An evaluation of the incidence of soil subsidence on the dynamic behaviour of a Gothic bell tower

This paper describes a study carried out on the bell tower of the Church of Santas Justa and Rufina in Orihuela in the Province of Alicante, Spain. The study was made to predict the evolution of its dynamic behaviour in relation to subsidence caused by variations in the level of the water table during periods of drought. Initial calibration of the developed numerical model was based on the dynamic characteristics of the tower in free vibration. The numerical model included details of both the structure and the surrounding terrain to a depth of ten meters, as indicated by geotechnical tests. Sensitivity studies were made of the terrain’s elastic characteristics with the aim of evaluating the dynamic amplification factor of the soil–structure interaction due to dynamic forces generated by the swinging of the bells in the tower.