Numerical modelling of cracking of masonry walls due to thermal movements of an overlying slab

Abstract

Concrete slabs exposed to direct sunlight experience temperature related horizontal movements. In addition, temperature of the top surface of the slab reaches higher temperature than the bottom, causing an upward deflection of the slab during heating. In a typical building, masonry and concrete elements restrain each other at their respective interface. Therefore significant movement would be generated on the masonry walls, due to movement of the roof slab. These movements can result in overstressing and cracking in masonry. Therefore in the buildings with roof slabs, cracking of walls which are located immediately under the roof slab has become a considerable problem. In this study stresses indicated on the masonry walls due the thermal movement of the roof slab were investigated using three dimensional finite element models. Location and direction of possible cracks were identified using a failure criterion developed based on principal stresses. Using the finite element models, the effect of the aspects ratio of wall, structural form (i.e. load bearing and reinforced concrete framed walls), and presence of other geometrical features such as opening and lintels on the above phenomena were identified. In addition, the effect of modeling masonry as an anisotropic material rather than as isotropic material was investigated.