Experimental modal analyses of buildings during the Cook Strait earthquake sequence

Abstract

With the recent high levels of earthquake activity experienced throughout New Zealand there is a growing awareness of the need for quick and reliable determination of whether buildings are safe to work and live in. In parallel, on-going advances in sensor technology worldwide have resulted in the potential for new and innovative sensing systems which could change the way that civil infrastructure is monitored, controlled and maintained. A number of data sets from computational and laboratory analyses are readily available that provide information on the seismic response of buildings, but there are a limited number of data sets currently available worldwide that have building response records from real ground motions. Following the 21 July 2013, MW 6.5 Cook Strait earthquakes, a number of buildings in the Wellington Central Business District (CBD) were instrumented with low-cost accelerometers. During the period from 19 July - 16 August, 2013 there were more than 2500 aftershocks in the magnitude range of 2.0 - 6.6, and these sensor arrays were able to collect high quality building response data sets. A summary of the data analysis for six structures that were instrumented during the Cook Strait earthquake sequence are presented, along with the major challenges and opportunities related to the future monitoring of existing civil infrastructure.