Seismic performance of post-tensioned self-centering concrete frames under near-fault pulse-like ground motions

Abstract

Post-tensioned self-centering (PTSC) frames have been identified as a class of high-performance structures with capabilities of mitigating damage and minimizing residual deformations. However, the seismic behavior of PTSC frames subjected to near-fault pulse-like ground motions (NPGMs) is not fully understood yet. This study provides a comprehensive assessment on the seismic performance of PTSC frames under NPGMs. 4-story and 12-story PTSC frames with different energy dissipation capacities are numerically modeled in the OpenSees platform. Various degrees of structural damage of the PTSC frames are properly described by particular limit states. Incremental dynamic analysis (IDA) is performed using a set of 91 near-fault ground motions with a wide range of pulse periods. Fragility surfaces for different damage states are developed for the exemplar PTSC frames with respect to both seismic intensity and pulse period. The numerical results indicate that the impacts of pulse period on the PTSC frames of different stories are quite different. Besides, the most unfavorable pulse period changes with the severity of structural damage. The effects of energy dissipation ratio and pulse period on the exceedance probabilities of different damage states are compared, and the limitation of the commonly adopted friction dampers is discussed. Based on the results and observations of structural performance with respect to the pulse characteristics, guides and recommendations for the design of PTSC frames are provided.