Thesis Format
Monograph
Degree
Master of Engineering Science
Program
Civil and Environmental Engineering
Supervisor
Youssef, Maged A.
Abstract
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.
Summary for Lay Audience
During earthquakes, buildings are subjected to forces that can cause damage or collapse. The diaphragm (floor/roof slab) is a critical component that helps buildings withstand earthquakes. This structural component transfers forces between floors and walls. The diaphragms can be made of precast concrete panels connected using steel components. However, traditional steel connectors tend to bend permanently after strong shaking, making repairs difficult and expensive. This study explores a new type of connector made from Shape Memory Alloys (SMAs). Unlike regular steel, SMA can return to its original shape after deforming. This feature means that a building using SMA connectors would not experience significant permanent damage after an earthquake, making repairs quicker and cheaper. Using computer simulations, this research compared the behaviour of steel and SMA connectors during an earthquake. The results showed that steel connectors often remained bent and weakened after shaking. In contrast, SMA connectors retained their shape and continued to function properly. A new connector system was designed using SMA-based tension and steel-based shear connectors. This combination ensured that the structure could both withstand shaking and recover efficiently. Replacing traditional steel connectors with SMA connectors could make buildings safe and repairable after an earthquake. While SMAs are expensive upfront, their ability to reduce post-earthquake repairs may make them a valuable investment in earthquake-prone regions. Future research should focus on testing these connectors in real-world conditions and refining design standards to encourage their use in construction.
Recommended Citation
Dodd, Jeremy, "Enhancing the Seismic Performance of Precast Concrete Diaphragms With Shape Memory Alloy Connectors" (2025). Electronic Thesis and Dissertation Repository. 10749.
https://ir.lib.uwo.ca/etd/10749