Simplification of the dynamic characteristics of the wind loading on a low-rise structure

Abstract

The paper deals with the method of simplification of the dynamic characteristics of wind loading on a low-rise structure. All wind forces are dynamic in the sense that they are the effects of a continuously moving airstream and wind velocity is a complex randomly varying quantity resulting in a very complex type of loading on structures. In order to determine the effects of such a loading, laborious and lenghty calculations are required and it is extremely difficult to specify the wind loading easily. In this paper it is shown that fluctuations in the wind velocity have little effect on the response of a steel framed low-rise structure—a Dutch Barn having a natural frequency of 8 Hz. From the examination of the theoretical deflections of the structure caused by large magnitude gusts, it was found that there was very little difference in the maximum value of deflection which resulted from the actual loading and simplified loading in both cases of triangular gusts and rectangular sharp-edged gust. A single sharp-edged gust is recommended on the basis of a variation of ± Vav/4 about the mean ‘five second gust’ and having a gradient of 220 km/hr per second for the low-rise building structures having a natural frequency of 8 Hz for design purposes.