Advanced Seismic Design of Multi-Span Bridges in a Challenging Seismic and Geotechnical Environment
- Publication no: ABC-DES701-14
- Published: 22 October 2014
The MacKays to Peka Peka Project is an 18 km section of the new Kapiti Expressway, which passes through the Kapiti Region, 60 km north of Wellington, New Zealand. The key role of the Expressway is to provide a modern and reliable route which safely crosses over the local roads and waterways and bypasses the local town centres. The high seismicity of the area and poor soils present numerous challenges to the designers. This paper presents the seismic design approach adopted for the multi-span bridges on the MacKays to Peka Peka Expressway Project and discusses multi-span bridge concepts to accommodate the non-linear soil structure interaction in non-liquefied and liquefied ground conditions under very high seismicity. The approach pushes the boundaries of current seismic design as New Zealand moves from a force-based design to a displacement-based design approach. Furthermore, the paper explains the modelling techniques to capture the non-linear pushover analysis of the structures. The paper also demonstrates how multi-span bridge structures can be designed economically with an acceptable level of damage through improved understanding of their non-linear soil response and structural behaviour.