Wind induced oscillation on a tall circular storage shell for various terrains

Abstract

The wind is an important natural phenomenon, which adversely affects different structures, such as high-rise buildings, chimneys, tanks, silos, bridges etc. The effect of wind on tall circular storage shell structures becomes critical, especially when it is in empty condition. Wind induced radial, meridional and axial stresses can cause ovalling, buckling, rupture, overturning etc. on circular storage shells. Terrain, topography, surface roughness, wind velocity, etc. are some of the important factors which influences the wind pressure distribution on circular storage shells. Also, the wind-induced oscillation may lead to structural failure of such shells. Significantly, a small number of studies are there on the effect of these factors on the aerodynamic excitation of circular storage shells. These available scopes and the importance of the studies on circular shell under aerodynamic excitation draws the attention of the present authors to investigate in this field. In the present study the authors have conducted computational fluid dynamics analysis, fluid–structure interaction analysis and modal analysis on a tall circular storage shell with slenderness ratio 4.0 considering four different terrains as per IS 875, part 3, 2015. These terrains are open terrain (terrain 1), open terrain with well scattered low to mid-rise objects (terrain 2), terrain with numerous closely spaced low and mid-rise objects (terrain 3) and terrain with closely spaced tall objects (terrain 4). The atmospheric boundary for each terrain is simulated using power law. The effect of terrain variation is assessed through the variation in the mean, and fluctuating wind pressure coefficient distribution around the circumference of the tall shell. It is observed that the mean pressure coefficients decreases and the fluctuating pressure coefficients increases in the side region of the shell, with the change in terrain conditions from terrain 1 to terrain 4. The highest and lowest pressure fluctuations are observed in the side region and leeward region, respectively. The wind-induced oscillation of the tall shell in relation to the fluctuating pressure coefficients have been assessed and the deformation of the tall storage shell for six consecutive mode shapes have been highlighted for terrain 4, where the distribution of fluctuating pressure coefficients is highest in magnitude.