Seismic Performance Comparison of New Zealand and Japanese Concrete Moment Frames

Abstract

Observations of the performance of reinforced concrete (RC) buildings after the 2016 Kumamoto earthquake in Japan showed buildings designed using Japanese standards resulted in less damage and downtime compared to buildings following the 2010/2011 Christchurch earthquakes in New Zealand. To evaluate the underlying reasons for the observed difference in performance, this paper compares the seismic performance of RC moment frame buildings designed according to seismic design philosophies from New Zealand and Japan. Specifically, a case study building located in Dunedin was designed using New Zealand material properties, but with scaled seismic demands and design requirements based on the New Zealand and Japanese standards. The performance of the two buildings was compared using a suite of 78 ground motions selected for various magnitudes of expected seismic hazards in Dunedin. The Japanese moment frame design was controlled by a 0.5% drift limit per Japanese Building Standard Law (BSL) whereas the New Zealand moment frame design was controlled by gravity loading and minimum detailing per NZS 3101. The Japanese requirements result in moment frames with larger section sizes, but lower reinforcement ratios and smaller beam-to-column strength ratios compared to frames designed to New Zealand specifications. For moderate earthquake intensities, the New Zealand frame had larger peak median inter-storey drifts with increasingly larger differences compared to the Japanese frame with not much difference in peak median floor accelerations.