Enhancing seismic performance of rigid and semi-rigid connections equipped with SMA bolts incorporating nonlinear soil-structure interaction

• A comprehensive investigation performed on the seismic vulnerability assessment of the Steel Moment-Resisting Frames (SMRFs) with semi-rigid connection. • Nonlinear Soil–Structure Interaction (SSI) were considered to assume the real condition of models founded on four soil types. • Semi-rigid connections significantly decreased the seismic performance levels and the seismic probability of collapse. It is suggested to consider the rigidity of connection and SSI effects in the vulnerability assessment of SMRFs. • Shape Memory Alloys (SMAs) bolts were used in semi-rigid connections to improve their seismic behavior. This method can be adopted as retrofitting strategy for already existing building. Nowadays, using smart connections can improve the performance of buildings with some recentering features that are from the superelastic behavior of Shape Memory Alloys (SMAs). It seems that there is different rigidity between the designed connection and the real one in Steel Moment-Resisting Frames (SMRFs), which can be considered as a problematic issue due to the importance of connections in seismic performance assessment. This paper aims to investigate the seismic limit-state capacities of rigid and semi-rigid connections implemented in the 3-Story, 5-Story, 7-Story, and 9-Story SMRFs considering the nonlinear Soil-Structure Interaction (SSI) effects. A Tcl programming code was developed to model semi-rigid connection and SSI effects using Opensees. Incremental Dynamic Analyses (IDAs) were employed to assess the seismic performance levels of SMRFs considering Near-Fault Pulse-Like (NF-PL) and Near-Fault No-Pulse (NF-NP) records suggested by FEMA-P695. The results showed that assuming semi-rigid connections with rigidity of 80%, 70%, and 60%, significantly decreased the median values of IDA curves compared to rigid connection. Considering the SSI effects can considerably decrease the S a ( T 1 ) values of IDA curves and seismic collapse probability in all soil types; therefore, it is suggested to assume the real condition of the structure by modeling the connection rigidity and the SSI effects. It can be concluded that SMA bolts have the ability to improve the seismic performance of connection to compensate the lack of rigidity in semi-rigid connections of SMRFs; as well as, they can be used as a retrofitting strategy for existing buildings.