有多条轴对称焊接凹陷的钢圆柱薄壳在内压力和轴压力共同作用下的强度

Strength of internally pressurized axially compressed steel thin cylindrical shell with multiple weld depressions

钢筒仓中圆柱薄壳承受内压力和轴压力共同作用:在轴压和低内压作用下,壳可发生弹性失稳;在轴压和高内压作用下,壳可发生塑性破坏.内压轴压共同作用下的圆柱薄壳对几何缺陷比较敏感:单条轴对称焊接凹陷可使壳的承载力降低;而多条轴对称凹陷由于相邻凹陷的相互作用,可使壳的强度进一步降低;对于小间距的凹陷,这种相互作用更为明显.本文首次对有多条小间距轴对称凹陷轴压圆柱薄壳的整体结构在不同水平内压作用下的强度进行了有限元分析,并将计算结果与欧洲规范EC3的设计曲线进行比较,对EC3的设计曲线提出了修改意见,从而达到安全设计的目的.

Thin cylindrical shells in steel silos are subject to combined action of internal pressure and axial compression: at low levels of internal pressure, an axially compressed shell may fail by elastic buckling; at high levels of internal pressure, the axially compressed cylinder fails by plastic collapse. Internally pressurized axially compressed thin cylindrical shells are fairly sensitive to geometric imperfections on shell walls: single axisymmetric weld depression may lead to reduction in load-carrying capacity of shells; multiple axisymmetric weld depressions could further reduce shell strength because of interaction of adjacent weld depressions; for small spacing weld depressions, this interaction effect is even marked. This paper presents the results of the first ever study on strength of an internally pressurized axially compressed complete cylindrical shell with multiple small spacing weld depressions using FEM. A comparison of the numerical results with EC3 recommendations found that EC3 gives rather unsafe predictions. Modifications were therefore made to EC3 design curves to achieve a safe design.