Enhancing the Seismic Performance of Precast Concrete Diaphragms With Shape Memory Alloy Connectors

The seismic performance of precast concrete diaphragms is critically dependent on the efficiency and resilience of their connectors. This thesis explores the feasibility of incorporating Shape Memory Alloy (SMA) connectors as an alternative to traditional steel connectors. A comprehensive investigation was conducted to compare the performance of steel and SMA connectors in precast diaphragm applications. The results highlight the limitations of steel connectors, including residual deformations, stiffness degradation, and susceptibility to fatigue. A novel hybrid connector system was developed, comprising an SMA-based tension connector and a complementary shear-only steel connector. The proposed design was integrated into a realistic diaphragm configuration and assessed under cyclic loading, simulating seismic action. The findings confirm that SMA connectors significantly enhance diaphragm resilience by eliminating residual displacements, improving ductility by 25%, increasing ultimate deformation capacity by 400%, and providing a 46% increase in energy dissipation. This research contributes to advancing seismic design methodologies by demonstrating the practical implementation of SMA connectors within ASCE 7-22 guidelines.