An efficient approach for LCC-based optimum design of lead-rubber base isolation system via FFD and analysis of variance (ANOVA)

Abstract

A framework for optimal design of lead rubber bearing (LRB) system is introduced based on the initial and life cycle cost of structures. The purpose of this framework is to minimize the initial and life cycle cost of building and simultaneously improve the seismic performance of the base isolated structure. Endurance time (ET) method is used to predict the seismic response of the building at continuous levels of hazard intensity. Before implementing the optimization process, a full factorial design is utilized, and the seismic performance of a total of 128 lead rubber base isolated structures with varying LRB design parameters is assessed using the ET analysis method. Accordingly, the parameters with the most significant impact on the responses are determined by the analysis of variance. These parameters are used as design variables in a multi-objective genetic algorithm to minimize the initial and life cycle cost of the building with LRB system. The cost analysis of the system requires evaluation of initial costs including the costs associated with the implementation of LRBs. To date, no appropriate cost model has been proposed for LRB systems in the literature; therefore, a simplified cost model for LRBs is developed. Also, a life cycle cost model is used to evaluate the structural performance in the form of economic measures based on the results obtained from the ET analysis. In order to illustrate the method, a prototype six-story building is studied here. According to the results, the proposed approach is found to be effective in reducing the initial and life cycle cost of the building with an acceptable amount of computational effort.