Reliability-based layout optimization of concentrically braced in 3D steel frames

Abstract

For an economical and safe design of building systems with concentrically braced frames, the layout of the braces should be done by considering all limitations. The current study proposes an approach for a reliability-based optimal design of concentric bracing layouts in 3D steel frames. The objective function was considered to be a reduction in the total weight. The layout of the braces was considered as the variable of the optimization problem. The deterministic design constraints of limitations of strength, drift and torsional irregularities were considered according to AISC 360-16 and ASCE 7-16. The distance between the center of mass and the center of rigidity was defined as the probability constraint. The probabilistic variables were the intensity of the distributed loads and the cross-sectional area of the braces and columns. The reliability index was evaluated using the Monte Carlo simulation method. The reliability-based design optimization (RBDO) problem was solved for 4-, 5- and 9-story steel space frames using the EVPS algorithm. To investigate the effect of the probabilistic constraint on the optimal design, numerical examples were solved without applying this constraint and the solutions to the RBDO and deterministic design optimization problems were compared.