Ground elevated Reinforced Concrete (RC) silo is a popular device in material handling plant and food grain processing plants to supply it throughout the year. When the structure is analyzed under wind load, the distribution of internal forces does not follow the typical pattern expected from the beam bending theory due to highly non-axisymmetric variation of wind pressure along the circular periphery considering the silo as a thin-walled tubular structure. The silo wall deforms considerably in its cross-section due to ovalization instability. Circular silo having ratio of height of wall to diameter exceeding one (H/D>1) is susceptible to such deformation to greater extent. In the case of long cylindrical steel silo ring stiffeners are provided in order to reduce this ovalization effect on the silo wall due to wind loads. But in the case of a reinforced concrete silo, ring stiffeners are not provided to avoid construction hazards during slip forming. This paper presents a review of the previous investigations in connection with the same. In most of the investigations reviewed so far, distribution of wind pressure in cylindrical silo wall, pre-buckling and post-buckling analysis of steel silo under wind load are discussed. Little investigation has been found regarding the deformation pattern of wall of right circular cylindrical shell wall, in particular the one made up of reinforced cement concrete. The authors are deeply motivated to find a direction in this context through extensive review of work pertinent to the field and attempts will also be made in future for further improvement of the existing analysis of RC cylindrical silo wall under such action of wind load.

‘Bin’ or ‘bunker’ or ‘silo’ structures are used to store granular or fine material to supply it throughout the year. This type of structure is not only subjected to gravity load, but also there is an effect of lateral load in this structure. The lateral load may be wind or seismic load. When a cylindrical structure having circular cross-section is subjected to wind loading then there must be an ovalization phenomenon. There is a considerable deformation in the cross-section of the silo wall due to ovalization instability. When the height to diameter ratio is less than or equal to 1 (H/D£1), then this ovalization phenomenon does not give any severe impression to the said structure. But when this height to diameter ratio exceeds 1 (H/D>1), then this ovalization as well as deformation leads to greater extent. Due to the ovalization phenomenon, the shell wall will get deformed and this deformation is totally different as compared to the rectangular beam deformation. From the deformation point of view, we can consider the cylindrical shell as a tubular beam. To reduce this ovalization instability, ring stiffeners are used for long cylindrical steel silo; at the same time, ring stiffeners are not used for reinforced cement concrete silo just because of construction hazards during slip forming. In most of the previous investigation, we have seen that for wind loading analysis, there is a long area covered by steel cylindrical shell, whereas in the case for reinforced concrete cylindrical shell, this covered area is very less. This paper presents a review of the previous investigation related to the ovalization phenomenon of the cylindrical structures (silo, cooling tower and wind tunnel).

Structural Engineering Journal, Ground elevated silo, Cylindrical wall, Wind load, Ovalization of shell wall, Review.