DAMAGE IN PATRIMONIAL MASONRY STRUCTURES

Abstract

Initiation and propagation of cracks inside a composite material made of bricks and stones bound with a traditional lime mortar remains a very complicated problem, may be just solved today for very simple geometries and loadings with help of theoretical models of behavior and homogenization theory. For real structures under complex loadings, like a patrimonial building, such models are unusable and more crude ones are necessary for preparation of preservation engineering interventions. This paper describes a study aiming mainly to simulate cracks initiation and propagation with resulting damage inside the masonry foundation of the choir of O-L cathedral in Tournai (12^th and 13^th century, Unesco World Heritage). The analysis is based on a reliable full 3D geometric model taking into account the structure and the masonry foundation settled partly on soft soils and partly on bedrock. All the materials involved in the study are assumed to be linear elastic. Crack initiation is based on a criterion of maximum principal tension stress. Crack propagation is simulated by successive geometric modifications (disconnections between nodal points) inside the model and new analysis. The obtained results allow a satisfactory understanding (much better than the previously obtained with very simplified models) of experimentally observed pathologies and give confidence to the adopted computational method. Based on obtained results a scheme of the actual damaged state of the masonry foundation is proposed. It is quite useful for engineers in charge of structural repairing works.