Self-centering steel slotted friction device for seismic retrofit of beam-column joints

Abstract

A new self-centering slotted friction device (SC-SFD) is introduced for seismic retrofit and upgrading of beam-column joints. The device can be used for existing or new structures. A framework utilizing a performance-based seismic design procedure combined with a genetic algorithm (GA) optimization is used to obtain the optimum design variables of the device. A 5-story building and one-story industrial structure are used as case studies. The effectiveness of the proposed retrofit is assessed through conducting non-linear time-history response analysis (NLTHA), incremental dynamic analysis (IDA), fragility analysis, and seismic life cycle cost (LCC) evaluation. The obtained results demonstrate that the proposed retrofit is effective in reducing the maximum inter-story drift ratio (MIDR) significantly and in eliminating the residual drift. Additional engineering demand parameters, such as the floor acceleration and the base shear have been investigated to prove the superiority of the proposed retrofit technique compared to the fully rigid joint alternative. A finite element method (FEM) is used to ensure that concrete stresses after retrofit are within the acceptable limits. The retrofitted models show high energy dissipating potential compared to the bare cases. The IDA and fragility analyses show significant improvement in the retrofitted structures in terms of the median collapse capacity and seismic fragility. The probabilities of exceeding different limit states and the LCC of the retrofitted structures have been reduced significantly compared to the bare cases. Based on these findings, the proposed retrofit is recommended for similar structures to improve their resilience against earthquakes and to reduce the total seismic LCC.