Abstract:
Following the 2010 M7.1 Darfield Earthquake, the Davis Road Bridge, located 5 km southeast of Lincoln, New Zealand, sustained significant damage to the western approach. The single span bridge consisted of six double hollow core precast concrete beams with six square precast concrete piles and a 2.0 m long friction slab at each abutment. During the earthquake, lateral spreading caused the western approach to subside approximately 0.5 m. The subsidence of the approach effectively removed the stiffness provided by the abutment and provided a unique opportunity to directly measure the influence of this resistance on the system. The span was subjected to shaking along both axes from a large eccentric mass shaker and a benchmark system identification was made of the bridge in the damaged state. Soil was then recompacted, and the road repaved. Once the approach was reinstated, another round of shaking was performed, and differences in mode shapes and natural periods were compared between the damaged and reinstated states. Testing was able to detect one mode in each direction for the bridge both with and without both abutments intact.
