Experimental Earthquake Response of Two-Storey Scaled URM Buildings

Abstract

As an immediate response following the 14 November 2016 the Mw 7.8 Kaikoura, New Zealand earthquake, the Ministry for Business, Innovation and Employment together with representatives from local government, researchers and practitioners discussed possible strategies for how to address the elevated risk of fatalities posed by unreinforced masonry (URM) facades and parapets. The outcome from the discussion was a policy that requires securing of street-facing parapets and facade with a particular focus on heritage precincts with high pedestrian traffic. Implementation of the policy is currently ongoing and an experimental campaign has been initiated to provide building owners and practicing engineers with a better understanding of the performance of different levels of building strengthening and also propose simple, speedy and cost-effective retrofit solutions. The experimental campaign involved replication of the earthquake behaviour of scaled two-storey unreinforced clay brick masonry buildings using a shake-table. The building performance was first tested in the as-built condition in order to establish a benchmark for the proposed retrofit techniques. Two different levels of strengthening were investigated: (i) simple wall-to-diaphragm connections, (ii) additional vertical strong-backs installed on the top floor wall interior surface and moment-resisting frames placed at the ground floor. Scaled building and material characteristics as well as the obtained results during the shaking table tests in terms of response of the structure, damage mechanisms and performance achieved are reported herein.