SUMMARY Seismic demands imposed on tall buildings are sensitive to long‐period ground motions. A source of these motions can be near‐fault effects: rupture directivity and fling step (large coseismic displacements). The potential adverse effects of near‐fault motions on structures have been attributed to rupture directivity in previous studies. However, the influence of large coseismic displacement on tall building seismic response has not been widely investigated. This study explores the influence of coseismic displacements on the nonlinear response of tall buildings. Several nonlinear time history analyses were performed to evaluate the response of a reinforced concrete tall building to coseismic displacements. The ground motions used for these analyses were recorded in the proximity of faults where large coseismic displacements have been observed. Recorded motions from the Landers earthquake (1992), Kocaeli earthquake (1999), Tohoku earthquake (2011) and Chi‐Chi earthquake (1999) were selected for this study. The results from a parametric study of the response of a single‐degree‐of‐freedom system showed that the influence of the fling on the system response is dependent on (a) the ratio of fling rise time to the fundamental period of the system and (b) the yielding resistance of the structure. At the onset of yielding, the fling step can further drive the system into very large displacements. The results from the case study indicate a significant increase on the seismic response of a tall building when the fling effect is included in the ground motions. This issue is a concern for tall buildings in regions where faults are not mapped to a great extent and near‐fault fling effect could be produced by a large magnitude earthquake. Copyright © 2011 John Wiley & Sons, Ltd.

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Summary The effects of ground motion directionality on seismic response of buildings are at the center of ongoing debate among earthquake engineering professionals and researchers. This has prompted a renewed interest to have a better understanding of directionality effects of near‐field pulse‐like ground motions on seismic response of tall buildings to further improve seismic design in this respect. In particular the prediction of the maximum displacement response along the structural axis which is called the critical displacement response. This paper presents the results from parametric studies that investigate the directionality effects on nonlinear dynamic response of simple structures and a tall building. The outcome of these analyses was the development of a method, which relies on the maximum velocity to provide a good approximation to the critical displacement response. The method developed is computationally efficient and involves less calculation than other methods. In addition, it was determined that the building responses to records rotated to fault‐normal can lead to significant underestimation of the maximum response along the structural axis, using the fault‐parallel ground motion also may lead to large response differences and smaller yet significant differences when using the maximum direction ground motion.

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