Drift estimates in frame buildings subjected to near-fault ground motions

A simple procedure to estimate the local displacement demands in regular frame-type structures that respond in elastic limits is described. Given the spectral displacement and beam-to-column stiffness ratio, the procedure estimates the maximum ground story and maximum interstory drifts along the height of the structure. A total of 145 near-fault ground motions recorded on dense-to-firm soil sites are used for the evaluation of the procedure. The approximate drift demands computed from this procedure and the exact results from 27,550 response history analyses are used for calculating the error statistics. The calculations show that the procedure can be used with confidence for frames with fundamental periods between 0.3 and 1.5 s when they are subjected to near-fault records without pulse. The approximations are in good agreement with the exact response history results of near-fault records with pulse when the fundamental period to pulse period ratio is less than 1.5. The performance of the new procedure is also compared with other approximate methods that are employed for similar purposes. The method can be useful for preliminary design of new structures or rapid assessment of existing buildings.