ALONG WIND ANALYSIS OF REINFORCED CONCRETE CHIMNEYS

Abstract

Along wind analysis of tall reinforced concrete (RC) chimneys by random vibration approach and Codal methods of India (IS 4998 (part 1)), America (ACI 307) and Australia (AS/NZS 1170.2) are presented in this paper. For the analysis based on random vibration approach, the RC chimney is modeled as multi-degree-of freedom system subjected to static load due to mean component of wind velocity and dynamic load due to fluctuating component of velocity. The fluctuating component of wind velocity at a point is considered as temporal random process. Next, the codal procedures for along-wind analysis of tall RC chimneys from Indian, American and Australian codes are reviewed. Four RC chimneys are analyzed using these methods to obtain their responses. It is found that the codal methods of along-wind analysis are simplistic, are not equipped to estimate the deflection of the chimneys and producing varied results. The simplifying assumptions used in these codes are discussed.