Seismic performance evaluation of steel buckling-restrained braced frames including SMA materials

Abstract

The permanent deformation of the building after seismic excitations can be determined by the Maximum Residual Interstory Drift Ratio (MR-IDR), which may be used for measuring the damage states. Low-post yield stiffness of the steel buckling-restrained braced frame (BRBF) makes this system vulnerable to large MR-IDR after a severe earthquake event. To overcome this issue, this paper investigates the seismic limit state performances of low- to mid-rise BRBFs with two- to eight-story levels (i.e. 2-Story, 4-Story, 6-Story, and 8-Story) adopting different lateral force-resisting systems using Viscous Dampers (VDs) and Shape Memory Alloys (SMAs). For this purpose, BRBFs improved with different implementation of SMAs and VDs, and Incremental Dynamic Analyses (IDAs) were performed based on Maximum Interstory Drift Ratio (M-IDR) and MR-IDR demands. Results showed that VDs and SMAs can decrease the values of maximum moment and rotation of hinges of structural members. Implementing both SMAs and VDs can significantly improve the seismic performance level and collapse failure probability of BRBFs more effectively than using one of the VDs or SMAs; then, it can be recommended to control the MR-IDR of BRBFs. To use the results, graphical user interface has been developed to estimate the improvements in the M-IDR and MR-IDR demands.