Determining Cause Of Failure For Load Cells Supporting Vertical Pressure Vessels Subject To Wind Loading

Wind loads cannot be avoided during a natural disaster such as a hurricane and could affect the strength and stability of vertical pressure vessels during exposure. Vertical pressure vessels cater to large wind loads; therefore, it is imperative to study the effect of additional loading on the structures. In this study, three pressure vessels with volumes of 50 CuFt, 200 CuFt, and 1100 CuFt, supported by three equidistant load cells under their legs are individually analyzed to determine von mises stress to estimate yield failure criteria. Two load rating criteria, maximum load capacity and water-filled condition (critical condition) are utilized for static analysis to determine the strength of load cells and to calculate safety factors. Solidworks and Ansys workbench 19.1 software were utilized to generate and compare the results of each analysis. The analysis shows that the load cells are sustainable for both criteria with the factor of safety of 1.95, 1.22, and 1.30 for the critical condition for the 50 CuFt, 200 CuFt, and 1100 CuFt pressure vessels respectively. Under normal conditions, the weight of the pressure vessel is unevenly distributed as it has been observed that there are greater loads (and deformations) in the two load cells approximately under the manway apparatus. This is extra important in the 50 CuFt vessel because the centerline of the manway does not lie on the angle bisector of the two nearest load cells. Once a constant, steady wind load is introduced, the vessel will not topple as the attached load cell assembly underneath is anchored to concrete. The only movement possible is vertical deflection in the load cell resulting in greater uneven load distribution on the load cells, this scenario leads to inaccurate measurement when the load exerted on the load cell exceeds the maximum load capacity. Varying steady wind speed conditions with a maximum wind velocity of 120 mph are calculated to determine the stability of the system. The empty pressure vessel condition under wind loading resulted in the stress at one load cell to be zero at approximately 71 mph, 83mph, and 88mph for 50 CuFt, 200 CuFt, and 1100 CuFt respectively. Further, stability and the stiffness of the pressure vessels with load cells were analyzed using dynamic analysis to determine the fundamental natural frequencies of the vessels and compared to the vortex shedding frequencies calculated at various wind velocities to investigate the potential of resonance when the vessel is subjected to steady wind conditions. Results indicate that the 50 CuFt model can be subjected to resonance conditions at an approximately constant velocity as low as 25 mph