09-10-2014, 03:51 PM
A state-of-the-art review of the gust factor method for the alongwind response of structure has presented. The provisions of this method as recommended by the Indian Standard Code, IS:875 (Part 3)-1987, have been critically examined. It is shown that the codal values may be too conservative as those are based on the assumption of wind energy spectra being independent of height above the ground. Also, the assumption of perfect correlation between the velocities on-the windward and leeward faces of the building is shown to give conservative estimates. It has been shown that the use of more realistic logarithmic law for the mean wind velocity profile leads to even lower gust factors. Further, the assumptions of first mode shape being linear and that of the complete dominance of the first mode in the dynamic wind response of buildings have been justified.