Seismic Performance of Nine-Story Self-centering Buckling-Restrained Braced Frames

摘要

Buckling-restrained braces (BRBs) are the special type of braces used in lateral force-resisting systems in structures located in high-seismic regions worldwide. The main advantages of BRBs are the symmetrical hysteretic response, high ductility, and excellent energy dissipation potential as compared to the conventional steel braces. Past studies have shown that the lack of re-centering capability of BRBs may result in the excessive post-earthquake residual displacement of the braced frame, which may not be cost-effective for repair and retrofit. To minimize the residual drift response of buckling-restrained braced frames (BRBFs), the self-centering mechanism should be fitted in braces. Such braces are termed as SC-BRBs. The shape memory alloy (SMA) rod which uses along with the BRB is relatively costly, to optimize the use of SMA rod along the BRB with effective re-centering capability is the aim of the present study. The evaluation of present study is focused on the seismic response of BRBFs with shape-memory-alloy-based SCBRBs under the near-field earthquake ground motions. A nine-story building has been considered for this numerical study. The present study frame is designed in accordance with current American seismic code (AISC 341 in Seismic provisions for structural steel buildings 341,) and is modeled and analyzed using a computer software OpenSees (Mazzoni et al. in OpenSees command language manual,). Forty near-field ground records are selected in the nonlinear dynamic analysis. The main parameters investigated are inter-story drift response and residual drift response with varying SMA uses. The analysis results for more use of SMA in the SC-BRBFs showed the better re-centering capability with marginally higher inter-story drift response.