Browsing by Author "Haadi, MSB"

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item: Conference-Full-text
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
(2013-12-01) Haadi, MSB; Dilrukshi, KGS
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.
item: Conference-Extended-Abstract
Numerical modelling of cracking of masonry walls due to thermal movements of an overlying slab
(2010) Haadi, MSB; Gunasekera, DN; Rathnasekara, KSK; Dilrukshi, KGS
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.