Stability of Aboveground Open-Top Tanks Subjected to Wind Loading: Static and Dynamic Analyses

Boundary layer wind tunnel tests have shown that when open-top storage tanks are subjected to wind loading, an internal inward pressure is generated, which is a phenomenon not observed when close-top tanks are examined. This internal pressure is accounted for in both European and Australian/New Zealand design documents, but may not be sufficiently addressed in North American design documents such as ASCE-7, API 650 and AWWA D-100. To investigate the adequacy of these documents, above ground open-top steel tanks with a wide range of height to diameter ratios (H/D), were examined. The tanks were subjected to multiple finite element analyses including a linear bifurcation analysis, a static geometric nonlinear analysis with imperfections, and an explicit dynamic analysis. It was found that the internal pressure significantly affected the buckling capacity of a tank, and revisions of the structural stability and wind girder design guidelines were suggested for North American design documents. Resonance was not observed in the analyses when dynamic effects were considered, and the differences between the result of the dynamic and static analyses for broad tanks (H/D < 1.0) were minor. Therefore, it was concluded that a static analysis is adequate for a practical tank design.

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