Evaluation of Seismic Performance of Reinforced Concrete Buildings Using Incremental Dynamic Analysis (IDA) for Near Field Earthquakes

ABSTRACT: In the proximity of an active fault system, ground motions are significantly affected by the faulting mechanism, direction of rupture propagation relative to the site (e.g., forward directivity), as well as the possible static deformation of the ground surface associated with fling-step effects. These near-source outcomes cause most of the seismic energy from the rupture to arrive in a single coherent long-period pulse of motion. Failures of modern engineered structures observed within the near-fault region in 1994 Northridge earthquake revealed the vulnerability of existing buildings against pulse-type ground motions. Additionally, strong directivity effects during the 1999 Kocaeli, Duzce, and Chi-Chi earthquakes renewed attention on the consequences of near-fault ground motions on structures. Hence, the relevant question becomes how vulnerable is the present structure to near fault ground motions, whereas they were designed for far faults ground motions. This thesis investigates the results of illustrious characteristics of near-fault ground motions on the seismic response of three reinforced concrete structures (6-Story, 10-Story and 15-Story). The structures are designed in compliance with the ACI code specification and ground motion was scaled according to ASCE 07-05 standard to apply in nonlinear time history analysis. Preliminary design of models is carried out by using ETABS software and the nonlinear structural evaluations are carried out by using the OpenSees software. Numerical modelling carried out in this thesis showed that the reinforced concrete buildings are under large deformation requirements during the presence of velocity pulses in velocity time history. Incremental dynamic analysis (IDA) solutions revealed that considerable amount of energy is required to be wasted and reach to collapse point. Moreover, result of this study shows that the vertical pulse of ground motion can be illustrious influence on seismic response of building when it combined with horizontal pulse. Keywords: Near-fault, Reinforced concrete building, Fling step, Incremental dynamic analysis (IDA), Seismic demands. …………………………………………………………………………………………………………………………