Shape memory alloys are a class of alloys that display the unique ability to undergo large plastic deformations and return to their original shape either through the application of heat (shape memory effect) or by relieving the stress causing the deformation (superelastic effect). This research takes advantage of the unique characteristics of shape memory alloys in order to provide a moment resisting connection with recentering capabilities. In this study, superelastic Nitinol, a nickel-titanium form of shape memory alloy that exhibits a flag-shaped stress versus strain curve, is used as the moment transfer elements within a partially restrained steel beam-column connection. Experimental testing consists of a one-half scale interior connection where the loading is applied at the column tip. A pseudo-static cyclic loading history is used which is intended to simulate earthquake loadings. The energy dissipation characteristics, moment-rotation characteristics, and deformation capacity of the connection are quantified. Results are then compared to tests where A36 steel tendons are used as the moment transfer elements. The superelastic Nitinol tendon connection showed superior performance to the A36 steel tendon connection, including the ability to recenter without residual deformation.

Epidemic models help researchers understand and predict the nature of a potential epidemic. This study analyzes and improves network evolution technology that evolves contact networks so that simulated epidemics on the network mimic a specified epidemic pattern. The evolutionary algorithm incorporates the novel recentering-restarting algorithm, which is adopted into the optimizer to allow for efficient search of the space of networks. It also implements the toggle-delete representation which allows for broader search of solution space. Then, a diffusion character based method is used for analyzing the contact networks. A comparison of simulated epidemics that result from changing patient zero for a single contact network is performed. It is found that the location of patient zero is important for the behaviour of an epidemic. The social fabric representation is invented and then tested for parameter choices. The response to vaccination strategies (including ring vaccination) is then tested by incorporating them into the epidemic simulations. / Ontario Graduate Scholarship (OGS), Natural Sciences and Engineering Research Council of Canada (NSERC)

In an effort to mitigate damage caused by earthquakes to the built environment, civil engineers have been commissioned to research, design, and build increasingly robust and resilient structural systems. Innovative means to accomplish this task have emerged, such as integrating Shape Memory Alloys (SMAs) into structural systems. SMAs are a unique class of materials that have the ability to spontaneously recover strain of up to 8%. With proper placement in a structural system, SMAs can act as superelastic "structural fuses", absorbing large deformations, dissipating energy, and recentering the structure after a loading event. Though few applications have made it into practice, the potential for widespread use has never been better due to improvements in material behavior and reductions in cost. In this research, three different SMA-based structural applications are developed and tested. The first is a tension/compression damper that utilizes nickel-titanium (NiTi) Belleville washers. The second is a partially restrained beam-column connection utilizing NiTi bars. The third is an articulated quadrilateral bracing system utilizing NiTi wire bundles in parallel with c-shape dampers. Each system was uniquely designed to allow a structure to undergo large drift demands and dissipate energy while retaining strength and recentering ability. This exploratory work highlights the potential for SMA-based structural applications to enhance seismic structural performance and community resilience.