Optimal damper placement in steel frames by the Endurance Time method

Abstract

AbstractPerformance‐based optimal seismic design of structures requires repetitive and massive dynamic analyses. In the Endurance Time (ET) method, structures are subjected to specially designed intensifying acceleration functions and their response at various excitation levels is estimated by each single response‐history analysis, thus, significantly reducing the required computational demand. In this paper, the ET method is utilized to acquire optimal placement of viscous dampers in short steel frames with the target of obtaining the desirable performance in two hazard levels simultaneously. In the optimization procedure, the damping coefficients of the added dampers are treated as design variables and assigned such that the total damping coefficients used in the structure would be minimal. Moreover, the performance of the structures before and after damper placement has been evaluated using ground motions. The sensitivity of the results to the selection of a particular set of ground motions is also investigated. Nonlinear models of steel frames have been investigated and the optimization procedures are conducted with genetic algorithm. Recommendations of ASCE/SEI 41‐06 code are followed in setting the performance design criteria. Copyright © 2011 John Wiley & Sons, Ltd.