Damage inspection in churches : the Canterbury Earthquake (New Zealand) experience

Abstract

The Canterbury Region of New Zealand experienced an extensive earthquake sequence during 2010-2011, with two particularly sever events being on September 4, 2010 and February 22, 2011. The present work entails a statistical analysis of the data for 112 churches in the affected region, including in situ damage observed by the authors and the structural assessment classification assigned by the local authorities, allowing for the discussion of the seismic performance of these churches separated in three main typologies: i) stone masonry; ii) clay brick masonry churches; iii) timber churches. A simplified method of assessment of large span masonry structures, which had already been applied to a database of 44 monuments in Italy, Portugal and Spain, was applied with the objective of validating the proposed thresholds. A set of fragility curves, with the objective of estimating damage as a function of the peak ground acceleration, is also provided. It was concluded that the timber churches had an excellent seismic performance, registering only non-structural damage, while the stone and clay brick churches clearly performed unsatisfactorily. The simplified method, which includes three separated indexes, presented very good results for one index (plan area ratio), and acceptable results for the other two (weight ratio and base shear ratio).