Experimental study on re-centering behavior and energy dissipation capacity of prefabricated concrete frame joints with shape memory alloy bars and engineered cementitious composites

To enhance the seismic performance of prefabricated concrete frame joints, an innovative prefabricated beam -column joint with shape memory alloy (SMA) and engineered cementitious composite (ECC) materials was proposed in this paper. Four 1/2-scale test specimens, including one SMA-ECC prefabricated beam-column joint and three comparison joints (namely particularly reinforced concrete cast in situ joint, ordinary concrete pre-fabricated joint, and ECC-reinforced prefabricated joint) were designed and fabricated. A new type of semi -mechanical sleeve connector was designed to link the SMA bar with the longitudinal reinforcement of the pre-cast beam. Through the low-cycle reciprocating loading tests on the specimens, the failure mechanism, bearing capacity, and self-centering performance of each frame joint were studied. The results show that post-pouring ECC in the plastic hinge zone of beam-column joints can significantly improve the cracking failure form and the ductility of the joints. Though the initial stiffness and energy dissipation capacity of the structure are slightly reduced when SMA and ECC are applied to the prefabricated beam-column joints. Nevertheless, the new com-posite materials can significantly enhance the ductility and self-centering capacity, reduce the residual defor-mation and the stiffness degradation rate of the structure. The SMA-ECC reinforced prefabricated beam-column joint can achieve better functional self-resilience ability after earthquake.