedi Rad M. Amine Benmebarek Sadok Benmebarek

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 60-66

Description:

Discrete Element Modelling (DEM), employing the replacement method, has been extensively utilized to investigate the micro and macroscopic behavior of soil with particle breakage. Despite numerous breakage criteria proposed in the literature, an agreement on the most appropriate criterion remains unclear. In this study, three-dimensional DEM analyses were conducted using Particle Flow Code (PFC3D) to assess stress distribution and identify potential locations of particle crushing during direct shear tests for coarse sand subjected to different high normal stresses. The investigation focused on employing a breakage criterion featuring Weibull distribution of particle strengths and considers the effect of particle size on average strength to predict the occurrence of fractures. Various breakage criteria, including major principal stress, mean stress, octahedral shear stress within a particle, and stress calculated from the maximum contact force on a particle, were each examined. The findings indicate that potential crushable particles were predominantly situated near diagonal shear band. Notably, results demonstrate that criteria based on octahedral shear stress and maximum contact force prove more effective in accurately reproducing the concentration of crushed particles near the shear band.

Open Access: Yes

DOI: 10.3233/ATDE240527

Stiffness Ratio Evaluation of Steel Exoskeletons Through Performance-Based Optimal Design

Marco Domaneschi M. Movahedi Rad Raffaele Cucuzza Giuseppe Carlo Marano Jana Olivo Giuseppe Andrea Ferro

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 438-445

Description:

Among the various seismic retrofitting techniques, steel exoskeletons are distinguished by their non-invasive nature. However, only a few consolidated methodologies have been proposed for their design. The approach of several standard codes is based on the classification of elements according to their relative stiffness. In this way, a ratio between the stiffness of the exoskeletons and that of the building is taken as the main design parameter. In this study, a performancebased design approach was employed, with the inter-story drift of the building as the performance target. A sensitivity analysis was conducted to assess the impact of different inter-story drift thresholds on the structural behavior of the buildingexoskeleton system. For each threshold, an optimization process was conducted to identify the optimal number of exoskeletons, their placement around the building, and the dimensions of their elements. Finally, the stiffness ratios were determined for each optimal configuration and were compared to the threshold provided by the regulations. This comparison yielded interesting insights into the differences in the approaches.

Open Access: Yes

DOI: 10.3233/ATDE240577

Fuzzy Logic and Push-Out Test Innovations for Fiber-Reinforced Self-compacting Concrete Assessment

Oveys Ghodousian M. Movahedi Rad Vahid Shafaie Géza Herczeg

Publication Name: Fib Symposium

Publication Date: 2024-01-01

Volume: Unknown

Issue: Unknown

Page Range: 855-862

Description:

This research addresses the deterioration of concrete infrastructures, emphasizing the efficacy of Fiber-Reinforced Self-Compacting Concrete (FRSCC) in repair applications. The study investigates the bond strengths between new and existing concrete layers, employing both experimental and numerical methods to evaluate traditional and innovative testing approaches, including slant shear and push-out tests. Results demonstrate that FRSCC, enhanced with polypropylene fibers, significantly improves structural resilience and mechanical properties. The introduction of fuzzy logic models further refines the prediction of bond strengths, offering a robust framework for future concrete technology advancements.

Open Access: Yes

DOI: DOI not available

Model Calibration of High Damping Rubber Bearings: A Preliminary Mass Production Reliability Study

Marco Domaneschi M. Movahedi Rad Raffaele Cucuzza Giuseppe Carlo Marano Santiago Londoño López

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 389-397

Description:

Over the past decade, Building Isolation Systems (BIS) have gain significant relevance due to their ability to reduce horizontal acceleration and interstory drifts in structures. Since the 1950s, researchers have focused on developing numerical models to simulate the dissipative behavior of High Damping Rubber Bearings (HDRB) in parallel major earthquake events have highlighted the need for BIS devices in medium and large-scale infrastructure, accentuating the need for further research into accurate models and adding the pressing interest in variability of mass-produced HDRB parameters. This study presents initial results from an identification process using two numerical models, validated using experimental tests at the SISMALAB laboratory. The experimental data involved eight samples subjected to compression forces and horizontal displacement. Optimal values were obtained through a Genetic Algorithm optimization process, minimizing discrepancies between experimental and numerical response. Preliminary variability analysis was conducted on data from 20 independent iterations over the eight samples.

Open Access: Yes

DOI: 10.3233/ATDE240571

Strengthening RC Slabs with CFRP Bars Using the Plastic Limit Method to Control Plastic Deformation

Marco Domaneschi Zahraa Saleem Sharhan M. Movahedi Rad Raffaele Cucuzza

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 96-104

Description:

The objective of this work is to improve the punching strength and control the plastic deformation of two-way reinforced concrete (RC) slabs using carbon fiber reinforced polymer (CFRP) bars. The efficacy of this reinforcement technique was evaluated by constructing four reinforced concrete flat slabs. One specimen was utilized as a reference slab, while the other three specimens were reinforced using the Near Surface Mounted (NSM) CFRP bars approach. The slabs, which had identical dimensions and steel reinforcement, were exposed to patch load, and tested until they reached the point of failure. For evaluating the strength of two-way reinforced concrete (RC) slabs, the Concrete Plastic Damage (CDP) constitutive model was developed and implemented. CFRP bars are inserted into the slab at a depth from the tension face to enhance their strength. The investigation commences with the calibration of a numerical model utilizing data obtained from laboratory experiments. This will be achieved by establishing an advanced analytical method that incorporates the plasticity of concrete damage and the use of CFRP bars, along with a multiplier to determine the plastic limit load. Numerical simulations are employed to investigate shear dynamics by including diverse elements. The results showed that an increase in the ratio of strengthening had a significant effect on shear strength.

Open Access: Yes

DOI: 10.3233/ATDE240532

Numerical Study of the Geogrid Reinforced Soil Wall Incorporating Strain-Softening Constitutive Soil Model

Seyed Ali Emamian M. Movahedi Rad Vahid Shafaie Géza Herczeg Mahdi Salari

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 327-333

Description:

This study embarks on a numerical exploration of Geogrid Reinforced Soil Walls (GRSW), employing finite difference analysis to compare two soil constitutive models, highlighting the efficacy of a refined strain-softening model. This innovative approach markedly improves the prediction of GRSW performance, particularly aligning the safety factor more closely with real-world observations. Notably, the strain-softening model demonstrates a superior ability over the perfectly plastic model by significantly reducing the mean overall error in predicting maximum geogrid strain overall from 51% to 30%, reflecting a significant 41% improvement in precision, thereby presenting a significant tool for enhancing geotechnical design practices. The research underlines the potential of this model to elevate the safety and reliability of GRSW constructions, contributing to elevated design standards within the field of geotechnical engineering.

Open Access: Yes

DOI: 10.3233/ATDE240563

A Sustainable Approach for Reversing the Structural Design Process of Steel Structures: From the Traditional Minimum-Weight Approach to the Cutting Losses Minimization

Marco Domaneschi Roberta Di Bari M. Movahedi Rad Raffaele Cucuzza Giuseppe Carlo Marano

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 446-454

Description:

In this research, a Genetic Algorithm (GA) has been developed and the well-known one-dimensional bin packing problem (BPP) has been implemented within the structural optimization process. The Objective Function formulation lies in a marked change of the paradigm in which the target function is represented by the amount of steel required by the factory instead of the structural cost (e.g. weight). The best design is obtained by varying the geometry properties of the members and the cross-section assignation ensuring optimal stock of existing elements. Finally, the structural cost and the Carbon emission are calculated for a spatial reticular dome. The mass of the waste with respect to the mass of the stock, Mwaste/Mstock, is evaluated by adopting both the cutting Stock approach and the traditional approach. The former leads to a waste saving that is almost twice that obtained from the latter. However, no significant differences in terms of carbon emission can be observed by comparing the two approaches.

Open Access: Yes

DOI: 10.3233/ATDE240578

Optimum Train Weighing in Motion using Inertial Sensors

Szabolcs Fischer Morad Shadfar M. Movahedi Rad Milad Kazemian Ahmad Mohammadi Doost Ebrahim Hadizadeh Raisi

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2024-01-01

Volume: 21

Issue: 1

Page Range: 221-240

Description:

Continuous monitoring with advanced equipment and innovative scientific techniques is essential for timely and perfect maintenance. The interaction and dynamic force between wheel and rail is one of the most widely monitored issues. In this paper's case study of ballasted railway tracks in Iran, a set consisting of two separate strain gauge arrays and three different positions for installing accelerometers were designed according to the conditions. After installation, the system was calibrated with a predetermined passing axle load. The dependency of the arrays' and the equipment's installation location with the velocity of the passing axle load was examined as part of the field study after repeated investigation and comparisons of the setups' results. In order to gather data with the least error and the highest level of accuracy, it was decided on the more appropriate array with less dependence and a better installation position.

Open Access: Yes

DOI: 10.12700/APH.21.1.2024.1.14

Non-Linear Time History and Pushover analysis of a Steel Silo Behavior

Oveys Ghodousian Farhood Shahidi Farhad Shahidi M. Movahedi Rad Vahid Shafaie

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 334-341

Description:

Earthquakes, among the most destructive natural hazards, result in substantial economic and demographic losses. An effective strategy to mitigate future structural damage involves investigating past collapses. Numerical modeling proves instrumental in analyzing and identifying deficiencies in collapsed structures. This study numerically evaluates a steel silo damaged during the 2011 Van earthquake. Employing non-linear time history and pushover analyses, the research assesses the silo's performance. Findings highlight inadequate welding dimensions and incomplete fusion with the base metal in fillet welds between columns and the silo tank as primary causes of collapse. Numerical simulations with varied column removal scenarios underscore the importance of robust silo tank-column connections in reducing earthquake-induced damage.

Open Access: Yes

DOI: 10.3233/ATDE240564

Reliability‑based probabilistic numerical plastically limited analysis of reinforced concrete haunched beams

M. Movahedi Rad Sarah Khaleel Ibrahim

Publication Name: Scientific Reports

Publication Date: 2023-12-01

Volume: 13

Issue: 1

Page Range: Unknown

Description:

This research proposes a novel method that considers the optimal reliability-based design of reinforced concrete haunched beams subjected to probabilistic concrete properties and complementary strain energy values. The theory is applied twice, once to evaluate a deterministic solution, where the plastic behaviour is constrained by the complementary strain energy of residual stresses induced within steel bars. Secondly, the same method is considered for a probabilistic solution where the concrete characteristics—compressive strength and modulus of elasticity—and complementary strain energy value vary randomly. The reliability index acts as a bound for the solution. It is important to mention that the model utilised in this publication is derived from recent research after being calibrated using Abaqus. This work represents an extension of that recent research that exclusively considered deterministic work. This research led deterministically to new estimates for the complementary strain energy, which will be interpreted as reflecting the behaviour of plastic thresholds and quantifying the associated loads. Afterwards, uncertainty is studied when probability interferes, showing various load values and damage in concrete and steel when the complementary strain energy and concrete properties are probabilistically evaluated, giving a less reliable solution as the load reduces. These effects are reflected in the varying plastic behaviour of the investigated haunched beams.

Open Access: Yes

DOI: 10.1038/s41598-023-29930-0

Elasto-plastic analysis and optimal design of composite integral abutment bridge extended with limited residual plastic deformation

J. Szép M. Movahedi Rad Sarah Khaleel Ibrahim Dániel Harrach Daniel Gosztola Ferenc Papp

Publication Name: Scientific Reports

Publication Date: 2023-12-01

Volume: 13

Issue: 1

Page Range: Unknown

Description:

Due to the growing significance of structural theories concerning the composite structure analysed and designed plastically, this paper introduces a new optimisation method for controlling the plastic behaviour of a full-scale composite integral abutment bridge by employing complementary strain energy of residual forces that existed within the reinforcing rebars. Composite bridges are structures made of components such as steel and concrete, which are frequent and cost-effective building methods. Thus, various objective functions were used in this work when applying optimum elasto-plastic analysing and designing the composite integrated bridge structure that was tested experimentally in the laboratory. In contrast, the plastic deformations were constrained by restricting the complementary strain energy of the residual internal forces aiming to find the maximum applied load and the minimum number of steel bars used to reinforce the concrete column part of the structure. The numerical model employed in this paper was validated and calibrated using experimental results, which were considered inside ABAQUS to produce the validated numerical model, using concrete damage plasticity (CDP) constitutive model and concrete data from laboratory testing to solve the nonlinear programming code provided by the authors. This paper presents a novel optimization method using complementary strain energy to control the plastic behaviour of a full-scale composite integral abutment bridge, with the original contribution being the incorporation of residual forces within reinforcing rebars to limit plastic deformations. Following that, a parametric investigation of the various optimisation problems revealed how models performed variously under different complementary strain energy values, which influenced the general behaviour of the structure as it transitioned from elastic to elasto-plastic to plastic; also results showed how the complementary strain energy value is connected with the amount of damaged accrued in both concrete and steel.

Open Access: Yes

DOI: 10.1038/s41598-023-32787-y

Reliability based bi-directional evolutionary topology optimization of geometric and material nonlinear analysis with imperfections

János Lógó M. Movahedi Rad Muayad Habashneh

Publication Name: Computers and Structures

Publication Date: 2023-10-15

Volume: 287

Issue: Unknown

Page Range: Unknown

Description:

This paper aims to present a novel computational technique for using reliability-based design while taking into account the effect of geometrically and materially nonlinear imperfect analysis. Consequently, a new bi-directional evolutionary structural optimization scheme is developed. A comparison is made between perfect geometrically and materially nonlinear analysis and imperfect geometrically and materially nonlinear analysis topology optimization designs for both deterministic and probabilistic analysis. In the case of probabilistic analysis, relevant parameters such as volume fraction (including manufacturing imprecisions), material properties, and geometrical imperfections (for stability calculations) are assumed to be random variables that follow a normal distribution to represent the uncertainties. The considered numerical examples have successfully illustrated that the proposed method can find the optimal topology for a reliability-based design using perfect geometrically and materially nonlinear analysis and imperfect geometrically and materially nonlinear analysis. Additionally, the results of the topology optimization according to the mean stress and the final optimized shapes have been influenced by introducing a reliability-based design, considering the reliability index as a bound governing the process.

Open Access: Yes

DOI: 10.1016/j.compstruc.2023.107120

Numerical Investigation of the Effect of Longitudinal Fiberglass Dowels on Tunnel Face Support in Layered Soils

Morteza Esmaeili Farshad Astaraki M. Movahedi Rad Jafar Chalabii Jafar Hosseini Manoujan

Publication Name: Infrastructures

Publication Date: 2023-10-01

Volume: 8

Issue: 10

Page Range: Unknown

Description:

Tunnel face extrusion rigidity is an important factor for solving stress–strain problems in loose ground conditions. In previous studies, the effect of horizontal and vertical soil layering on tunnel excavation face stability in the presence of longitudinal fiberglass dowels has not been studied. Therefore, in this study, the effect of fiberglass dowels on the stability of the tunnel face in layered soil has been investigated. In this matter, the best dowel arrangement for minimizing the excavation face extrusion in the case of two-layer soil (horizontal or vertical) has been focused on. For this purpose, firstly, a 3D numerical model was validated based on field data provided previously, and then a 3D numerical tunnel was developed in FLAC3D, adopting the Mohr–Coulomb failure criterion. In continuation, the effect of tunnel diameter, initial pressure ranging from 0.5 to 1.5 MPa, and different placement angles of fiberglass dowels ranging from 0 to 9 degrees, with respect to the tunnel longitudinal axes on the tunnel face extrusion, have been investigated. In the case of horizontal layering, the results showed that the maximum extrusion rate is significantly increased where the elasticity modulus of the soil is reduced. In addition, comparing the maximum extrusion in vertical and horizontal layering, it was found that its value in the horizontal mode is much higher than in the vertical. Additionally, the extrusion of the tunnel face has changed significantly due to an alteration in the initial stress. Finally, it was discovered that tunnel face extrusion is not significantly affected by altering the angle of the fiberglass dowels.

Open Access: Yes

DOI: 10.3390/infrastructures8100138

A developed probabilistic elasto-plastic bi-directional structural optimization framework

M. Movahedi Rad Muayad Habashneh

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2023-09-15

Volume: 39

Issue: Unknown

Page Range: 1-8

Description:

This work introduces a new approach for probabilistic elastoplastic topology optimization based on the improved bidirectional structural optimization (BESO) technique. To consider uncertainties, the volume fraction and the material properties are considered randomly. Thus, the reliability-based design is integrated into the deterministic design by applying a reliability constraint to the optimization problem. Furthermore, using limit analysis, a bound is applied to the plastic limit load multipliers to govern the plastic behavior of the problems. Results from a 2D benchmark problem are used to illustrate how adequate the approach that has been provided is. Also, a 2D elastoplastic numerical example is shown to illustrate the proposed method's capability of identifying the best topology for elastoplastic models in the context of reliability-based design. The results indicate that the reliability constraints work effectively as a bound that reduces the yielding states.

Open Access: Yes

DOI: 10.3233/ATDE230413

Reliability based topology optimization of thermoelastic structures using bi-directional evolutionary structural optimization method

M. Movahedi Rad Muayad Habashneh

Publication Name: International Journal of Mechanics and Materials in Design

Publication Date: 2023-09-01

Volume: 19

Issue: 3

Page Range: 605-620

Description:

The aim of this paper is to propose a novel computational technique of applying reliability-based design to thermoelastic structural topology optimization. Therefore, the optimization of thermoelastic structures' topology based on reliability-based design is considered by utilizing geometrical nonlinearity analysis. For purposes of introducing reliability-based optimization, the volume fraction parameter is viewed as a random variable with a normal distribution having a mean value and standard deviation. The Monte Carlo simulation approach for probabilistic designs is used to calculate the reliability index, which is used as a constraint related to the volume fraction constraint of the deterministic problem. A new bi-directional evolutionary structural optimization scheme is developed, in which a geometrically nonlinear thermoelastic model is applied in the sensitivity analysis. The impact of changing the constraint of a defined volume of the required design in deterministic problems is examined. Additionally, the impact of altering the reliability index in probabilistic problems is investigated. The effectiveness of the suggested approach is shown using a benchmark problem. Additionally, this research takes into account probabilistic thermoelastic topology optimization for a 2D L-shaped beam problem.

Open Access: Yes

DOI: 10.1007/s10999-023-09641-0

DEM analysis of crushing evolution in cemented granular materials during pile penetration

M. Movahedi Rad M. Amine Benmebarek

Publication Name: Computers and Geotechnics

Publication Date: 2023-09-01

Volume: 161

Issue: Unknown

Page Range: Unknown

Description:

The present study demonstrates that the 3D discrete-element method provides a practical model approach to visualize the cemented grain crushing evolution under pile penetration. A combined method using a rigorous breakage criterion based on octahedral shear stress (OSS) was implemented in the particle flow code PFC3D. First, the pile penetration is simulated by considering the grains as uncrushable with a screening of highly stressed grains exceeding the threshold defined by the OSS failure condition. Then, the simulation is repeated where crushable agglomerates replace the highly stressed grains. This method is more accurate than the replacement method and more efficient than the agglomerate method. A quarter of the numerical model was considered after validation to achieve an acceptable computational time for parametric studies. Parametric investigations were performed on the effects of particle crushing, boundary conditions, pile tip shape, and pile penetration velocity on the penetration resistance behavior. In agreement with the observations of the physical calibration chamber, the present results indicate that the proposed modeling approach is reliable in reproducing the concentration of crushed granular material particles in the vicinity of the pile tip and shaft. In addition, grain crushing has been found to reduce both penetration and shaft resistance.

Open Access: Yes

DOI: 10.1016/j.compgeo.2023.105631

Investigation of the Bearing Capacity of Transport Constructions Made of Corrugated Metal Structures Reinforced with Transversal Stiffening Ribs

Szabolcs Fischer Vitalii Kovalchuk Mykola Sysyn M. Movahedi Rad

Publication Name: Infrastructures

Publication Date: 2023-09-01

Volume: 8

Issue: 9

Page Range: Unknown

Description:

Methods of increasing the bearing capacity of corrugated metal structures of transport constructions using transversal stiffening ribs in the form of additional corrugation and stiffeners are given. Based on the theory of elasticity, a mathematical model for estimating the stress-strain state of transport constructions made of corrugated metal structures reinforced with stiffening ribs in the form of double corrugation was developed. The method of determining equivalent forces during rolling stock passage is offered. It has been established that double corrugation increases the bearing capacity of corrugated metal structures. Therefore, additional corrugation of corrugated metal structures reduces stresses by up to 20% and deflections by 50%. The obtained results show that the increase in rolling stock speed does not lead to a significant increase in stresses and strains in CMS when the railway track corresponds to the design state.

Open Access: Yes

DOI: 10.3390/infrastructures8090131

3D DEM Analysis of Particle Breakage Effect on Direct Shear Tests of Coarse Sand

M. Movahedi Rad M. Amine Benmebarek Sadok Benmebarek

Publication Name: Materials

Publication Date: 2023-07-01

Volume: 16

Issue: 14

Page Range: Unknown

Description:

This paper explores the effect of particle breakage on the mechanical behavior of coarse sand through 3D Discrete Element Method (DEM) simulations of direct shear tests (DST). The objective is to gain insights into the macro- and micro-mechanical behaviors of crushable coarse sand, with a particular focus on the stress–strain relationship, volumetric deformation, and evolution of grain crushing. The simulations involve a comparison between non-crushable and crushable particle models, where the crushable particles are implemented in the shear zone of the DST subjected to different high normal stresses. The findings indicate that the crushable particles experience partial crushing at peak shear stress, with further particle crushing leading to the production of finer particles at the shearing plane during shearing at the critical state. The migration of these finer particles under pressure and gravity generates their accumulation predominantly in the lower section of the simulation box. Importantly, the presence of crushing in the DST induces a decrease in the shear stress and an increase in the volumetric strain leading to contractive behavior instead of dilation, which gradually stabilizes the volumetric deformation at higher normal stresses.

Open Access: Yes

DOI: 10.3390/ma16145025

Optimal Shape Design of Concrete Sleepers under Lateral Loading Using DEM

M. Movahedi Rad Jafar Chalabii Seyedsaber Hosseini

Publication Name: Buildings

Publication Date: 2023-07-01

Volume: 13

Issue: 7

Page Range: Unknown

Description:

Despite the significant contribution of sleepers to the lateral resistance of ballasted tracks, limited research has focused on improving the shape of sleepers in this aspect. This study aims to evaluate proposed sleeper shapes based on the B70 form, utilizing a linear optimization algorithm. First, a DEM model was verified for this purpose using the outcomes of the experiments. Then, using this model, the effect of the weight of the B70 sleeper was carried out on lateral resistance. Next, suggested shapes contacted with ballast materials were applied to lateral force while maintaining the mechanical ballast’s properties until a displacement of 3.5 mm was achieved. The current study’s results showed that the rate of lateral resistance increasing becomes lower for weights higher than 400 kg. Additionally, it was demonstrated that the sleeper’s weight will not always increase lateral resistance. The findings also indicated that although some proposal shapes had higher lateral resistance in comparison to other forms, these designs are not practical from an economic standpoint. Furthermore, despite the lower weight of some other suggested shapes in comparison with B70, the lateral resistances are 31.2% greater. As a result, it is possible to recommend employing a proposed sleeper rather than a B70 sleeper.

Open Access: Yes

DOI: 10.3390/buildings13071574

An Investigation of the Recent Developments in Reliability-based Structural Topology Optimization

M. Movahedi Rad Muayad Habashneh

Publication Name: Periodica Polytechnica Civil Engineering

Publication Date: 2023-06-16

Volume: 67

Issue: 3

Page Range: 765-774

Description:

Optimizing a structure's topology involves finding the best possible distribution of material and connections within a given design space. It has a significant effect on its performance, which is why there has been a meteoric rise in the number of articles published on the topic over the last two decades. This work offers an investigation of reliability-based topology optimization of structures, in light of the recent development of several topology optimization techniques for both linear and nonlinear systems. Therefore, the emphasis of this study is on the latest advancements, enhancements, and applications of reliability-based topology optimization. This paper's primary objective is to provide an overview of the latest advancements in the reliability-based topology optimization of structures, with a particular emphasis on the recent improvement of integrating reliability-based design into the bi-directional evolutionary structural optimization (BESO) method, which accounts for the topological optimization of geometric and material nonlinearity as well as thermoelastic problems.

Open Access: Yes

DOI: 10.3311/PPci.22107

Optimal Plastic Reliable Design of Reinforced Concrete Beams Considering Steel Bars Volume Probability

M. Movahedi Rad Sarah Khaleel Ibrahim

Publication Name: Mathematics

Publication Date: 2023-05-01

Volume: 11

Issue: 10

Page Range: Unknown

Description:

This paper aims to investigate the plastic response of reinforced concrete tapered beams when subjected to random steel reinforcement volumes, using both deterministic and probabilistic analyses, with the complementary strain energy as a boundary in the first case, and the reliability index as a boundary in the second. The first step in this study was to use a previously studied model and perform a deterministic analysis, assuming that the complementary strain energy is a limiting factor and controller of the plastic behaviour. Next, a probabilistic analysis is applied, with the reliability index as a limitation. At the same time, the volume of the reinforcement steel used, and the complementary strain energy were treated as probabilistic variables with mean values and specific standard deviations. This novel method highlighted the plastic behaviour limiting procedure and provided results that highlighted the nature of the model’s changed behaviour when the complementary strain energy was controlled and when applying probabilistic properties with reliability index limitation.

Open Access: Yes

DOI: 10.3390/math11102349

Experimental and Numerical Analysis of Steel-Polypropylene Hybrid Fibre Reinforced Concrete Deep Beams

Noor Abbas Hadi M. Movahedi Rad Sarah Khaleel Ibrahim

Publication Name: Polymers

Publication Date: 2023-05-01

Volume: 15

Issue: 10

Page Range: Unknown

Description:

This work experimentally and numerically explored how varied steel-polypropylene fibre mixtures affected simply supported reinforced concrete deep beams. Due to their better mechanical qualities and durability, fibre-reinforced polymer composites are becoming more popular in construction, with hybrid polymer-reinforced concrete (HPRC) promising to increase the strength and ductility of reinforced concrete structures. The study evaluated how different combinations of steel fibres (SF) and polypropylene fibres (PPF) affected beam behaviour experimentally and numerically. The study’s focus on deep beams, research of fibre combinations and percentages, and integration of experimental and numerical analysis provide unique insights. The two experimental deep beams were the same size and were composed of hybrid polymer concrete or normal concrete without fibres. Fibres increased deep beam strength and ductility in experiments. The calibrated concrete damage plasticity model in ABAQUS was used to numerically calibrate HPRC deep beams with different fibre combinations at varied percentages. Based on six experimental concrete mixtures, calibrated numerical models of deep beams with different material combinations were investigated. The numerical analysis confirmed that fibres increased deep beam strength and ductility. HPRC deep beams with fibre performed better than those without fibres in numerical analysis. The study also determined the best fibre percentage to improve deep beam behaviour where a combination of 0.75% SF and 0.25% PPF was recommended to enhance load-bearing capacity and crack distribution, while a higher content of PPF was suggested for reducing deflection.

Open Access: Yes

DOI: 10.3390/polym15102340

Study of Bonding between Façade Stones and Substrates with and without Anchorage Using Shear-Splitting Test—Case Study: Travertine, Granite, and Marble

Amin Ghodousian Oveys Ghodousian M. Movahedi Rad Vahid Shafaie Sina Hajiloo

Publication Name: Buildings

Publication Date: 2023-05-01

Volume: 13

Issue: 5

Page Range: Unknown

Description:

This paper presents an investigation into the bond strength of three common façade stones, namely, travertine, granite, and marble, to a concrete substrate using a shear-splitting test. The effects of anchorage, the number of curing days, and the presence of an anti-freezing agent in cement–sand mortar on bond strength were studied. The results show that the number of curing days had a significant impact on the bond strength between the stones and the substrates. The presence of an anti-freezing agent and accelerator increased bonding during the initial days, but this effect gradually decreased. The use of anchorage had a positive effect on the bond strength, particularly with fewer curing days. Granite had the lowest bond strength when no anchorage was used due to its low permeability. Based on the findings, a novel fuzzy logic approach was proposed to predict the bond strength. This study provides valuable insights into improving the bonding of façade stones to substrates and can aid in the safe and efficient use of these materials in construction.

Open Access: Yes

DOI: 10.3390/buildings13051229

Optimal Elasto-Plastic Analysis of Prestressed Concrete Beams by Applying Residual Plastic Deformation Limitations

M. Movahedi Rad Sarah Khaleel Ibrahim

Publication Name: Sustainability Switzerland

Publication Date: 2023-04-01

Volume: 15

Issue: 7

Page Range: Unknown

Description:

This work introduces elasto-plastic analysis of prestressed reinforced concrete beams under different prestressing conditions by limiting the residual plastic behaviour inside the steel bars using complementary strain energy. A non-linear optimal method was used to limit residual plastic deformations in steel bars, including prestressed tendons, used to reinforce beams from two previous research investigations. This was considered by using an optimization approach with an objective function to find the maximum loading while applying constraints on the complementary strain energy of residual internal forces in steel elements to control residual plastic deformations. Thus, an elasto-plastic optimization programme was linked to models simulated by ABAQUS, as concrete was calibrated by the concrete damage plasticity (CDP) model. Some variables were considered regarding the force applied inside prestressed tendons and the number of tendons used inside the models. Thus, limits on complementary strain energy affected load values and model damage where an increase in the permissible strain energy value leads to an increase in the corresponding loading values produced; thus, this produces a higher stress intensity in steel and tension-damaged areas in concrete. Based on these data, many comparisons have been made to determine when beams behaved elastically and how they turned into plastic.

Open Access: Yes

DOI: 10.3390/su15075742

Reliability Assessment of Reinforced Concrete Beams under Elevated Temperatures: A Probabilistic Approach Using Finite Element and Physical Models

J. Szép János Lógó M. Movahedi Rad Muayad Habashneh

Publication Name: Sustainability Switzerland

Publication Date: 2023-04-01

Volume: 15

Issue: 7

Page Range: Unknown

Description:

A novel computational model is proposed in this paper considering reliability analysis in the modelling of reinforced concrete beams at elevated temperatures, by assuming that concrete and steel materials have random mechanical properties in which those properties are treated as random variables following a normal distribution. Accordingly, the reliability index is successfully used as a constraint to restrain the modelling process. A concrete damage plasticity constitutive model is utilized in this paper for the numerical models, and it was validated according to those data which were gained from laboratory tests. Detailed comparisons between the models according to different temperatures in the case of deterministic designs are proposed to show the effect of increasing the temperature on the models. Other comparisons are proposed in the case of probabilistic designs to distinguish the difference between deterministic and reliability-based designs. The procedure of introducing the reliability analysis of the nonlinear problems is proposed by a nonlinear code considering different reliability index values for each temperature case. The results of the proposed work have efficiently shown how considering uncertainties and their related parameters plays a critical role in the modelling of reinforced concrete beams at elevated temperatures, especially in the case of high temperatures.

Open Access: Yes

DOI: 10.3390/su15076077

Effect of Rolling Resistance Model Parameters on 3D DEM Modeling of Coarse Sand Direct Shear Test

M. Movahedi Rad M. Amine Benmebarek

Publication Name: Materials

Publication Date: 2023-03-01

Volume: 16

Issue: 5

Page Range: Unknown

Description:

This paper deals with the micro and macro behaviors of coarse sand inside a direct shear box during a geotechnical test. A 3D discrete element method (DEM) model of the direct shear of sand was performed using sphere particles to explore the ability of the rolling resistance linear contact model to reproduce this commonly used test considering real-size particles. The focus was on the effect of the interaction of the main contact model parameters and particle size on maximum shear stress, residual shear stress, and sand volume change. The performed model was calibrated and validated with experimental data and followed by sensitive analyses. It is shown that the stress path can be reproduced appropriately. For a high coefficient of friction, the peak shear stress and volume change during the shearing process were mainly affected by increasing the rolling resistance coefficient. However, for a low coefficient of friction, shear stress and volume change were marginally affected by the rolling resistance coefficient. As expected, varying the friction and rolling resistance coefficients was found to have less influence on the residual shear stress.

Open Access: Yes

DOI: 10.3390/ma16052077

Numerical Investigation of Pre-Stressed Reinforced Concrete Railway Sleeper for High-Speed Application

Szabolcs Fischer Zoltán Major Szabolcs Szalai Mykola Sysyn Attila Németh Dmytro Kurhan Dóra Harangozó M. Movahedi Rad Sarah Khaleel Ibrahim Dániel Harrach Szabolcs Kocsis Szurke Gusztáv Baranyai Géza Herczeg L. Gaspar

Publication Name: Infrastructures

Publication Date: 2023-03-01

Volume: 8

Issue: 3

Page Range: Unknown

Description:

The current paper deals with the numerical investigation of a unique designed pre-stressed reinforced concrete railway sleeper for the design speed of 300 km/h, as well as an axle load of 180 kN. The authors applied different methodologies in their research: traditional hand-made calculations and two types of finite element software. The latter were AxisVM and ABAQUS, respectively. During the calculations, the prestressing loss was not considered. The results from the three methods were compared with each other. The hand-made calculations and the finite element modeling executed by AxisVM software are adequate for determining the mechanical inner forces of the sleeper; however, ABAQUS is appropriate for consideration of enhanced and sophisticated material models, as well as the stress-state of the elements, i.e., concrete, pre-stressed tendons, etc. The authors certified the applicability of these methodologies for performing the dimensioning and design of reinforced concrete railway sleepers with pre-stressing technology. The research team would like to continue their research in an improved manner, taking into consideration real laboratory tests and validating the results from FE modeling, special material models that allow calculation of crackings and their effects in the concrete, and so that the real pattern of the crackings can be measured by GOM Digital Image Correlation (DIC) technology, etc.

Open Access: Yes

DOI: 10.3390/infrastructures8030041

Limited Optimal Plastic Behavior of RC Beams Strengthened by Carbon Fiber Polymers Using Reliability-Based Design

M. Movahedi Rad Sarah Khaleel Ibrahim

Publication Name: Polymers

Publication Date: 2023-02-01

Volume: 15

Issue: 3

Page Range: Unknown

Description:

The plastic behavior of strengthened haunched beams utilizing carbon fiber-reinforced polymers (CFRP) was investigated using a probabilistic design that took into account random concrete properties, CFRP properties, and complementary strain energy values, with the reliability index serving as a limiting index, as the proposed method considers a novel method that deals with probabilistic parameters for models with limited plastic behavior designed based on the reliability index. The data used in this research were gathered and evaluated in a recent study on simply supported haunched beams reinforced with carbon fiber-reinforced polymers. The purpose of this research was to use the reliability limitation index for simulated strengthened haunched beams by taking into account randomness in concrete and CFRP properties and the complementary strain energy value, which is considered a plastic behavior controller that provides an illustration of the damage amount within the reinforcement steel bars. The results indicate how randomness affects the behavior of the presented models, which are chosen to have different numbers of CFRP strips. The variable randomness affects load and deflection values where the reliability index value increases as the corresponding load value decrease, reflecting the increased probability of failure in models subjected to higher loading conditions, while tension concrete damage percentages are reflected in the damage pattern presented in the results, showing that as the produced load increases, so does the damage intensity. It is also obvious that the reliability index served as a limitation index while taking concrete characteristics and complementary strain energy as random variables.

Open Access: Yes

DOI: 10.3390/polym15030569

Examination of Concrete Canvas under Quasi-Realistic Loading by Computed Tomography

Szabolcs Fischer I. Fekete Szabolcs Szalai Mykola Sysyn Dmytro Kurhan M. Movahedi Rad Dániel Harrach B. Eller Gusztáv Baranyai

Publication Name: Infrastructures

Publication Date: 2023-02-01

Volume: 8

Issue: 2

Page Range: Unknown

Description:

The current paper concerns the investigation of CC (Concrete Canvas), a unique building material from the GCCM (geosynthetic cementitious composite mat) product group. The material is suitable for trench lining, trench paving, or even military construction activities, while the authors’ purpose is to investigate the application of the material to road and railway substructure improvement. This research was carried out to verify the material’s suitability for transport infrastructure and its beneficial effects. The authors’ previous study reported that the primary measurements were puncture, compression, and the parameters evaluated in four-point bending (laboratory) tests. However, based on the results, finite element modeling was not feasible because the testing of the composite material in a single layer did not provide an accurate indication. For this reason, the material characteristics required for modeling were investigated. A unique, novel testing procedure and assembly were performed, wherein the material was loaded under quasi-realistic conditions with a crushed stone ballast sample and other continuous particle size distribution samples in a closed polyethylene tube. In addition, the deformation of the material following deformed bonding was measured by computed tomography scanning, and the results were evaluated.

Open Access: Yes

DOI: 10.3390/infrastructures8020023

Bi-directional Evolutionary, Reliability-based, Geometrically Nonlinear, Elasto-Plastic Topology Optimization, of 3D Structures

Szabolcs Fischer M. Movahedi Rad Muayad Habashneh

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2023-01-01

Volume: 20

Issue: 1

Page Range: 169-186

Description:

An extension of bi-directional evolutionary structural optimization, by considering three-dimensional geometrically nonlinear reliability-based elasto-plastic topology optimization, is presented in this study. Due to the important role of the existence of uncertainties to make structural design more practical, this study considers the reliability-based design. Thus, for probabilistic purposes, volume fraction is considered random. The reason of considering the volume fraction as random variable that the application of reliability-based topology optimization shows different topological results comparing to those which are obtained through deterministic designs. By adopting Monte-Carlo technique, the reliability indices are calculated based on the failure probabilities. Different values of volume fractions are considered to explore the effect of changing it on the resultant topologies in case of deterministic design. Furthermore, study the influence of considering different values of reliability indices on the results of probabilistic designs. The plastic-limit analysis is considered in this study in case of elasto-plastic models. A 3D elasto-plastic L-shape beam is considered as a benchmark problem to demonstrate the proficiency of the proposed method. In addition, 3D cantilever beam is considered for deterministic and probabilistic topology optimization designs in cases of elastic and elasto-plastic materials.

Open Access: Yes

DOI: 10.12700/APH.20.1.2023.20.12

Numerical Investigation of Glue Laminated Timber Beams considering Reliability-based Design

M. Movahedi Rad Dániel Harrach Muayad Habashneh

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2023-01-01

Volume: 20

Issue: 1

Page Range: 109-122

Description:

Structural models and their related parameters, are most often considered as deterministic, in numerical analysis. However, according to test results, one can see the existence of uncertainties, in most cases, due to various reasons, such as, natural variabilities and ignorance. Thus, dealing with uncertainty has gained massive attention, due to its importance in structural analysis and anticipating the performance of models. In fact, in some cases of special structure components, like glue laminated timber beams, it appears to be, that there is an absence of information concerning uncertainties. Therefore, the main objective of this study is to inspect uncertainties that facing designers and their role in glue laminated timber beams behavior, by considering different material parameters as random variables. In addition, four-point bending tests are conducted and finite element analysis is conducted, using ABAQUS software, to model the nonlinear behavior of GLT beams. For purposes of numerical model calibration, Hill yield criterion constitutive model is considered based on the obtained data from the experimental test. The results of this study provide a better outline for understanding the effect of uncertainties on glue laminated timber beams.

Open Access: Yes

DOI: 10.12700/APH.20.1.2023.20.8

Comprehensive Laboratory Test Series for Timber-Concrete Composite Structures

M. Movahedi Rad Dániel Harrach

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2023-01-01

Volume: 20

Issue: 1

Page Range: 231-250

Description:

Timber-concrete composite structures are not as widespread as traditional steel-concrete fabrications; this structural design still has many critical points that require tests on laboratory specimens. This paper presents the complex testing process of timber-concrete composite structures, which must be followed from the investigation of the possibilities of connecting timber and concrete to each other, through the tests of bended beams acting as timber-concrete composites, to the laboratory tests of full-scale custom-designed timber-concrete composite bridge structures subjected to both concentrated and distributed loads. In this study, to improve the flexural properties of timber beams, carbon fiber-reinforced polymer (CFRP) laminates are attached externally to timber elements. To verify the behavior of the designed structure, we built a full-scale experimental structure and performed a load test. In the laboratory tests, the serviceability limit states, standard loads and load arrangements were investigated. The results of the loading experiments were evaluated. The bridge structures in this article will be placed outdoors after completion of the tests, where they will be used as pedestrian-bicycle bridges. In the case of the examined structures, it was an important aspect, to use elements that are commercially available and suitable for use in the Hungarian design and regulatory systems.

Open Access: Yes

DOI: 10.12700/APH.20.1.2023.20.16

Optimal Elasto-Plastic Analysis of Reinforced Concrete Structures under Residual Plastic Deformation Limitations

Szabolcs Fischer M. Movahedi Rad Sarah Khaleel Ibrahim

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2023-01-01

Volume: 20

Issue: 1

Page Range: 45-62

Description:

In this study, an investigation regarding optimal elastic-plastic analysis method of different reinforced concrete (RC) structures is held by applying the residual plastic deformations limitations on the steel bars inside the reinforced concrete. Where different structures, including simple beam and slab, are selected as benchmarks and modelled numerically using ABAQUS in order to calibrate their experimental behaviour according to laboratory tests. Furthermore, concrete damage plasticity (CDP) constitutive model was applied to represent concrete behaviour in the numerical models considered. Then, an objective function was established for optimizing the applied plastic loads for each structure where the process of controlling plastic deformations was carried out by applying constraints on the complementary strain energy of the residual internal forces initiated inside the steel bars. This methodology was applied by authors by writing MATLAB code and linking it with ABAQUS to determine the corresponding applied plastic load for each entered complementary strain energy. Generally, applying optimization problem for each model showed that the complementary strain energy of the residual forces reflects the general behaviour of the structures and may be assumed as a constraint controlling the plastic behaviour of the structures whereas the obtained results indicated how structures acted differently when possessing different complementary strain energy values turning from elastic into elasto-plastic condition and then reaching plastic state.

Open Access: Yes

DOI: 10.12700/APH.20.1.2023.20.4

Optimizing Topology of Structures Considering Fatigue-Resistance

M. Movahedi Rad Muayad Habashneh

Publication Name: Chemical Engineering Transactions

Publication Date: 2023-01-01

Volume: 107

Issue: Unknown

Page Range: 613-618

Description:

The pursuit of reliable design has become increasingly crucial in various engineering disciplines, aiming to minimize environmental impact and enhance resource efficiency. In this context, this study explores the integration of topology optimization techniques with fatigue analysis to develop reliable designs for structural components. Fatigue failure is a critical concern in engineering applications, as it significantly affects the lifespan and reliability of structures. The proposed methodology combines mathematical optimization algorithms, computational modeling, and fatigue analysis techniques. The primary objective of this study is to minimize structural weight by determining the optimal material arrangement within the design domain while also considering fatigue as a constraint within the optimization problem. The bi-directional evolutionary structural optimization (BESO) method is developed to meet the goal of this research. Furthermore, topology optimization of L-shape and U-plate problems are considered as numerical examples to demonstrate the effectiveness of the suggested method. By considering fatigue behavior in topology optimization, engineers can develop lightweight and durable structures that effectively utilize materials while minimizing resource utilization. The integration of these two fields opens up new avenues for reliable design, promoting resource efficiency and contributing to the overall reliability of engineering practices.

Open Access: Yes

DOI: 10.3303/CET23107103

Advanced Numerical Simulation and Modeling of Welding Processes: Stochastic representation of parameters for Improved Fabrication

J. Szép M. Movahedi Rad Muayad Habashneh Daniel Gosztola Péter Grubits

Publication Name: Chemical Engineering Transactions

Publication Date: 2023-01-01

Volume: 107

Issue: Unknown

Page Range: 619-624

Description:

Numerical simulations play a pivotal role in advancing fabrication processes and welding technologies, enabling the pursuit of sustainable practices. By employing the finite element method, crucial insights regarding welded specimens can be derived, encompassing deformed shapes, residual stresses, and even microstructural properties such as phase proportions and hardness. This study focuses on the modeling framework of welding processes, emphasizing the influence of various welding parameters on sustainable outcomes, including reduced environmental impact and enhanced resource efficiency. The investigation delves into the characterization of heat sources, accounting for temperature-dependent material properties and developing a comprehensive thermo-mechanical analysis. By incorporating sustainability considerations and utilizing our Finite Element (FE) model, we conducted further analysis to elucidate the stability behavior, aligning with sustainable objectives. By considering welding current, arc voltage, and welding speed as random variables with mean values and standard deviations, the study aims to identify a model that effectively accounts for the inherent randomness of the welding process. This research contributes to the growing body of knowledge on sustainable welding practices by merging numerical simulations, advanced modeling techniques, and sustainability principles. The outcomes of this study have the potential to inform industry stakeholders and decision-makers about the most effective strategies for achieving sustainable welding processes and minimizing the ecological footprint of the welding operations.

Open Access: Yes

DOI: 10.3303/CET23107104

Research on Risk Control Parameters of a Shielded-Tunnel-enlarged Station, based on Bearing Capacity of Pre-removed Segment

Weining Liu Zhiyong Peng Xiuren Yang M. Movahedi Rad

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2023-01-01

Volume: 20

Issue: 1

Page Range: 213-229

Description:

A pre-removed segment is a new structure segment applicable to enlarging shield tunnel technology. It can facilitate the removal of the excess partitioned segment, for an enlarged station, by shield tunnel, however, it may cause certain risk of enlarged excavation construction, when a certain construction control limit is exceeded. To study the risk control problem for the removed segment, applicable to the shielded-tunnel-enlarged station, a risk control method, based on the load critical curve of the pre-removed segment is proposed. In this paper, a three-dimensional stratum structure model of the shielded-tunnel-enlarged station is established and variations of forces on the interface of the pre-removed segment are analyzed, under the influences of buried depth and staggered distance, for different enlarged excavation construction stages, as well as different soil properties (elasticity modulus). Combined with the load critical curve of the contact surface concerning the pre-removed segment obtained from the test, the critical construction control surface of buried depth and staggered distance, was obtained to ensure the bearing capacity of the pre-removed segment in different soil properties and in all of the involved enlarged excavation stages. It provides the technical guidance and reference for the construction risk control of the application of pre-removed segment in the shielded-tunnel-enlarged station.

Open Access: Yes

DOI: 10.12700/APH.20.1.2023.20.15

Reliability-based numerical analysis of glulam beams reinforced by CFRP plate

M. Movahedi Rad Dániel Harrach Muayad Habashneh

Publication Name: Scientific Reports

Publication Date: 2022-12-01

Volume: 12

Issue: 1

Page Range: Unknown

Description:

Most existed researches consider deterministic numerical analysis when dealing with structural models. However, the test results reveal that uncertainties are existing in most cases regarding some considerations such as material randomness and the lack of experience. Therefore, proposing a probabilistic design models have got attention of researchers according to its important role in predicting accurate performance of the structures. The aim of the proposed work is to consider reliability-based analysis in numerical modelling of glulam beams reinforced with CFRP plates as well as unreinforced glulam beams by considering the properties of used timber material as random variables having mean value and standard deviation taking into consideration that the findings of this study have shown that the reliability index is worked efficiently as a limit which controls the process. Hill yield criterion model is adopted with respect to the data which is obtained from the experimental tests in order to validate the models. Furthermore, a detailed comparison between the reinforced and unreinforced glulam beams are proposed to see the effect of introducing the CFRP plates as a reinforcement material. The results of this study have successfully given a deep understanding of how the uncertainties plays a crucial role on the resulted deformations and stresses in which it was founded by making a comparison between deterministic and probabilistic numerical analysis.

Open Access: Yes

DOI: 10.1038/s41598-022-17751-6

Reliability based geometrically nonlinear bi-directional evolutionary structural optimization of elasto-plastic material

M. Movahedi Rad Muayad Habashneh

Publication Name: Scientific Reports

Publication Date: 2022-12-01

Volume: 12

Issue: 1

Page Range: Unknown

Description:

The aim of this paper is to integrate the reliability-based analysis into topology optimization problems. Consequently, reliability-based topology optimization (RBTO) of geometrically nonlinear elasto-plastic models is presented. For purpose of performing (RBTO), the volume fraction is considered reliable since that the application of (RBTO) gives different topology in comparison to the deterministic topology optimization. The effects of changing the prescribed total structural volume constraint for deterministic designs and changing the reliability index for probabilistic designs are considered. Reliability index works as a constraint which is related to reliability condition added into the volume fraction and it is calculated using the Monte-Carlo simulation approach in the case of probabilistic design. In addition, bi-directional evolutionary structural optimization (BESO) method is utilized to study the effect of geometrically nonlinear elasto-plastic design. The plastic behavior can be controlled by defining a limit on the plastic limit load multipliers. The suggested work's efficiency is demonstrated via a 2D benchmark problem. In case of elastic material, a 2D model of U-shape plate is used for probabilistic design of linear and geometrically nonlinear topology optimizations. Furthermore, a 2D elasto-plastic model is considered for reliability-based design to demonstrate that the suggested approach can determine the best topological solution.

Open Access: Yes

DOI: 10.1038/s41598-022-09612-z

Effect of Sleeper-Ballast Particle Contact on Lateral Resistance of Concrete Sleepers in Ballasted Railway Tracks

M. Movahedi Rad Jafar Chalabii Ebrahim Hadizadeh Raisi Reza Esfandiari Mehni

Publication Name: Materials

Publication Date: 2022-11-01

Volume: 15

Issue: 21

Page Range: Unknown

Description:

Although a sleeper makes a great contribution to the lateral resistance of ballasted tracks, in this regard, limited studies have been carried out on the effect of its contact surface with ballast aggregates. The current paper is dedicated to evaluating the effect of sleeper shape on the lateral resistance of ballasted track through discrete element modelling (DEM). For this purpose, firstly, a DEM model was validated based on the experimental results. Then, a sensitivity analysis was undertaken on the effect of the different contact areas that a standard concrete sleeper faces with the crib, shoulder and underlying ballast aggregates on lateral resistance of a single sleeper. As the main result of the current study, a high accurate regression equation for constant weight 319.2 kg and constant density 2500 kg/m3 of the sleepers was fitted between different sleeper contact areas and the maximum lateral resistance of a concrete sleeper for 3.5 mm lateral displacement in ballasted railway tracks. The obtained results showed that the effect of the sleeper’s head area compared to the underlying area of the sleeper and the head area of the sleeper compared to the sleeper’s side area in terms of lateral resistance are 8.2 times and 14.5 times more, respectively.

Open Access: Yes

DOI: 10.3390/ma15217508

Ballast Stabilization with Polyurethane for Use in Desert Areas

Jabbar Ali Zakeri Morteza Esmaeili Farshad Astaraki M. Movahedi Rad Sina Ghahremani Reza Esfandiari Mehni Fateme Samimi

Publication Name: Periodica Polytechnica Civil Engineering

Publication Date: 2022-06-30

Volume: 66

Issue: 3

Page Range: 853-865

Description:

Sand dune accumulation in the railways passing through desert areas leads to ballast softening and settlement, which is one of the major challenges in the ballast maintenance operation. In this regard, ballast infilling with polyurethane could be mentioned as a novel solution that has been less attentional in previous studies. In this matter, in present study using a domestic cost-effective polyurethane, the ballast stabilization has been accomplished and the relevant shear strength parameters have been investigated via a series of large-scale direct shear tests. Since the utilized polyurethane has composed of two different components, in the first stage, the best weight ratios of components have been investigated via a series of compression tests. In this matter, the ratio of 1.5 units polyol to 1 unit isocyanate has been adopted as the best composition. Then, the resulting polyurethane was injected into the ballast to perform large-scale direct shear tests. According to the measurement results, the maximum shear stress, the internal friction angle, and the cohesion coefficient increased by 109%, 9.5%, and 162.5% with respect to the non-stabilized ballast (NSB), respectively. In addition, the dilation angle decreased by 66.4% with the injection of polyurethane into the ballast. Hence, the results indicate increased shear strength and lateral track resistance in the presence of polyurethane, which can prevent lateral deflection and improve track safety. In other words, the mentioned polyurethane has improved the shear parameters of the ballast more significantly than other polyurethanes and has shown its performance in increasing the bearing capacity.

Open Access: Yes

DOI: 10.3311/PPci.19968

Limit design of reinforced concrete haunched beams by the control of the residual plastic deformation

János Lógó M. Movahedi Rad Sarah Khaleel Ibrahim

Publication Name: Structures

Publication Date: 2022-05-01

Volume: 39

Issue: Unknown

Page Range: 987-996

Description:

In this paper, a novel computational (optimization) model is presented to control the plastic behaviour of reinforced concrete haunched beams using complementary strain energy of residual forces formed inside the steel reinforcing bars. For this purpose, a numerical model validation process was held and then two non-linear optimization problems were outlined. In these optimization problems, different objective functions were considered applying the optimal elasto-plastic analysis and design of haunched reinforced concrete beams aiming to find the maximal loading or the minimum volume of the steel used to reinforce the beams as the plastic deformations are controlled by using constraints on the complementary strain energy of the residual internal forces of the steel bars. Moreover, the effect of these constraints on different haunch angle beams is studied. The applied method is described in terms of nonlinear mathematical programming and providing solutions when the plastic reserves of the body are not fully exhausted. It is worth mentioning that in this study a concrete damage plasticity constitutive model is applied in the numerical problems and calibrated in accordance with the data gained from laboratory tests. The optimal solutions of the nonlinear mathematical problems were calculated by MATLAB programming codes written by the authors taking into consideration different objective functions and equality and inequality constraints for each case. Finally, by performing a parametric study, the different optimization problems showed how beams behaved differently under different complementary strain energy limit values shifting from elastic into elasto-plastic state and then reaches the fully plastic state where results showed different comparisons taking into consideration the effect of the different complementary strain energy limit values on the maximum applied load, geometry of the beam and steel volume used to reinforce the beams. Thus, complementary strain energy limit value is used to control the plastic deformation inside steel bars during loading progress where avoiding the formation of the plastic deformation in the steel bars would reflect on the general behaviour of the haunched reinforced concrete beams.

Open Access: Yes

DOI: 10.1016/j.istruc.2022.03.080

Investigation of the Track Gauge in Straight Sections, Considering Hungarian Railway Lines

Szabolcs Fischer Attila Németh M. Movahedi Rad Henriett Horváth Dalma Németh

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2022-01-01

Volume: 19

Issue: 3

Page Range: 155-166

Description:

In this work, considering the MÁV’s (i.e., the Hungarian Railways) five small and five high-traffic railway lines, the statistical distribution and change of the track gauge parameter were analyzed, under a ten year, on time-series analysis, related to straight track sections. The analysed data, were bottom track gauge measurements, of the FMK-004 and FMK-007 type railway track geometry, measuring and recording car & wagon. Taking into account the railway tracks, the track gauge parameter cannot be controlled and improved upon by large machine methods, but its permitted value depends on the allowed speed (and vice versa). The main independent variables were the elapsed time and the through-rolled axle tons (as a function of time, i.e., the MGT). To generate the statistical analyses, Vaszary-like shape numbers were computed, considering the distribution functions of the measured data series of the track gauge parameter every 25 cm. The authors examined the change of the shape numbers, the average and standard deviation values of the track gauge, and the shape of the distribution functions (skewness and kurtosis properties). In the end, a spectrum analysis of the measured data series was produced. In conclusion, the Authors provide relevant statements regarding the track gauge parameter.

Open Access: Yes

DOI: DOI not available

Laboratory Tests and FE Modeling of the Concrete Canvas, for Infrastructure Applications

Szabolcs Fischer M. Movahedi Rad B. Eller

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2022-01-01

Volume: 19

Issue: 3

Page Range: 9-20

Description:

The Concrete Canvas (CC) material, is a promising material for application in many civil engineering fields, such as, water construction, pipelining, slope protection, military applications, etc. The authors believe that this material has more potential and could be helpful in infrastructure applications. The infrastructure design requirements are known; the CC has to be fit into the track structure. Several relevant investigations were performed to show the materials adequacy, and using collected data, FE (Finite Element) models were built to determine more of the physical parameters. From the results and the hardening experiences, it can be stated, that after the laying of CC and the spraying of water, the material has to be loaded to reach the best shape and push the material down to the supporting protection layer. In FE modeling, it was shown that the material is a composite structure, i.e. one material's physical properties is not enough for modeling (it has to be improved). Moreover, it means that dynamic examinations can be initiated.

Open Access: Yes

DOI: DOI not available

Investigation of deformations of ballasted railway track during collapse using the Digital Image Correlation Method (DICM)

Szabolcs Fischer Szabolcs Szalai Attila Németh Erika Juhasz M. Movahedi Rad Dániel Harrach B. Eller Gusztáv Baranyai

Publication Name: Reports in Mechanical Engineering

Publication Date: 2022-01-01

Volume: 3

Issue: 1

Page Range: 168-191

Description:

This paper summarizes the results of laboratory tests in which the authors investigated the effects of extremely high vertical load to a railway track segment. The segment consisted of a cut concrete sleeper (contact area: 290×390 mm) with a pair of direct-elastic rail fasteners; the sleeper pieces had a standard, full height; the structure had a typical 350 mm depth railway ballast, underneath approx. 200 mm sandy gravel supplementary layer. The whole assembly was built in a 2.00×2.20 m area wooden rack. The deformations due to the approx. 150 kN static concentrated vertical force were measured and recorded by Digital Image Correlation Method (DICM), ensuring the GOM ATOS technology. The 150 kN peak load meant 1326 kPa vertical stress at the sleeper-ballast interface. The 3D geometry was scanned before the loading and after the collapse. In this way, the comparison was able to be executed. The maximum vertical deformation was 115 mm. The DICM technique is a relatively new methodology in civil engineering; however, it has been applied for more than ten years in mechanical engineering. Therefore, the authors investigated the applicability of DICM in this field. As a result, the pre and the post-states were determined in 3D. The displacement of the ballast particles was able to be defined with the possibility of drawing the displacement trajectories of given points. The DICM can be a valuable methodology in railway engineering, e.g., laboratory tests and field test applications.

Open Access: Yes

DOI: 10.31181/rme20016032022s

Investigating Slope Stability of Geocell-Reinforced Railway Embankments

Morteza Esmaeili Farshad Astaraki M. Movahedi Rad Mohammad Reza Roozbini

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2022-01-01

Volume: 19

Issue: 6

Page Range: 197-212

Description:

The current paper aims to investigate stability of side’s slops of geocell-reinforced railway embankments. For this purpose, firstly a set of six 1:20 scaled models including a reference embankment and geocell-reinforced embankments was constructed in a loading chamber and their load-settlement behaviour was assessed. In the next stage, 3D FEM models of the embankments were developed and the relevant results were verified against the laboratory test outcomes. In continue, on the basis of verified models, the scaled up railway embankments were simulated and the real train loading applied to the models. In this matter, a wide-ranging parametric study was performed on the embankment soil properties ranged from poor (ST1) to high strength (ST5) materials, geocell elasticity modulus (E), number of geocell layers (N) and their vertical location in the embankment body (U) to achieve a minimum embankment sliding safety factor (SF) of 1.5. Outcomes indicate that geocell opening size, stiffness and the placement position play an important role where the concern is to stabilize the embankments' sides slopes. It was found that middle of the embankment was the best position of geocell layers. Elasticity modulus of 1400 MPa and opening size of 245*210 mm were also determined as the optimum for geocell layers.

Open Access: Yes

DOI: 10.12700/APH.19.6.2022.6.14

Pile optimization in slope stabilization by 2D and 3D numerical analyses

M. Movahedi Rad M. Amine Benmebarek R. P. Ray Sadok Benmebarek

Publication Name: International Journal of Geotechnical Engineering

Publication Date: 2022-01-01

Volume: 16

Issue: 2

Page Range: 211-224

Description:

In this paper, numerical computations using PLAXIS 2D and 3D have been conducted to optimize a row of piles in cohesive-frictional slope stabilization. First, 2D parametric studies were performed to identify both the optimal location and length of the pile as well as the effect of pile head conditions. Next, more rigorous parametric studies taking account of the exact geometry was carried out using 3D analyses. According to the obtained results, the fixed pile head located at the slope middle better improves the stability and reduces the optimal length of the pile. Piles with free head contribute marginally to the increased factor of safety of cohesive-frictional slope. In 3D analyses, it is shown that spacing ratio beyond S/D = 4 (S: pile spacing, D: diameter of the pile), the soil will flow between piles leading to a total vanish of the arching effect when S/D exceeds 12. Comparing the results, the limitation of 2D analysis for piled cohesive-frictional slope is highlighted.

Open Access: Yes

DOI: 10.1080/19386362.2021.1972628

Modification of Concrete Railway Sleeper Mix Design, Using a Hybrid Application of Steel Fibers

Guoqing Jing Farshad Astaraki Mohammad Siahkouhi M. Movahedi Rad Sashka Uuganbayar Jun Wang

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2022-01-01

Volume: 19

Issue: 3

Page Range: 119-130

Description:

Concrete railway sleepers have been used for years without an update in production and design, to be compatible with demands for increasing train axle loads and speed. In the current research, concrete railway admixture is modified with consuming (0.5% straight-1.5% hooked), (1.5% straight-0.5% hooked) and (1% straight-1% hooked) steel fibers combinations. Three main mechanical experiments as compressive, flexural and splitting tensile strengths and fresh mortar “flowability” were performed. Results showed that the hybrid of 1% straight and 1% hooked steel fibers shows the optimal performance among other hybrid combinations. This hybrid admixture efficiently improves the compressive, flexural and splitting tensile strengths of the concrete railway sleeper mix design.

Open Access: Yes

DOI: DOI not available

Comparative Study of the Mechanical Behavior of Concrete Railway Sleeper Mix Design, using Waste Rubber and Glass Materials

Szabolcs Fischer Guoqing Jing Farshad Astaraki Mohammad Siahkouhi M. Movahedi Rad Chunchao Li

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2022-01-01

Volume: 19

Issue: 6

Page Range: 213-224

Description:

Waste rubber tires and glass powders, are hazardous materials for the environment. One of the methods to consume them, is their application in railway engineering projects. Rubber and glass materials, in this research, are provided from waste tires and glass bottles. Therefore, a modification is conducted to the concrete railway sleeper mix design, incorporated with waste rubber (R) and glass powder (GP). Three mechanical tests, including compressive, flexural and tensile splitting, have been studied on rubber and glass powder concrete specimens. Three different percentages of 5%, 10% and 15% by cement weight, for GP and by fine aggregate volume for R, are investigated herein. The results show that GP concrete has a better performance over the rubber concrete (RC), but lower than Ref. specimens. 5%GP as the best mix design, has compressive, flexural and tensile strengths of 45.4 MPa, 7.5 MPa and 5.82 MPa, respectively. Moreover, these strengths, for compressive and flexural, of 5%GP are about 24% and 6% lower than the Ref. strengths, respectively, while, tensile splitting strength is almost 14% higher than Ref. strength.

Open Access: Yes

DOI: DOI not available

Effects of Wheel Surface Defects on Ground Borne Vibration

Szabolcs Fischer Farshad Astaraki M. Movahedi Rad Milad Kazemian Milad Akbarivarmaziar Ahmad Mohammadi Doost

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2022-01-01

Volume: 19

Issue: 6

Page Range: 129-141

Description:

Wheel ground borne vibrations, may have a significant impact on human activity and on nearby buildings. In metropolitan cities, metro lines and their development may cause such vibrations. Despite many works and solutions for path and receiver, the excitation source could also have a great effect. Wheel and rail damages are the two sources of vibration which can increase the damage impact by a factor of 5x. Wheel damage would increase dynamic vertical force noticeably and an increase in ground-borne vibration is expected. In this study with the help of finite element modelling, wheel damage including wheel flat, spalling and wheel oval is studied for a slab track and results are discussed. The studied parameters are velocity and wheel damage and their effect on ground-borne vibrations are examined.

Open Access: Yes

DOI: DOI not available

Rail Defect Classification with Deep Learning Method

Guoqing Jing Weile Qiang M. Movahedi Rad Jingru Wang Shiyao Lu

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2022-01-01

Volume: 19

Issue: 6

Page Range: 225-241

Description:

The good condition of railway rails is crucial to ensuring the safe operation of the railway network. At present, the rail flaw detectors are widely used in rail flaw detection, they are typically based on the principle of ultrasonic detection. However, the rail detection results analysis process involves huge manual work and the associated labor costs, with low levels of efficiency. In order to improve the efficiency, accuracy of results analysis and also reduce the labor costs, it is necessary to employ classification of ultrasonic flaw detection B-scan image, based on an artificial intelligence algorithm. Inspired by transformer models, with excellent performance in the field of natural language processing (NLP), some deep learning models differ from traditional convolutional neural networks (CNN), gradually emerge in the field of computer image processing. In order to explore the practicality of this model in the field of computer image processing (vision), in the paper, the Vision Transformer (ViT) is employed to train with rail defect B-scan images data and produce a rail defect classification. The model accuracy is more than 90% with the highest accuracy reaching 98.92%.

Open Access: Yes

DOI: DOI not available

Effect of Geocell, on the Mechanical Behavior of Railway Embankments, Using FE Modeling

Morteza Esmaeili Guoqing Jing Guixian Liu Farshad Astaraki M. Movahedi Rad Reza Esfandiari Mehni

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2022-01-01

Volume: 19

Issue: 6

Page Range: 63-80

Description:

In nature, the mechanical properties of soils, vary from region to region and in some areas, high-strength soil resources lack is a serious difficulty that geotechnical engineers may face where constructing earthworks such as railway and road embankments is required. Although a wide range of soil improvement techniques exists to improve such soils, the effect of geocell, as an effective solution, has not yet been investigated for railway embankments, hence, the present study aims to develop a three-dimensional (3D) Finite Element (FE) model, to fill the gap. To do this, first, six, 1/20 scaled-down railway embankments, including an unreinforced and 5 reinforced ones, were constructed in the lab and their load-settlement behavior, was assessed. Second, a 3D FE model was validated by experimental results and then, using a parametric study, the effect of geocell opening size and geocell layers number, were investigated on bearing capacity and settlement of the embankments, for five various types of soil ranging from poor soils (ST1), to high strength soils (ST5). The outcomes indicated, although adding geocell layers up to 15 layers, results in reducing the exerted stress in railway embankments by a maximum of near 50%, the crest settlement is not efficiently affected. Moreover, it was found that geocell’s opening size has a negligible effect on decreasing the embankment’s settlement, while it affects the bearing capacity significantly, up to a maximum of 50%.

Open Access: Yes

DOI: DOI not available

Optimization of the Angled Guide Plate for the Vossloh W14-PK Fastener

Guoqing Jing Yunyun Tong Peyman Aela M. Movahedi Rad Wei Qi

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2022-01-01

Volume: 19

Issue: 6

Page Range: 163-182

Description:

Angled guide plates are used to transmit the forces induced by trains, from the rail seat, to the concrete sleepers. Additionally, the design of the angled guide plates, with an appropriate width, supports tilting protection. Considering the updated requirements of the ML-1 railway line, in the Islamic Republic of Pakistan, an optimization design of the angled guide plate of the Vossloh W14-PK fasteners was carried out herein. The design requirements of the angled guide plate need to meet the requirements of structural stress and protect the plates from deterioration. Given the conducted refined model of the Vossloh W14-PK fastener, it is shown that the force and deformation of the angled guide plate, in the bearing groove adjacent and the outside bolt hole area, are small. Therefore, it was preliminarily recommended that the optimization area of the angled guide plate be divided into the section I, close to the rail groove and section II, outside the bolt hole. The Finite Element Model (FEM) of angled guide plate was established, which is used to analyze the influences of length, width, depth and the number of holes, in section I and section II, on the force distribution, across the angled guide plate. The results show that the scheme of reducing the amount of material and minimizing the influence of force on the structure of the angled guide plate, is to punch three holes in section I and two holes in section II. The holes in section I/II are 20/30 mm in length, 8/8 in width, and 15/8 mm in depth, respectively. The fatigue test showed that the optimized angled guide plate, had good application effects.

Open Access: Yes

DOI: 10.12700/APH.19.6.2022.6.12

Elasto-Plastic limit analysis of reliability based geometrically nonlinear bi-directional evolutionary topology optimization

János Lógó M. Movahedi Rad Muayad Habashneh

Publication Name: Structures

Publication Date: 2021-12-01

Volume: 34

Issue: Unknown

Page Range: 1720-1733

Description:

This paper presents elasto-plastic limit analysis of reliability-based geometrically nonlinear topology optimization. For this purpose, by reason of uncertainties the volume fraction is considered randomly during optimization. Thus reliability-based design has been considered for solving the problems. To perform reliability-based topology optimization design, the Monte-Carlo simulation method has been applied to calculate the probability of failure, thus the reliability index. Besides, bi-directional evolutionary structural optimization (BESO) method is used to consider the effect of geometrically nonlinear design for elasto-plastic analysis. Plastic behavior is controlled by applying a bound on the plastic limit load multipliers using limit analysis. The adequacy of the proposed method is exhibited by three 2D benchmark problems. 2D models of L-shape beam and U-shaped plate are considered for reliability-based design and geometrically nonlinear analysis topology optimization in case of elastic material. Additionally, 2D and 3D elasto-plastic material models have been considered to demonstrate that the proposed method can find the optimal topology of elasto-plastic models for reliability-based design and geometrically nonlinear analysis.

Open Access: Yes

DOI: 10.1016/j.istruc.2021.08.105

Laboratory Investigation on the Effect of Microsilica Additive on the Mechanical Behavior of Deep Soil Mixing Columns in Saline Dry Sand

Morteza Esmaeili Farshad Astaraki M. Movahedi Rad Hamed Yaghouti

Publication Name: Periodica Polytechnica Civil Engineering

Publication Date: 2021-11-02

Volume: 65

Issue: 4

Page Range: 1080-1091

Description:

Since loose and salty subgrades consider as problematic barriers while constructing new transportation infrastructures such as railway tracks and roads are required, the current study aims to find a solution to stabilize these kinds of subgrades using the deep soil mixing (DSM) technique and micro silica additive. In the present study a series of experimental DSM columns were executed in a salty sand-filled chamber utilizing a laboratory scale DSM apparatuses. In the first step, by adding three salt percentages of 5, 10 and 20 into the original sand, four different sandy subgrades with a relative density of 70% were prepared. Considering three percentages of 10, 15 and 20 for micro silica additive, the water-to-cement ratio of 1, salt percentages of 0, 5, 10 and 20 totally 150 sand-cement columns were constructed in the lab environment. In continuation, unconfined compression strength (UCS) and elasticity modulus of all capped DSM columns have been determined and interpreted using scanning electron microscope (SEM) images at three ages of 7,14 and 28 days. The results indicated that increasing the salinity of subgrade soil from 0 to 20% resulted in a falling UCS and Young module by 28 and 21% for 28-days specimens. Furthermore, as a solution, adding micro silica in cement-water grout up to 15% resulted in enhancing mechanical characteristics of the DSM columns. So that adding 15% microsilica caused a 21 and 42% increase in UCS and elasticity modulus of 28-days samples respectively, executed in subgrade with 20% salt.

Open Access: Yes

DOI: 10.3311/PPci.18126

Dem modeling of crushable grain material under different loading conditions

M. Movahedi Rad M. Amine Benmebarek

Publication Name: Periodica Polytechnica Civil Engineering

Publication Date: 2021-07-13

Volume: 65

Issue: 3

Page Range: 935-945

Description:

This paper deals with the effect of contact conditions on the crushing mechanisms and the strength of granular materials. The computation of crushable grain material under different loading conditions is performed using 3D model of discrete element method (DEM). The crushable macro-grain is generated from a large number of identical spherical micro-grains which are connected according to the bonded particle model. First, the parameters of the proposed DEM model are calibrated to match the force-displacement curve obtained from Brazilian Tests performed on cylinders made of artificially crushable material. The damage profile right at the point when the force-displacement curve reaches its maximum is seen to replicate the same crack patterns observed in Brazilian test experiments. Then, parametric investigations are performed by varying the coordination number, the contact location distribution, and the contact area. The results show that these parameters play a significant role in determining the critical contact force and fracture mechanism of crushable particles compared to a traditional macro-grain crushing test. Increasing distribution and coordination number of the macro-grain increases particle strength when large area contact is permitted. However, for linear contact area, the effect of increasing coordination number on particle strength is marginal.

Open Access: Yes

DOI: 10.3311/PPci.17948

Optimal plastic analysis and design of pile foundations under reliable conditions

M. Movahedi Rad Sarah Khaleel Ibrahim

Publication Name: Periodica Polytechnica Civil Engineering

Publication Date: 2021-07-13

Volume: 65

Issue: 3

Page Range: 761-767

Description:

In this research, in order to evaluate the plastic limit load and also plastic design parameters of the long pile foundations subjected to horizontal loads, shakedown method is applied. In carrying out shakedown analysis and design methods, large plastic deformations and residual displacements could develop in the pile foundation which might lead to the failure of the structure. For this reason, complementary strain energy of residual forces proposed as a limit condition to control the plastic deformation of the pile structure. Furthermore, considering the uncertainties (strength, manufacturing, geometry) the limit conditions on the complementary strain energy of residual forces are assumed randomly and the reliability condition was formed by the use of the strict reliability index. The influence of the limit conditions on the plastic limit load and design parameters of the long pile in cohesionless soil subjected to lateral load were investigated and limit curves for shakedown load factors are presented. The numerical results show that the probabilistic given limit conditions on the complementary strain energy of residual forces have significant influence on the load bearing limit and the design parameters of pile foundations. The formulations of the reliability based problems lead to mathematical programming which were carried out by the use of non-linear algorithm.

Open Access: Yes

DOI: 10.3311/PPci.17402

Condition monitoring of vibration at weak parts of rail for ballasted railway tracks in Iran

Farshad Astaraki M. Movahedi Rad Ali Taheri Milad Kazemian

Publication Name: Journal of the Korean Society for Railway

Publication Date: 2021-06-01

Volume: 24

Issue: 6

Page Range: 544-551

Description:

Vibration monitoring has become important in railway tracks for many purposes. One of the most important purposes is to prevent exceeding limits of induced vibration to adjacent residential buildings. In the current study, to measure the level of vibration, a field investigation is carried at three critical positions including a curve, a fishplate and a deflected rail weld. The field study is an old ballasted railway track located at the critical /one of the entrance of Mashhad Railway station in Iran. In this regard, three distinct field tests are performed using accelerometer sensors and the obtained data arc analyzed and assessed. Besides this, vibrations at 5 and 10 m-distancc from the track arc also considered and rccordcd. As the main achievement, results show that induced vibration levels arc highly dependent on the condition of contact surface between wheel and rail

Open Access: Yes

DOI: 10.7782/JKSR.2021.24.6.544

Numerical study on the micro-mechanical behaviour of artificial granular materials

M. Movahedi Rad M. Amine Benmebarek

Publication Name: Fib Symposium

Publication Date: 2020-01-01

Volume: Unknown

Issue: Unknown

Page Range: 86-93

Description:

Numerical models for the simulation of the micro-mechanical behaviour of granular assemblies have a wide range of applications, for instance in material science, process engineering, environmental engineering, railway engineering and geotechnical engineering (in this study we examined one macro-grain but what important is behaviour of granular assemblies). In this examination, experimental tests and numerical computations using the discrete element method (DEM) are carried out to evaluate the micro-mechanical behviour of the granular materials. For this purpose, artificial materials are taken into consideration for experimental Brazilian laboratory tests, and then according to the experimental results the DEM model is calibrated. Artificial crushable materials are produced by mixing cement and silt according to their mass ratio, in which cement can provide bonding and silt is the main filling material. In the DEM model, a 3D crushable granular material ‘macro-grain’ is built up from a large number of micro-grains which are associated according to crushable parallel bond properties. The behaviour of the single crushable grains and the fragmentation patterns under different contact configuration and load position are studied. The DEM simulation results show that the contact configuration type and load position affect the fragmentation patterns and loading capacity.

Open Access: Yes

DOI: DOI not available

Numerical plastic analysis of non-prismatic reinforced concrete beams strengthened by carbon fiber reinforced polymers

M. Movahedi Rad Sarah Khaleel Ibrahim

Publication Name: Proceedings of the 2020 Session of the 13th Fib International Phd Symposium in Civil Engineering

Publication Date: 2020-01-01

Volume: Unknown

Issue: Unknown

Page Range: 208-215

Description:

The non-prismatic reinforced concrete (RC) beam considered a unique case in structural engineering as it has variable depth all over beam section and it doesn't have sufficient information in structural codes, this can put structural engineers in a challenge to predict how this beam will react under specific types of loads or with different geometrical variables and strengthening existence. In this research, concrete plastic damage constitutive model developed and used to explore the shear strength of non-prismatic RC beam structure. Furthermore, in order to improve the shear strength of existent RC beams, Carbon Fiber Reinforced Polymers (CFRP) strips are attached to the surface of the critical sections. For this aim, initially numerical model was calibrated according to the data obtained from laboratory tests then a series of numerical simulations with different variables are carried out to investigate the shear behavior and these variables were: haunch angle a value and CFRP strips existence (composite status). The numerical results show that changing beams geometry (haunch angle a value) can have an influence over shear strength, in addition, using CFRP strips has an obvious effect on the failure behavior of the non-prismatic RC beam structure. Finite element simulations are executed by using ABAQUS.

Open Access: Yes

DOI: DOI not available

Numerical plastic analysis of non-prismatic reinforced concrete beams strengthened by carbon fiber reinforced polymers

M. Movahedi Rad Sarah Khaleel Ibrahim

Publication Name: Fib Symposium

Publication Date: 2020-01-01

Volume: Unknown

Issue: Unknown

Page Range: 208-215

Description:

The non-prismatic reinforced concrete (RC) beam considered a unique case in structural engineering as it has variable depth all over beam section and it doesn’t have sufficient information in structural codes, this can put structural engineers in a challenge to predict how this beam will react under specific types of loads or with different geometrical variables and strengthening existence. In this research, concrete plastic damage constitutive model developed and used to explore the shear strength of non-prismatic RC beam structure. Furthermore, in order to improve the shear strength of existent RC beams, Carbon Fiber Reinforced Polymers (CFRP) strips are attached to the surface of the critical sections. For this aim, initially numerical model was calibrated according to the data obtained from laboratory tests then a series of numerical simulations with different variables are carried out to investigate the shear behavior and these variables were: haunch angle α value and CFRP strips existence (composite status). The numerical results show that changing beams geometry (haunch angle α value) can have an influence over shear strength, in addition, using CFRP strips has an obvious effect on the failure behavior of the non-prismatic RC beam structure. Finite element simulations are executed by using ABAQUS.

Open Access: Yes

DOI: DOI not available

Numerical study on the micro-mechanical behaviour of artificial granular materials

M. Movahedi Rad M. Amine Benmebarek

Publication Name: Proceedings of the 2020 Session of the 13th Fib International Phd Symposium in Civil Engineering

Publication Date: 2020-01-01

Volume: Unknown

Issue: Unknown

Page Range: 86-93

Description:

Numerical models for the simulation of the micro-mechanical behaviour of granular assemblies have a wide range of applications, for instance in material science, process engineering, environmental engineering, railway engineering and geotechnical engineering (in this study we examined one macro-grain but what important is behaviour of granular assemblies). In this examination, experimental tests and numerical computations using the discrete element method (DEM) are carried out to evaluate the micro-mechanical behviour of the granular materials. For this purpose, artificial materials are taken into consideration for experimental Brazilian laboratory tests, and then according to the experimental results the DEM model is calibrated. Artificial crushable materials are produced by mixing cement and silt according to their mass ratio, in which cement can provide bonding and silt is the main filling material. In the DEM model, a 3D crushable granular material 'macro-grain' is built up from a large number of micro-grains which are associated according to crushable parallel bond properties. The behaviour of the single crushable grains and the fragmentation patterns under different contact configuration and load position are studied. The DEM simulation results show that the contact configuration type and load position affect the fragmentation patterns and loading capacity.

Open Access: Yes

DOI: DOI not available

Influence of the loading condition on single grain crushing in DEM simulation

Saeed Safikhani M. Movahedi Rad Erich Bauer

Publication Name: Periodica Polytechnica Civil Engineering

Publication Date: 2019-12-18

Volume: 63

Issue: 4

Page Range: 1152-1158

Description:

Grain crushing is of essential importance for understanding the mechanical behavior of granular materials such as sand, gravel or broken rock under higher pressures. In order to investigate the breakage mechanism of a single grain under different loading conditions, numerical simulations are carried out using DEM. Two different types of boundary conditions are considered to apply displacement-controlled load: loading using platens and loading by uncrushable macro-grains. A 2D crushable macro-grain is built up from a large number of micro-grains which are connected with respect to breakable parallel-bond properties. The response of the crushable macro-grain for different coordination numbers and location of the contact points is discussed. The numerical results show that the type of loading condition can influence the loading capacity and fragmentation patterns of the crushable macro-grain.

Open Access: Yes

DOI: 10.3311/PPci.14541

Optimal Plastic Analysis of Structures under Uncertain Conditions

M. Movahedi Rad

Publication Name: Iop Conference Series Materials Science and Engineering

Publication Date: 2019-12-05

Volume: 686

Issue: 1

Page Range: Unknown

Description:

In this study optimum plastic shakedown analysis of framed steel structures with semi-rigid connections (SRC) between beam and columns subjected to multi-parameter static loading presented. Since shakedown analysis does not provide information concerned with the accumulated residual displacements, complementary strain energy of the residual force (CSERF) considered as constrain to evaluate the post yield behavior of framed steel structures. The constraints on the CSERF are modelled using probabilistic and deterministic methods. To evaluate the maximum shakedown load-multipliers a numerical example is introduced, shakedown load-multipliers are calculated and safe loading domains of the framed steel structure are illustrated. The numerical results show that the constraints on CSERF, SRC and probabilistic given constraints can influence on the value of the shakedown load-multipliers.

Open Access: Yes

DOI: 10.1088/1757-899X/686/1/012002

Warping transfer superelement model for bolted end-plate connections subject to 3D loads

B. Vaszilievits-Sömjén M. Movahedi Rad J. Szalai

Publication Name: Stability and Ductility of Steel Structures Proceedings of the International Colloquia on Stability and Ductility of Steel Structures 2019

Publication Date: 2019-01-01

Volume: Unknown

Issue: Unknown

Page Range: 1210-1217

Description:

A simple beam element based modelling technique has been developed which makes possible to analyze frames made of I sections with column-rafter bolted end-plate connections, subject to 3D loads, compatible with the thin walled beam theory with 7DOF beam elements. The model previously developed by the same team for welded connections has been ex-tended with the addition of linear spring elements to model the bolts located at the upper and lower beam flange level. The spring stiffnesses are calculated based on the extension of the Eurocode component method and verified by simulations performed with FEA software Abaqus.

Open Access: Yes

DOI: DOI not available

Warping transfer superelement model for bolted end-plate connections subject to 3D loads

B. Vaszilievits-Sömjén M. Movahedi Rad J. Szalai

Publication Name: Sdss 2019 International Colloquium on Stability and Ductility of Steel Structures

Publication Date: 2019-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

A simple beam element based modelling technique has been developed which makes possible to analyze frames made of I sections with column-rafter bolted end-plate connections, subject to 3D loads, compatible with the thin walled beam theory with 7DOF beam elements. The model previously developed by the same team for welded connections has been extended with the addition of linear spring elements to model the bolts located at the upper and lower beam flange level. The spring stiffnesses are calculated based on the extension of the Eurocode component method and verified by simulations performed with FEA software Abaqus.

Open Access: Yes

DOI: DOI not available

Elasto-limited plastic analysis of structures for probabilistic conditions

M. Movahedi Rad

Publication Name: Iop Conference Series Materials Science and Engineering

Publication Date: 2018-06-12

Volume: 372

Issue: 1

Page Range: Unknown

Description:

With applying plastic analysis and design methods, significant saving in material can be obtained. However, as a result of this benefit excessive plastic deformations and large residual displacements might develop, which in turn might lead to unserviceability and collapse of the structure. In this study, for deterministic problem the residual deformation of structures is limited by considering a constraint on the complementary strain energy of the residual forces. For probabilistic problem the constraint for the complementary strain energy of the residual forces is given randomly and critical stresses updated during the iteration. Limit curves are presented for the plastic limit load factors. The results show that these constraints have significant effects on the load factors. The formulations of the deterministic and probabilistic problems lead to mathematical programming which are solved by the use of nonlinear algorithm.

Open Access: Yes

DOI: 10.1088/1757-899X/372/1/012032

A review of elasto-plastic shakedown analysis with limited plastic deformations and displacements

M. Movahedi Rad

Publication Name: Periodica Polytechnica Civil Engineering

Publication Date: 2018-05-22

Volume: 62

Issue: 3

Page Range: Unknown

Description:

In classical plasticity the shakedown analysis is among the most important basic problems. The principles of shakedown analysis are counterparts to those of limit analysis in the sense that they provide static and kinematic approaches to the question of whether or not shakedown will occur for a body under multiple variable loading conditions. The principles of limit analysis provide static and kinematic approaches to the question of whether or not the plastic limit state will be reached by a body under proportional loading. The principles of shakedown analysis are, however, considerably more difficult to apply than those of limit analysis. In spite of these difficulties, shakedown analysis is a vital and developing topic in plasticity and a great number of applications have been made. At the application of the plastic analysis and design methods the control of the plastic behaviour of the structures is an important requirement. Since the shakedown analysis provide no information about the magnitude of the plastic deformations and residual displacements accumulated before the adaptation of the structure, therefore for their determination bounding theorems and approximate methods have been proposed.

Open Access: Yes

DOI: 10.3311/PPci.11696

Reliability based analysis and optimum design of laterally loaded piles

M. Movahedi Rad

Publication Name: Periodica Polytechnica Civil Engineering

Publication Date: 2017-01-01

Volume: 61

Issue: 3

Page Range: 491-497

Description:

In this study reliability based limit analysis is used to determine the ultimate capacity of laterally loaded piles. The aim of this study is to evaluate the lateral load capacity of free-head and fixed-head long pile when plastic limit analysis is considered. In addition to the plastic limit analysis to control the plastic behaviour of the structure, uncertain bound on the complementary strain energy of the residual forces is also applied. This bound has significant effect for the load parameter. The solution to reliability-based problems is based on a direct integration technique and the uncertainties are assumed to follow Gaussian distribution. The optimization procedure is governed by the reliability index calculation.

Open Access: Yes

DOI: 10.3311/PPci.8756

Plastic limit analysis of lateral piles for uncertain conditions

Z. Fehér M. Movahedi Rad

Publication Name: Civil Comp Proceedings

Publication Date: 2014-01-01

Volume: 106

Issue: Unknown

Page Range: Unknown

Description:

In the study, presented in this paper, a general approach to the reliability based limit analysis of laterally loaded piles is presented. In engineering practice uncertainties play a very important role. The aim of this study is to evaluate the lateral load capacity of a long pile when plastic limit analysis is considered. In addition to the plastic limit analysis to control the plastic behaviour of the structure, a bound on the complementary strain energy of the residual forces is also applied. This bound has a significant effect for the load parameter. The solution to reliability-based problems is obtained by a computer program which is governed by the reliability index calculation.

Open Access: Yes

DOI: DOI not available

Elasto-Plastic Analysis of Two-Way Reinforced Concrete Slabs Strengthened with Carbon Fiber Reinforced Polymer Laminates

Zahraa Saleem Sharhan M. Movahedi Rad

Publication Name: Computation

Publication Date: 2024-05-01

Volume: 12

Issue: 5

Page Range: Unknown

Description:

This study explores a technique for enhancing the punching strength of reinforced concrete (RC) flat slabs, namely carbon fiber reinforced polymer (CFRP). Four large-scale RC flat slabs were fabricated, to assess the efficacy of this strengthening method. One slab served as a reference and the three other specimens were strengthened with CFRP, as a method of external strengthening. These slabs, featuring identical overall dimensions and flexural steel reinforcement, underwent testing until failure, under the influence of concentrated patch loads. A concrete plastic damage constitutive model (CDP) was developed and employed to examine the strength of two-way RC slabs. Additionally, to enhance the strength of existing RC slabs, carbon fiber reinforced polymer (CFRP) strips are affixed to the tension surface of the sections. The research begins with the calibration of a numerical model, based on data from laboratory tests. The objective of this study is to constrain the plastic behavior of two-way RC slabs reinforced with CFRP, with a focus on establishing an optimal elasto-plastic analysis, aimed at controlling concrete damage plasticity using CFRP, and employing a plastic limit load multiplier. Subsequently, a series of numerical simulations, incorporating different variables, are conducted to investigate shear behavior. The numerical results indicate that an increase in the strengthening ratio has a significant impact on shear strength. Finite element simulations are carried out using Abaqus CAE®/2018.

Open Access: Yes

DOI: 10.3390/computation12050093

Assessment of soil erosion patterns in Maharloo watershed using remote sensing techniques and early warning signals

Hamid Reza Pourghasemi Farzaneh Fathi Narges Kariminejad Abdolhossein Boali M. Movahedi Rad Vahid Shafaie Seyed Rashid Fallah Shamsi Farzaneh Fathi

Publication Name: Journal of Arid Environments

Publication Date: 2026-02-01

Volume: 232

Issue: Unknown

Page Range: Unknown

Description:

This study assessed the soil erosion dynamics in Iran's Maharloo watershed using remote sensing indices (Normalized Difference Vegetation Index (NDVI), Normalized Difference Salinity Index (NDSI), and Topsoil Grain Size Index (TGSI)) and machine learning models (RF, SVM, and BRT). Landsat 8 satellite images (2005–2024) were processed via the Google Earth Engine, with field validation ensuring accuracy. Among the indices, TGSI (R2 = 0.86), NDSI (R2 = 0.89), and NDVI (R2 = 0.87) showed the strongest correlations with ground data (Rain, Soil and Vegetation). The RF outperformed the other models (AUC = 0.89), identifying the central and western regions as warning erosion zones. Breakpoint analysis revealed abrupt changes in NDVI and NDSI (2013), while early warning signals (autocorrelation, variance, and skewness) indicated an escalating erosion warning, particularly near wetlands and rainfed fields. Spatial trends highlighted significant NDVI declines (Kendall's τ = 0.69) in wetland peripheries and NDSI increased (τ = 0.52) in northern farmlands. These findings underscore the efficacy of integrating machine learning and remote sensing for erosion monitoring, providing actionable insights for land management and conservation strategies.

Open Access: Yes

DOI: 10.1016/j.jaridenv.2025.105496