Seismic Behaviour of Reinforced Concrete Buildings with Moment Resisting Frames and Frames with Structural Walls Subjected to Near and Far-Fault Ground Motions

Abstract

One of the significant causes of life loss during an earthquake is the collapse of structures in the near-fault regions. Broadly, two sets of parameters affect the structural response, namely: (i) characteristics of structures, like configuration, stiffness, strength, and ductility, and (ii) characteristics of ground motions. Usually, the former are dependent on the latter. But the latter is derived independently by geologists, seismo-tectonists, seismologists, geotechnical engineers and structural engineers. Often, the considered seismic hazard has uncertainties arising from the way strong ground motion is considered in the near-fault regions. To understand and quantify the hazard in the near-fault regions, the ground motions characteristics are examined of the strong motion records of 1999 Chi-Chi, Taiwan earthquake. It is observed that the ground motions in the near-fault region exhibit higher PGA values on the hanging wall side as compared to the footwall side. Further, the behaviours of two reinforced concrete buildings with moment resisting frames of five and ten storeys are studied when subjected to two types of horizontal near-fault ground motions with and without velocity pulse. The responses observed and the damage caused in the moment frame buildings owing to these nearfault ground motions are identified. It is observed that the near-fault ground motions with pulse induce higher drift demands compared to those without pulse and far-fault ground motions. Also, the response of the structure subjected to near-fault ground motion with pulse indicate the impulsive action that requires a revised mitigation strategy other than the conventional earthquake resistant design procedures. Inclusion of a structural wall is identified as a simple solution to control the damage arising from near-fault ground motion effects. The maximum drift demand on the structures with structural walls with SPD of 2.75%, 3.75% and 9% are studied and improved performance is observed as the structural plan density of structural walls is increased.