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Stabilization of Expansive Soils Using Mechanical and Chemical Methods: A Comprehensive Review

Elizabeth Theron Armand Augustin Fondjo R. P. Ray

Publication Name: Civil Engineering and Architecture

Publication Date: 2021-08-01

Volume: 9

Issue: 5

Page Range: 1289-1294

Description:

The presence of expansive soils on construction sites is problematic in geotechnical engineering. The swell-shrink behaviour makes these soils not suitable to be used in their natural state. The expansive soil damages cause financial loss yearly more than floods, hurricanes, tornadoes, and earthquakes combined. Moreover, the cost of cut to spoil of expansive soils during construction projects has continued to rise because of the high cost of earthworks, haulage, and the increasing scarcity of spoil areas because of the built environment. Nonetheless, a proper stabilization technique can significantly enhance the expansive soil's properties. The research project attempts to review, report the limits and merits of mechanical and chemical methods utilized to stabilize expansive soils in line with their efficiency, environmental concerns, and cost-effectiveness. A review of mechanical and chemical treatment techniques is conducted in this regard. Ultimately, each stabilization method exhibits its merits and limitations. The lack of standards for the treatment of swelling soils is a significant problem in engineering practice. Specialists in the domain of soil treatment must work together to obtain an optimized stabilization approach and protocol. Moreover, engineers should perform a geoenvironmental assessment appropriate for chemical stabilization methods and additives utilized. This research work contributes as a guideline in the selection and application of chemical and mechanical stabilization methods.

Open Access: Yes

DOI: 10.13189/cea.2021.090503

Eigenshape based imperfection method for beam-columns with mono-symmetric I-sections

Achim Rubert G. Hajdú

Publication Name: Stahlbau

Publication Date: 2021-08-01

Volume: 90

Issue: 8

Page Range: 600-613

Description:

Eigenshape based imperfection method for beam-columns with mono-symmetric I-sections. This paper shows for the first time the application of the Overall Imperfection Method (OIM) for columns, beams and beam-columns with mono-symmetric I cross-section. The buckling failure mode of compressed members with mono-symmetric I-section is torsional-flexural like. The second-order effect from the rotation around the longitudinal shear axis during the loss of stability is taken into account when the amplitude of the initial imperfection is calculated for the compressed members. For beams, the buckling behaviour is also different from doubly symmetric cross-section because the shear centre and the centre of gravity of the cross-section do not meet at the same position. This paper shows the extension and the usability of the OIM for steel structures with mono-symmetric I-section. The automatic determination of the equivalent amplitudes for columns, beams and beam-columns are presented for the first time. The practicality of the proposed method is demonstrated for single and multi-span members with three examples.

Open Access: Yes

DOI: 10.1002/stab.202100017

Cartel cases: From state negligence to direct political interest in Hungary

Tamás Bezsenyi Éva Inzelt

Publication Name: European White Collar Crime Exploring the Nature of European Realities

Publication Date: 2021-07-21

Volume: Unknown

Issue: Unknown

Page Range: 187-204

Description:

No description provided

Open Access: Yes

DOI: DOI not available

Numerical investigation on flexural buckling behavior of hot-rolled steel columns at elevated temperatures

Samer Nemer F. Papp

Publication Name: Periodica Polytechnica Civil Engineering

Publication Date: 2021-07-13

Volume: 65

Issue: 3

Page Range: 918-927

Description:

In this paper, a numerical investigation on the global buckling capacity of the axially compressed steel columns with hot-rolled I cross-section at elevated temperatures is presented. Geometrically and materially non-linear finite element model and the ABAQUS software were used to determine the buckling resistance. The numerical ABAQUS model was validated using experimental results available in the literature, and then the validated numerical model was used to generate a database of load-carrying capacity. The parametric study covered three different cross-section classes (class 1, 2 and 3), ten different non-dimensional slenderness ̄λ = 0.5, 0.6, 0.7, 0.9, 1.1, 1.3, 1.5, 1.7, 1.9, 2.0), three different temperatures (400°C, 500°C, 600°C), and two stress-strain constitutive relations including (the nonlinear material model adopted in the European guidance for structural fire design EN1993-1-2, and a Bilinear material model), with and without residual stress. The influence of the model parameters on the load capacity of steel columns at elevated temperatures was evaluated. The results of the parametric study were compared with the results of the simplified calculation model presented in EN1993-1-2.

Open Access: Yes

DOI: 10.3311/PPci.17799

Dem modeling of crushable grain material under different loading conditions

Majid 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

Measurement distortion analysis of repetitive and isolated track geometry irregularities

Csaba Ágh

Publication Name: Periodica Polytechnica Civil Engineering

Publication Date: 2021-07-13

Volume: 65

Issue: 3

Page Range: 852-865

Description:

Track geometry measurements are essential for day-to-day activities of railway maintenance and play an important role in vehicle-track simulations. The generally applied forms of longitudinal level and alignment recordings do not reflect the real shape of the track. Both the versine measurement method and the band-pass filters according to European regulation cause significant amplitude modification and pattern change. In addition, the distortion behavior of repetitive and isolated defects is fundamentally different. In this contribution, simulated measurements of various reference shapes, which represent repetitive and isolated track deformations, were investigated. Comprehensive functions for amplitude change and for other distortion factors were developed with analytical and numerical methods. For chord measurements, rules were found for zero points and distortion-free ranges. Regarding the standardized filters, a significant amplitude reduction of isolated defects was observed in all wavelength ranges. Since derailment and track degradation depend not only on the amplitude of the defect, also the derivatives of the original and filtered forms of reference shapes were investigated and, as a new approach, the defect features called 'hypothetical additional force', 'speed of hypothetical wheel lift-off', 'hypothetical deterioration impulse' and 'hypothetical deterioration energy' were introduced.

Open Access: Yes

DOI: 10.3311/PPci.17638

Optimal plastic analysis and design of pile foundations under reliable conditions

Majid 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

A Canonical Set of Operations for Editing Dashboard Layouts in Virtual Reality

Adam B. Csapo Tarek Setti

Publication Name: Frontiers in Computer Science

Publication Date: 2021-07-12

Volume: 3

Issue: Unknown

Page Range: Unknown

Description:

Virtual reality (VR) is a powerful technological framework that can be considered as comprising any kind of device that allows for 3D environments to be simulated and interacted with via a digital interface. Depending on the specific technologies used, VR can allow users to experience a virtual world through their different senses, i.e., most often sight, but also through touch, hearing, and smell. In this paper, it is argued that a key impediment to the widespread adoption of VR technology today is the lack of interoperability between users’’ existing digital life (including 2D documents, videos, the Web, and even mobile applications) and the 3D spaces. Without such interoperability, 3D spaces offered by current VR platforms seem empty and lacking in functionality. In order to improve this situation, it is suggested that users could benefit from being able to create dashboard layouts (comprising 2D displays) for themselves in the 3D spaces, allowing them to arrange, view and interact with their existing 2D content alongside the 3D objects. Therefore, the objective of this research is to help users organize and arrange 2D content in 3D spaces depending on their needs. To this end, following a discussion on why this is a challenging problem—both from a scientific and from a practical perspective—a set of operations are proposed that are meant to be minimal and canonical and enable the creation of dashboard layouts in 3D. Based on a reference implementation on the MaxWhere VR platform, a set of experiments were carried out to measure how much time users needed to recreate existing layouts inside an empty version of the corresponding 3D spaces, and the precision with which they could do so. Results showed that users were able to carry out this task, on average, at a rate of less than 45 s per 2D display at an acceptably high precision.

Open Access: Yes

DOI: 10.3389/fcomp.2021.659600

Interpolative decisions in the fuzzy signature based image classification for liver CT

Ferenc Lilik Melinda Kovacs Szonja Krisztina Szujo Ĺaszĺo T. Ḱoczy Szilvia Nagy

Publication Name: IEEE International Conference on Fuzzy Systems

Publication Date: 2021-07-11

Volume: 2021-July

Issue: Unknown

Page Range: Unknown

Description:

In computer aided diagnostics image processing and classification plays an essential role. Image processing experts have been developing solutions for different types of problems, that can be related to image processing, however, due to the sensitivity of the data and the high cost of medical experts, these experimental methods usually have very limited use in real medical practice. The databases that are available are very limited, thus the elsewhere usual and extremely effective convolutional neural network or other automated learning methods are not so easy to adjust for medical image processing. To overcome this difficulty, this paper presents an expert knowledge based method which describes the decision structures by fuzzy signatures. Values of various properties of Computer Tomography images as e.g. density or homogeneity are being considered in these signatures that are different in all case of liver diseases. Because of the low number of samples available, fuzzy sets that describes the leafs of the signatures leads to sparse systems, hence interpolation is needed. However further investigations of other interpolation methods are planned, Stabilized Koczy-Hirota interpolation seems to be appropriate.

Open Access: Yes

DOI: 10.1109/FUZZ45933.2021.9494401