SEISMIC VULNERABILITY OF ECCENTRIC BUILDINGS

Lots of research effort has been directed in recent times towards seismic vulnerability assessment. This is a part of seismic disaster mitigation. Earthquake Engineers can contribute in the noble cause by understanding and predicting structural behaviour under seismic action as close as the actual one and providing the structure safe capacities against all the possible demands during strong motion. Seismic vulnerability assessment exercise poses several difficulties as demand and capacity calculations depend not only on earthquake parameters but also on the structures. The present study is in the direction discussed above. Structures acquire asymmetry due to several reasons. Asymmetry in structures makes analysis of the seismic behaviour complicated. Seismic demand in peripheral elements is enhanced. Uniformity in load distribution gets disturbed. The paper first concentrates in understanding the complex behaviour of structure under asymmetric form. Then a simplified nonlinear pushover analysis has been used to find structural descriptors required in seismic vulnerability assessment. Deformation demand for different story for low-medium rise framed building has been found. Seismic load has been distributed in stories using triangular form. Then, force on frame has been distributed as per the distance from the center of rigidity and stiffness of the frame. Results have been produced in form of structural descriptors and eccentricity. The relationship with the damage is then established with eccentricity. The results are indicative of seismic vulnerability of asymmetric structure. The method proposed is an approximate method and the findings should be subjected to detailed evaluation and validation. The paper provides a simplified conceptual base to deal with the, otherwise, complicated analysis.