Seismic Response of an Instrumented Reinforced Concrete Bridge Subjected to Varying Excitation Levels

Abstract

The Awatere River Bridge, located in the north-eastern region of the South Island of New Zealand, has experienced a number of earthquakes since its construction in 2007. This includes the Cook Strait earthquake sequence in 2013, the 2016 Kaikoura earthquake and their aftershocks. The damage was evident after two of these events, with cracking and spalling of a number of the piers, and as a result, there were repairs carried out after both events. Following each of these events, a network of triaxial accelerometers was installed to monitor its response, including free field motions. In this study, the records from the bridge monitoring network were used to develop and calibrate finite element models of the bridge, and the structural and geotechnical characteristics. The acceleration records, the damage locations, and severities after each event were used as part of this calibration process and the progressive change in dynamic properties after each large event. Sensitivity analyses were performed to assess the influence of a range of structural and geotechnical characteristics on system response. In general, there was good agreement between the recorded and modeled bridge response, which required the incorporation of details from post-event surveys of changes in pier heights due to scour effects. Modeling also highlighted the importance of assumptions related to the representation of abutment characteristics.