Investigation of the effect of using isotropic and anisotropic modelling techniques to study the cracking in masonry walls due to thermal movements of an overlying slab

Abstract

Use of roof slabs in Sri Lankan buildings is getting popular especially in commercial buildings and hotels, and even in some residential buildings. In a tropical country like Sri Lanka, roof slabs are exposed to direct solar radiation over more than eight hours per a day. Concrete slabs exposed to direct sunlight experience thermal movements. These movements can result in over stressing and cracking in underlying masonry walls. Due to the presence of vast range of geometrical and structural configurations, use of physical models to investigate the behaviour of masonry is a costly and a difficult exercise. As a solution, finite element modelling is widely used in investigation of masonry. Masonry is a composite material that exhibits distinct directional properties due to the presence of mortar joints. Therefore, it is important to study the effect of the presence of these joints considering masonry as an anisotropic material rather than an isotropic material in numerical studies. This paper describes a numerical modelling exercise employed to understand the above effect related to the modeling of cracking in masonry walls due to thermal movements of an overlying slab. Further, models were used to study the effect of the aspect ratio, structural form and presence of other geometrical features such as openings and lintels on the above phenomenon. Also, the results were used to propose remedial measures to the problem. It was found that the pattern (type and location) of cracking depends significantly on the structural and geometric features of the wall and anisotropic approach can predict better results when structural and geometric features become complicated.