Assessment of Seismic Behavior of Framed Tubesand Bundled Tubes in Near-Field Zones

The previous studies on engineering seismology show that the wave-like features exist intime history of powerful near-field earthquake records. The Physical characteristics ofthis type of earthquake records can be explained based on the forward directivity as wellas filing step effects which are recorded in near fault quaked zones. It should be notedthat the PGA and PGV parameters related to near-field strong motions are larger thanthose of far-field records. The existing pulse features in velocity time history of a nearfieldrecord are recognized based on various types of rupture directivity effects. Thisphenomenon is created based on the negligible difference between the velocity of ruptureprocess in fault mechanism and the shear wave propagation velocity during a strongearthquake. The existence of high-amplitude and long period velocity pulses in timehistory of near-field records impresses the configuration and the characteristics ofstructural dynamic behavior. Hence, under the effects of near-field records, there existsthe relative difference with moderate variation amplitude between the correspondingresponse parameters of flexural framed tube and flexural bundled tube structures. Thestudies indicate that the response parameters of both flexural framed tube and flexuralbundled tube structural skeletons which designed based on the criterion of weak beamand strong column, would display a more non-linear specific behavior subjected to strongnear-field records which contain powerful velocity pulses. This article includes acollection of studying non-linear dynamic response parameters of steel structures withflexural framed tube and flexural bundled tube skeletal systems under three componentnear-field records. The time history of the selected earthquake records contains variousfigurations of ground velocity pulses. Finally it is observed that flexural framed tubes andflexural bundled tubes can satisfy the Iranian design code restrictions for story drift.