Assessment of Near-Fault Ground Motion Effects on the Fragility Curves of Tall Steel Moment Resisting Frames

Nowadays it is common to use the fragility curves in probabilistic methods to determine the collapse probability resulting from an earthquake. The uncertainties exist in intensity and frequency content of the earthquake records are considered as the most effective parameters in developing the fragility curves. The pulse-type records reported in the near-fault regions might lead to the major damages in the structures having moderate and long periods since response spectra of near-fault ground motions within the long period range are different from those of the far-fault ground motions. In the present study, the influence of this type of earthquake records on the fragility curves of the steel special moment resisting frames, SMRFs, was examined. The results indicated that the median value of the collapse capacity (i.e.ŜCt Parameter, which defines the earthquake intensity leading to the collapse of the structure in half-set of the chosen records) due to near-fault ground motions was 76% that of the far-fault records for the ten-story example SMRF.