HYSTERETIC PERFORMANCE ANALYSIS OF SELF-CENTERING BEAM-COLUMN CONNECTIONS WITH SMA BARS AND FRICTION ENERGY DISSIPATOR

By introducing NAO (non-asbestos organic material) friction energy dissipator and superelastic SMA (Shape Memory Alloy) bars into beam-column connections, a self-centering connection with friction devices (NAO-SMA-SC) was proposed, effectively dealing with both the large residual drift and the lower energy dissipation of traditional connections after earthquake. In this paper, the details and working mechanism were analyzed. Due to the large strain demand of SMA bars, based on the Lagoudas model, a strain-hardening modified model of SMA bars was presented. Adding the proposed model to the finite element software OpenSees, the analysis model of NAO-SMA-SC connections was developed to study the mechanical behavior of SMA bars, NAO friction devices and gap element during the rotation of connections under the cyclic loading condition. The influences of several key parameters, including the friction force F_f, the diameter D and initial strain P of SMA bars, on the hysteretic performance of NAO-SMA-SC connections were analyzed systematically. The results show that the friction device could significantly improve the resisting moment and energy dissipation ability of connections, meanwhile increase the residual drift. The enlargement of SMA diameter could promote the moment and self-centering effect of connections. Pre-stressing the SMA bars could effectively reduce the residual drift of connections.