Size and topology optimization of truss-like structures under seismic excitations incorporating probabilistic aspects

The present research develops a practical method for size and topology optimization of nonlinear truss-like structures against earthquake effects by incorporating strong ground motion uncertainties. For optimum design solutions, an adaptive optimization technique is adopted. The cross-sectional area of structural members is modified based on the structure's nonlinear time history response until a uniform distribution of Mean Annual Frequency of Exceedance (MAFE) of member ductility is achieved. Three truss-like structures are optimized against a set of 11 strong ground motions to demonstrate the efficiency and accuracy of the proposed method. The effects of target MAFE in member ductility, target ductility value, convergence parameter (i.e., β values), and initial cross-sectional area of members on the optimum topology are investigated. To study the effects of ground motion uncertainties, the MAFE values of the optimum design structures are obtained against a new set of 50 strong ground motions. The results generally confirm the adequacy and reliability of the proposed optimization method by leading to acceptable MAFE of member ductility values close to the predefined target.