COLLAPSE CAPACITY ASSESSMENT OFREGULAR TALL BUILDINGS UNDER PULSE LIKE NEAR FIELD GROUND MOTIONS

Structural response to near fault ground motions has received significant attention in recent years. Such ground motions are different from ordinary ones and are characterized by a large, long period, velocity pulse caused by the forward directivity. These velocity pulses could potentially impose sever demands on structures and increase their risk of seismic collapse. The situation could even be worse for tall buildings with fundamental periods close to the period of the velocity pulses, and requires special consideration in design process. Besides, Prediction of seismic-induced collapse potential of structures has been among the main concerns in Performance Based Earthquake Engineering (PBEE). The results could be used as an important measure in designing new structures, or evaluating the seismic performance of existing ones. Not surprisingly, much effort has been made in accurate prediction of collapse capacity of structures due to its importance in estimation of the human and monetary losses during and after an earthquake episode.Collapse assesment of structure under near fault directivity excitation shows a higher value than expcted by the code which is 1% in 50 years but in the the case of the farfield suites the resualt are almost consistent with thedesign collpase level defined by the code.