SEISMIC ANALYSIS OF MASONRY BUILDINGS

Abstract

In the past earthquakes, it was clearly visible that many masonry structures were damaged, partially and fully. Failure of masonry is still contributing the major part of threat to life safety. In India, over 85% of the population lives in masonry constructed houses from low to high seismic regions. Some specific features have been invented during the course of time to improve the seismic behaviour of masonry building, such as connecting stones, strengthening the corner and wall intersection zone, as well as tying the walls. In spite of availability of the provisions and recommendations of earthquake resistance measure to be applied in masonry building in the form of various codes, it still remains a common in India and other developing countries that these provisions are rarely implemented in actual practice. In order to reinforce the confidence level of user regarding various provisions of seismic codes a series of experiments have been conducted in the past to test the two systems (conventional and earthquake resistant model) on Shock Table at the Department of Earthquake Engineering, IIT Roorkee. The experimental studies carried out in the past consisted of tests on half scale model of one storied brick masonry house constructed simultaneously with and without seismic strengthening measures and tested under increasing intensity of shaking. In the study the pattern of cracking, identification of weak zone, mode of failure and damage with increasing intensity of shaking were studied and useful conclusions were drawn with respect to design of masonry buildings. The performance of earthquake resistant model was also compared. with the conventional model by testing both of them under same intensity of shaking. In the present study both conventional and earthquake resistant half scale brick masonry houses were modelled analytically using commercial software ABAQUS. A non-linear dynamic analysis was carried out by adopting concrete damaged plasticity as the material constitutive law. The execution of analysis is done by applying the same intensity of base acceleration as obtained from the experimental results. The roof acceleration of the model is obtained and compared with the experimental results. The damage pattern after every shock is obtained and compared with the experimental observation.