Lessons from structural analysis of a great gothic cathedral: Canterbury cathedral as a case study

Abstract

Damage in Gothic cathedrals can occur due to single extreme events or long-term processes, often associated with large deformations and cracking. This paper presents the damage survey and structural assessment of a UNESCO world heritage site and one of the oldest, most visited and most known Christian temples in the UK: Canterbury Cathedral, in Kent. Inspection and damage survey showed repetitive crack patterns on the vault's intrados, with more severity in the south aisle, including outward rotating movement and cracking in the south flying buttresses. Ambient vibration tests were carried out to identify the structure modal properties. An FE model of a typical transversal section of the nave and lateral aisles was prepared, and calibrated based on the tests. Nonlinear static analyses were performed, considering the main parameters of influence to the structure, as the construction process, the infill volume, the presence of lateral thrusts from the nave's roof and differential settlements. A validated FE model, presenting sufficient correlation with the existing damage was used to determine the safety factors for lateral and vertical loading, which according to the local hazard are considered adequate. A comparison with limit analysis, based on the static approach, was also carried out.