Algoritmos de otimização aplicados na avaliação da confiabilidade estrutural de vigas em concreto armado submetidas à flexão simples

Abstract

Structural reliability analysis has a fundamental role in the safety assessment of a structure, being mentioned in the literature as the most rational way to designing, especially in Brazil, since there is little information related to the reliability of structures designed based on national standards. Due to its conventional formulation, the structural reliability makes possible to consider the uncertainties inherent to the various parameters in order to obtain the probability of failure, which can be determined by solving a restricted optimization problem. In this context, na algorithm widely used to solve this problem is the HLRF, however, there are situations in which it may not converge. Therefore, the objective of this work was to compare the performance of HLRF, iHLRF, nHLRF and HLRF-BFGS algorithms, in the evaluation of the structural reliability of reinforced concrete beams submitted to simple bending and dimensioned according to the specifications established by ABNT NBR 6118:2014. The fact that the nHLRF and HLFR-BFGS algorithms have not yet been applied to any real practical problem, such as the one proposed here, it was an additional motivation for carrying out this research. Therefore, numerical experiments were carried out in order to investigate the performance of the algorithms and, also, to analyze the influence of the variables, established in the design, on the value of the failure probability of the beams. The results indicated that the HLRF-BFGS algorithm is more robust than the other algorithms and, in addition, the loading rate has a relevant influence on the probability of failure of the structure.