Seismic vulnerability assessment of wall pier highway bridges in British Columbia

British Columbia, recognized as the most earthquake prone region in Canada, has a transportation network consisting of more than 2500 highway bridges. Failure of bridges due to any future seismic event might have a catastrophic impact on the province’s highway network. Many of the bridges in this region are very old and were constructed without proper seismic detailing. Moreover, by introducing performance based design (PBD) approaches in the proposed Canadian Highway Bridge Design Code (CHBDC), probabilistic seismic assessment of existing bridges have become essential. In this study, fragility analysis is performed to assess the seismic performance of the existing wall pier highway bridges in BC which is one of the major bridge types in BC region. Fragility curves for critical bridge components and for the entire bridge system are generated which provide the probability of exceeding any specific performance level under a certain ground motion intensity. Estimation of wall pier capacity limit states for these different performance levels is also part of this study which is crucial for performance based design of wall pier bridges. In order to accurately simulate the behavior of such wall pier bridges in BC, a comprehensive bridge inventory analysis is performed to determine their dimensions, shapes, span length etc. Analytical 3D models of 180 wall pier bridges with three different soil types, as per CHBDC, are generated combining different structural and geometrical uncertainties from the inventory. From the nonlinear dynamic time history analyses of these bridge models, fragility curves for slight, minimal, repairable and near collapse damage are generated. Fragility curves highlight the elastomeric bearing as the most vulnerable component followed by wall pier and abutment back wall. While estimating the seismic vulnerability, these fragility curves can also provide resourceful information for developing a retrofitting prioritization plan for wall pier bridges in BC. Besides the information presented in the inventory will aid in establishing an efficient Bridge Management System (BMS) and a possible National Bridge Inventory for Canada.Applied Science, Faculty ofEngineering, School of (Okanagan)Graduat