Jason M. Ingham¹, Shannon Abeling¹, Stacy Vallis ¹, Francisco Galvez¹, Moustafa Swidan¹, Michael C. Griffith², and Jaroslav Vaculik²

1) Dept. of Civil and Environmental Eng, University of Auckland, Auckland (New Zealand)

e-mail: j.ingham@auckland.ac.nz; {sabe321, sval034, fglv390, mswi136}@aucklanduni.ac.nz

2) School of Civil, Environmental and Mining Eng, University of Adelaide, Adelaide (Australia)

{michael.griffith, jaroslav.vaculik}@ adelai e.edu.au

Keywords: Unreinforced masonry, Precincts, Scenario studies, Fragility curves.

Abstract. The nature of urban development in New Zealand and Australia followed a similar pattern, with communities frequently having a high density of unreinforced masonry (URM)  buildings at their civic centre due to the early colon al practice of repeating the style of building architecture that was fashionable in the United Kingdom during the mid and late 1800s when the two countries experienced European colonisation.

Following the 2010/2011 Canterbury earthquakes approximately 90% of the unreinforced masonry buildings that had been prevalent throughout the Christchurch Central Business District were demolished, either because of severe building damage or because their cost of repair was excessive with respect to the insurance cover and the price of a new replacement building. This outcome has led to a complete change of character to the city, with very few historic buildings now remaining. These events have also underscored that similar scenarios can be expected throughout New Zealand and Australia if future earthquakes were to generate high intensity ground shaking to these URM precincts.

In response to the above issues, a joint NZ-Australia research project was undertaken to investigate appropriate ground shaking scenarios and survey specially selected URM precincts. These surveys accounted for URM building construction characteristics that would influence their expected earthquake response.  Pedestrian and building occupancy data were also estimated. Using empirical data from the Canterbury earthquakes, building fragility functions, volume-loss models, falling debris relationships, and correlated casualty relationships were developed. These relationships were then applied to the earthquake scenarios to understand the likely impacts in terms of building performance and damage, the extent of casualties, impacts on cordoning decision and economic disruption, plus the benefits to be derived from a pro-active approach to seismic retrofit implementation.