Seismic retrofit of RC buildings using self-centering PC frames with friction-dampers

Abstract

This paper presents the seismic upgrade of existing reinforced concrete (RC) structures by using a self-centering post-tensioned pre-cast concrete frame with friction dampers (SC-PC-FD). The effectiveness of the retrofit is investigated through conducting cyclic loading tests on a single story RC frame before and after the retrofit. The experimental results are used to validate the numerical modeling of the test specimens. A performance-based seismic design procedure is proposed based on a genetic algorithm (GA) to determine the story-wise distribution of the damper friction capacity and the area of post-tensioning steel. Three-, five-, and eight-story RC framed structures are used as case study models for evaluating the effectiveness of the retrofit technique. Non-linear time-history response analysis (NLTHA), incremental dynamic analysis (IDA), and fragility analysis are conducted to investigate the seismic performance of the retrofitted structures. Results of the nonlinear time-history analyses show that the retrofit reduces the maximum inter-story drift ratio (MIDR) and the residual drift of the model structures. IDA and fragility curves show that the collapse capacities of the model structures are increased after the retrofit and the retrofitted buildings have lower probabilities of reaching the design limit states compared to the un-retrofitted ones.