Geometric characterisation and out-of-plane seismic stability of low-rise unreinforced brick masonry buildings in Auckland, New Zealand

Abstract

The 2010-2011 Canterbury earthquakes and corresponding Royal Commission reports have resulted in changes to the legislative environment and led to increased public awareness in New Zealand of the earthquake performance of unreinforced masonry (URM) buildings. As a result, building regulators, owners, tenants, users and heritage stakeholders will be facing a unique challenge in the near future where assessments, improvements and demolitions of URM buildings are expected to occur at an unusually high rate. Auckland is the largest city in New Zealand and because of the relative prosperity of Auckland during the period 1880-1935 when most URM buildings were being constructed in New Zealand, the city has the largest number of URM buildings in the country. Identifying those buildings most at seismic risk in Auckland’s large and varied building stock has warranted a rapid field assessment program supplemented by strategically chosen detailed assessments. Information that can be procured through rapid field inspections includes the building geometric typologies (e.g., heights, building footprint geometry and isolated versus row configuration), elevation type (e.g., perforated frame versus solid wall), wall construction (e.g., solid versus cavity, number of leaves) and basic construction material type (e.g., clay brick versus stone). Furthermore, investigation into the architectural history, heritage status and functional usage of Auckland’s URM buildings will affect the direction of retrofit strategies and priorities. As the owner of a large and varied portfolio of URM buildings as well as the local organisation responsible for assessing building safety, Auckland Council is developing exemplar inspection, assessment, prioritisation and retrofit strategies that will target the seismic risks associated with URM buildings, in particular, so as to preserve and enhance safety and the economic and community value of these special buildings. Collaboration amongst Auckland Council, The University of Auckland and GNS Science has resulted in a state-of-the-art rapid quantitative assessment program applied to a sampling of typologically representative URM buildings in Auckland.