Comparação de custos de lajes lisas submetidas à flexão e à punção com utilização de algoritmos de otimização

Abstract

The objective of this paper was to analyze and compare costs of flat slab designs, presented as a function of the materials steel and concrete, considering the punching effect. Two cases of flat slabs supported on corner columns were developed using optimization, whose algorithms perform the analysis of the efforts and the design of the flexural reinforcement and punching, where the objective functions are constituted by the steel rate and the concrete volume. The linear and non-linear constraints are represented by equations for bending moment design, shear stress analysis, and punching design, as prescribed by NBR 6118:2014. The effective depth was considered as a design variable in both cases, and in the second case the number of shear reinforcement lines, stud bolt type in a radial distribution, and the number of studs per line are also design variables. In the first case, a restriction was imposed regarding the slab thickness so that there was no need for punching shear reinforcement, while in the second case the possibility of punching shear reinforcement was considered, whose weight was also implemented in the objective function. In order to compare the results of the two cases, examples with different values for concrete compressive strength were analyzed, which were validated with results available in the literature.