Assessing the residual capacity and future performance of the Mason River Bridge, NZ

On 14 November 2016, the Mason River Bridge in North Canterbury, New Zealand, was rocked by one of the most complex and violent earthquakes ever recorded. This resulted in significant plastic hinging at the base of the pier columns. To avoid major costly repairs and strengthening, an innovative hardness and material testing technique was employed to determine the damage to reinforcement and residual capacity of the plastic hinges. This technique was developed for damaged buildings following the 2010 and 2011 Christchurch earthquakes, and is the first known example of its use for an earthquake-damaged bridge. Coupled with detailed non-linear time history analysis of the structure, this testing and analysis allowed the bridge's current and future seismic performance to be determined and helped justify the use of more conventional repairs, with major strengthening and seismic retrofit being avoided. This paper discusses the earthquake damage observed, the seismic performance of the structure, the advantages and disadvantages of the innovative material testing techniques, maintenance and repairs to the bridge and the expected performance of the repaired columns