Two-stage equal reliability optimization for mega-sub controlled structure system with lead rubber bearings

The Mega-Sub Controlled Structure Systems (MSCSS) with lead rubber bearings (LRBs) is an innovative and attractive vibration control system. This study proposes a method for obtaining the optimal member sizes of the MSCSS with LRBs under non-stationary stochastic ground motions. Based on the structural characteristics of the MSCSS with LRBs, this study puts forward the "optimal criteria method with two-stage equal reliability." The probability density evolution theory is used for the dynamic reliability analysis of the MSCSS with LRBs, and a MATLAB program is written for the member size optimization. A finite element model with four mega-floors and 32 sub-floors is studied as an example. The reliability and seismic response of the model before and after optimization are compared. The optimization eliminates the "weak floors" in the structure so that the reliability distribution after optimization is more uniform than before, and the seismic performance of the structure is also improved.