Participation Ratio of Frames in Design Base Shear of Dual Shear Wall-Frames Systems According to Optimal Design of the Seismic Resistant R\C Buildings

Abstract

Dual shear walls-frames system is considered one of the most efficient sytems to resist earthquake in high-rise buildings. Design codes dictates that

a minimum of 25% of design base shear forces should be resisted by frames part only without giving a specific ratio. In this research an optimization algorithm that applies cost as an objective function, has been used to optimally design the structure of high rise buildings. That is to reach the minimum cost required with all design constraints fulfilled. After that the participation ratio of the frame part can be calculated. For this purpose an algorithm named after Nelder-Mead that applies simplex method was used in conjunction with Abaqus software to search for the least cost design. Abaqus’s models were analyzed during optimization process for hundred of times through time-history nonlinear dynamic analysis under base excitation that applies design earthquake acceleration records. The parametric model built on Abaqus was interconnected with the algorithm to be analyzed several hundred of times reaching the optimum design of this model. After processing three models in the same manner, one with central core and excitation about the weak direction of the model. And two with full symmetry about x and y axis. The results concluded that there is no specific ratio or range that result in cost effective dual system. But rather the participation ratio might change significantly with a minimum replacement of the shear walls in plan.