Study On Buckling Behavior Of Extensively Welded Thin Cylindrical Steel Shells Subject To Wind Loads And Eccentric Discharge Pressures

Steel silos are widely used in the field of production，generally consisting of conicalroof, cylindrical shell, conical hoper and some other parts. Buckling behavior of thecylindrical shell is often the controlling factor on the silo’s designing. Large circularsteel silos are often fabricated from joining a great number of rolled panels with manyshort meridional welds and continuous circumferential welds. This manufacturingprocess brings about circumferential axisymmetric depressed and meridional wobblydepressed，and exists relevant residual stress field. How to consider the effect ofinitial geometrical imperfection and residual stress field on steel shells is a hotspot onresearch. Currently, practical engineering happen to the non-uniform pressure, sowind loads and eccentric discharge pressures were chosen. The primary investigationsand achievements are as follows:(1) Considering the effect of initial geometrical imperfections and residual stresses,three methods of simulating welds were introduced and analyzed. To get theiradvantages and disadvantages. Studies have shown that the trapezoidal strain fieldmethod simulating initial geometrical imperfections and weld-induced residualstresses which is automatically equalized and shrinkage deformations were introducedto set up FE models. This method was proved to simulate welds well.(2) Considering trapezoidal strain field, firstly linear bifurcation analysis wasapplied to investigate the buckling behavior of perfect shells subject to wind loads andeccentric discharge pressures. We can conclude that: The buckling failure ofcylindrical shells occurs at the windward side when the cylindrical shells subject towind loads, because of non-uniform wind distribution；the buckling failure ofcylindrical shells occurs at the bottom of the cylindrical shell, with local fold failurewhen subject to eccentric discharge pressures, because of combined action of frictionforce, horizontal pressure and patch load.(3) Considering the interaction of geometrically and materially nonlinear, we didsome research on the buckling behavior of the two cylindrical shells includingcircumferential welds, meridional welds,cross welds and pattern welds,one of whichcontains weld-induced residual stresses and initial geometrical imperfection, the other only contains weld-induced residual stresses, when subjecting to wind loadsand eccentric discharge pressures. Comparing with these two results, we can figureout: steel cylindrical shells are sensitive to initial geometrical imperfection, especiallyshells with pattern welds. Each type of the welds can reduce the buckling critical loadof thin cylindrical shells. Reducing range depend on the type of the welds;circumferential weld-induced residual stresses and meridional weld-induced residualstresses have a beneficial effect on the shells buckling critical load, which canincrease the buckling critical load within a narrow range, so designers can neglect theexistence of residual stresses in practical engineering.(4) Three cylinders with real geometric imperfections were conducted by linearbifurcation analysis and geometrically and materially nonlinearity analysis. We canfigure out: the resulted buckling critical load of cylinders subject to wind loads withreal imperfections were scattered, indicating that the imperfections in real structureshave a complicated form.