The aim of this paper is to show that the fuzzy signature model based on non-destructive in-situ measurements and visual inspection can be used to obtain equally reliable results on the strength of masonry as destructive tests. The fuzzy signature model was constructed to describe a masonry based on different measurements of. The aggregations of the signature were given as weighted geometric means. Weights of the input values of the aggregations were determined by two different optimization methods: (i) an iteration procedure was chosen, which showed significant differences in the result; (ii) a genetic algorithm was used, which produced similar but more accurate approximations to the results of the destructive tests. The comparison of the two optimization results gave new conclusions that are valuable information for the further development.

Fuzzy signatures have been successfully used for various engineering applications including the strength and condition assessment of structural materials. In this paper, fuzzy signatures were used to determine the compressive strength of masonry based on groups of related measured values. Handling the uncertainty this way seemed useful because of the subjective parts and influencing noise factors of the measurements which are incorporated as leaves in the signature. For such modeling the structure from where the algebraic framework can be obtained which allows making computations with the fuzzy signatures thus determined. Since multiplicative type aggregations are applied on the various material test results assigned to the leaves of the signatures for the determination of the compressive strength of masonry, fuzzy arithmetic multiplication based on Zadeh’s extension principle was applied here. To perform the fuzzy signature calculations, the scalar product and the n-th root of fuzzy numbers were used.