Seismic Retrofitting Strategies and Engineering Solutions of Kanaka Creek Bridge on Highway 7

Kanaka Creek Bridge carries Highway 7 over Kanaka Creek in Maple Ridge, British Columbia. This paper presents the seismic evaluation and retrofit design adopted for the Kanaka Creek Bridge. Response spectrum analysis was performed under three seismic hazard levels to evaluate seismic performance of the bridge structure. Capacity over demand ratios were employed as main indicators for seismic assessment of critical bridge structural components and connection elements in the seismic load path. Pushover analysis was performed at the abutments to understand the structural performance of the steel pipe piles after yielding. Given the potential of abutment soil liquefaction during seismic events, soil lateral spreading effects and vertical downdrag effects on steel pipe piles were evaluated. After identifying the potential structural failure mechanism, the designers proposed performance-based seismic retrofitting solutions with additional drilled-in steel dowel at bridge abutments and link slabs at bridge deck over piers. This seismic retrofitting scheme provides deck continuity, improves the longitudinal load path and strengthens the connections between superstructure and substructure. The project was completed on time and within the approved budget.