Considering rupture directivity effects,which structures should be named ‘long‐period buildings’?

Recorded accelerograms in the regions near active faults may have specific characteristics that inclusion of their effects on the response of structures is necessary. Of particular importance are permanent displacement, i.e. fling‐step, rupture directivity pulses and high‐frequency content. Several researchers have focused on the effects of rupture directivity pulses on response of structures. They have shown that long‐period structures are severely affected by these types of excitations. However, in near‐fault regions, the question ‘which building structures are long period?’ has not been clearly and quantitatively answered. In this paper, responses of 10‐, 20‐, 30‐ and 40‐story steel structures designed based on Uniform Building Code 1997 regulations are investigated under artificial pulses produced by directivity effects. It is shown that, considering rupture directivity effects, a long‐period structure is the one that has a first‐mode period–to–pulse period ratio greater than about 0.44. Furthermore, the effects of variations in the period of the near‐fault velocity pulses on the characteristics of inelastic response of structures are examined. Consequently, analysis of the structures experiencing actual near‐fault records indicates that the pattern of response spectrum obtained from artificial pulses presents the behavior of the structure under real near‐fault earthquakes rather accurately. Copyright © 2010 John Wiley & Sons, Ltd.