A Comparison of Wind Loads on Circular Bins, Silos and Tanks

Cylindrical structures -such as grain storage silos, liquid storage tanks and other bulk storage bins - have been widely used for industrial facilities. Wind load design requirements in the current ASCE 7 are lacking for such structures. It has been found that the determinations of wind loads for tanks varies in US industrial standards such as API 650, API 620, AWWA D100, AWWA D103 and NFPA22. The design requirements or approaches are defined in different ways in other standards such as those for Australia and New Zealand (AS/NZS1170.2) and India (IS875 part 3). Detailed wind tunnel tests of such structures in Australia started in the 1980s. Results indicated that the distributions of wind pressures on the walls and roofs of silos and circular tanks are different from those on regular buildings and are functions of aspect ratios (height to diameter), roof slopes and tank spacings. In this study, wind tunnel test results and design provisions from the Australian Standard for wind loading (AS/NZS 1170.2) are reviewed. A proposed codification for ASCE 7 is made. Comparison of wind loads using AS/NZS 1170.2, the proposed ASCE 7 procedure, and those in IS 875 part 3, API 650, API 620, AWWA D100, AWWA D103 and NFPA22 are included.