Development of a Simplified Damage Model for Beams Aiding Performance Based Seismic Design

Abstract

Performance based design is an emerging area in earthquake engineering in which damage modeling of structural components plays an important role in achieving the performance objectives. Past researches in damage index evaluation indicated no obvious shear dependent trends on cyclic combined shear and flexure. Paper focuses in finding a simple and realistic indicator, which gives a reliable measure of the structural damage, and use it in the design stage calculations of medium and long period structures. Experiments consisting of monotonic and cyclic tests were conducted on a variety of concrete beams. Two available models for damage indices in the literature, namely Park and Ang model and the model suggested by Rao et al. (1998), were used to predict the damage indices. A simple set of relationships connecting damage index to the failure cyclic ductility ratio, shear span to depth ratio and cyclic amplitude have been derived. The above relationships have been validated on the test data generated during the present investigation. A procedure to evaluate the demand-monotonic ductility ratio at failure corresponding to a given state of damage and the shear span to depth ratio has been developed from the proposed curves.