SEISMIC FINITE ELEMENT ANALYSIS OF IRREGULAR REINFORCED CONCRETE BUILDINGS IN ELEVATION

Near field ground motions are different from ordinary ground motions in that they often contain strong coherent dynamic long period pulses and permanent ground displacements. The dynamic motions are dominated by a large long period pulse of motion that occurs on the horizontal component perpendicular to the strike of the fault, caused by rupture directivity effects. This paper addresses multistorey reinforced concrete buildings, irregular in elevation under near field earthquakes. Two twelve-story buildings with two and four large setbacks in the upper floors respectively, as well as a third one, regular in elevation, have been designed to the provisions of ACI 318-2005 for the high (DCH) and medium (DCM) ductility classes, and the same peak ground acceleration (PGA) and material characteristics. All buildings have been subjected to inelastic dynamic time-history analysis for selected input motions. The assessment of the seismic performance is based on both global and local criteria. It is concluded that irregular buildings demonstrate poor seismic performance in terms of ductility and energy dissipation capacity during severe seismic events. As expected, DCM buildings are found to be stronger and less ductile than the corresponding DCH ones .

کلیدواژه ها:

reinforced concrete buildings ، irregularity in elevation ، near field ، setbacks ، seismic performance ، time-history analysis