Effect of strength deterioration on inelastic seismic torsional behaviour of asymmetric RC buildings

The paper presents a limited study on the inelastic torsional behaviour of reinforced concrete (RC) asymmetric buildings using idealized one-storey models. The strength deterioration characteristics of reinforced concrete members is included in the hysteresis rules of the load-resisting elements in this study. It is observed that these characteristics may largely magnify the displacement and ductility demand in structural elements due to successive localized unsymmetric yielding and progressive strength deterioration; resulting in continuous shifting of the centre of strength and thereby increasing strength eccentricity. This magnification effect is generally found to be increasing with the rate of strength deterioration. This effect is not recognized in numerous studies on inelastic behaviour of asymmetric buildings as these studies considered a bilinear hysteresis behaviour devoid of strength deterioration characteristics for lateral load-resisting elements; and as a consequence comparatively lower displacement and ductility demand in load-resisting elements were observed. While using the results of existing literature on inelastic seismic torsional behaviour of asymmetric buildings to predict the behaviour of RC asymmetric buildings, this limitation should seriously be considered.