Collapse risk evaluation of self-centering steel MRFS with viscous dampers in near-fault regions

This paper presents an evaluation of the seismic collapse risk of self-centering moment-resisting frames (SC-MRFs) with viscous dampers located in near-fault regions. This evaluation is based on the comparison of different designs of a prototype steel building using four lateral load resisting frames: 1) conventional moment-resisting frames (MRFs), 2) MRFs with viscous dampers, 3) SC-MRFs and 4) steel SC-MRFs with viscous dampers. The frames are modeled in OpenSees where material and geometrical nonlinearities are taken into account as well as cyclic strength and stiffness degradation. A database of 91 near-fault, pulselike ground motions with varying pulse periods is employed for the nonlinear dynamic analyses. Collapse resistance of the frames is evaluated through incremental dynamic analysis (IDA). The results of the IDA are combined with probabilistic seismic hazard analysis models that account for near-fault directivity to assess collapse risk of the structures. Results show that the predicted collapse capacity is affected by the pulse period of the near-fault ground motions and highlight that self-centering connections can significantly improve the collapse resistance of conventional MRFs. Finally, it is shown that supplemental damping provides superior collapse resistance for all frames.