Seismic Assessment of St James Church by Means of Pushover Analysis – Before and After the New Zealand Earthquake

The paper presents a numerical study for the seismic assessment of the St James Church in Christchurch, New Zealand affected by the recent 2011 earthquake and subsequent aftershocks. The structural behavior of the Church has been evaluated using the finite element modelling technique, in which the nonlinear behavior of masonry has been taken into account by proper constitutive assumptions. Two numerical models were constructed, one incorporating the existing structural damage and the other considering the intact structure. The validation of the numerical models was achieved by the calibration of the damaged model according to dynamic identification tests carried out in situ after the earthquake. Non-linear pushover analyses were carried out on both principal directions demonstrating that, as a result of the seismic action, the Church can no longer be considered safe. Pushover analysis results of the undamaged model show reasonable agreement with the visual inspection performed in situ, which further validates the model used. Finally, limit analysis using macro-block analysis was also carried out to validate the main local collapse mechanisms of the Church.