Comparison of predicted and observed seismic performance of Kekerengu and Tirohanga Bridges during Kaikoura 2016 earthquake

On November 14, 2016 at 12:02 a.m. local time, the M_w 7.8 Kaikoura earthquake occurred along the east coast of the upper South Island, New Zealand. The earthquake affected a relatively large area and significant impacts occurred to the horizontal infrastructure in the region. This paper focuses on the effects of the ground shaking on two bridges – Tirohanga Stream Bridge and Kekerengu River Bridge along State Highway 1 (SH1). As a result of this earthquake, a new bridge and associated embankments have been constructed at the Tirohanga site and the Kekerengu Bridge has been repaired. One year prior to this earthquake, the same two bridges were the subject of a geotechnical and structural seismic assessment initiated by the New Zealand Transport Agency (NZTA) as part of a programme for assessing the seismic performance of bridges on national strategic routes. This paper compares the predicted seismic performance of the bridges prior to the earthquake and their observed performance during the Kaikoura earthquake. It provides lessons learned for young geotechnical engineers to consider for seismic assessments of existing structures and valuable insights into their performance, and how uncertainties can be accounted for.