Residual drift risk of self-centering steel MRFs with novel steel column bases in near-fault regions

Abstract

This paper evaluates the potential of novel steel column bases to reduce the residual drift risk of steel buildings located at near-fault regions when installed to post-tensioned self-centering moment-resisting frames (SC-MRFs). To this end, a prototype steel building is designed that consists of either conventional moment-resisting frames (MRFs) or SC-MRFs or SC-MRFs equipped with the novel steel column base (SC-MRF-CBs). The MRFs and SC-MRFs are used as benchmark frames. The frames are modelled in OpenSees where material and geometrical non-linearities are considered along with stiffness and strength degradation. A set of 91 near-fault ground motions with different pulse periods is used to perform incremental dynamic analysis (IDA), in which each ground motion is scaled appropriately until different residual storey drift limits are exceeded. The probability of exceedance of these limits is then computed as a function of the ground motion intensity and the period of the velocity pulse. Finally, the results of IDA are combined with probabilistic seismic hazard analysis models that account for near-fault directivity to evaluate and compare the residual drift risk of the frames used in this study. Results show that the predicted residual drift performance of the frames is influenced by the pulse period of the near-fault ground motions. The use of the novel steel column base significantly reduces the residual drift risk of the frames and the SC-MRF-CB exhibits the best residual drift performance. Finally, the paper highlights the effectiveness of combining post-tensioned beam-column connections with the novel steel column base, by showing that the SC-MRF-CB improves the residual drift performance of the MRF and SC-MRF by 80% and 50%, respectively.