UBC Theses and Dissertations

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UBC Theses and Dissertations

Life cycle thinking based performance evaluation of shape memory alloy reinforced bridges under seismic conditions Wanniarachchi, Sandun Tharaka


A severely damaged bridge due to an earthquake could result in fatalities and injuries, disturb the transportation infrastructure system, and would incur significant repairing costs. Furthermore, it is vital that bridges stay functional following an earthquake and serve as escape routes for emergency vehicles. It is not feasible to design a bridge to behave elastically during major earthquakes. Hence, it is important that innovative high-performance mechanisms or materials are used in structures located in seismic regions. Recent studies show that bridges reinforced with shape memory alloys (SMAs) demonstrate improved performance when subjected to seismic loads. In general, the initial cost of a bridge using SMA is high because SMA reinforcement is expensive and requires special workmanship. However, when accounting the post-earthquake repair and maintenance costs, SMA bridges pose significant cost advantages over conventional structures in the long run. Thus, in this study, the performance of three concrete bridges reinforced with SMAs in the plastic hinge regions was compared with a similar bridge reinforced with conventional steel. A fragility analysis was conducted on each structure to assess their seismic vulnerability. A life cycle cost (LCC) assessment was done on each structure to determine the economic impacts caused during their service life. A cradle-to-grave life cycle assessment (LCA) was done on those structures using SIMAPro in order to assess their environmental impacts. The seismic performance, LCC, and LCA results for each structure for numerous scenarios under uncertain performance conditions were put into a framework to compare the overall life cycle performance of the structures with each other. The uncertainty in the data was incorporated by using fuzzy logic in the decision matrix. The results of this study will assist engineers and the construction industry as a whole in making informed decisions regarding bridge type selection under multiple perspectives, accounting for uncertain conditions.

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