SIMPLIFYING BRIDGE MODELS FOR FRAGILITY ANALYSIS

A large portion of the Central and Southeastern United States is defined as a potential hazard for seismic activity. Project DS-7b analyzes bridges typical to this region and ultimately produces fragility curves for these bridges. A fragility curve is a probabilistic way of assessing the vulnerability that a bridge, or any structure, has to a seismic event. Programs such as OpenSEES are used to build bridge models, and their fragility curves are then generated using programs such as MATLAB. Unfortunately, when these models become very complex, their analysis consumes a large amount of time. This report presents a simplified model as a somewhat viable alternative to a complex model for fragility analysis, subject to two different suites of ground motions. This analysis is found to produce significantly less program run-times while resulting in component responses comparable to those of the complex model. Finally, the fragility curves for both the simple and complex models, taking many uncertainties into account, are plotted and compared