轴压套管构件的典型破坏模式与极限承载力

Typical failure mode and ultimate bearing capacity of sleeved compression member under axial compression

建立了轴向压力作用下两端铰接钢套管构件的非线性有限元分析模型.通过套管构件的非线性有限元分析,得到内核弯矩分布随轴向压力增大的变化规律,并得出套管构件的破坏机理.分析了内核长细比、内核外伸长度、套管-内核间隙及套管-内核壁厚比等参数对套管构件极限承载力因子的影响,并采用多项式函数拟合得到套管构件极限承载力的实用计算公式.结果表明,轴向压力增大,内核弯矩最大截面逐渐向内核端部移动,在轴向压力与弯矩的共同作用下,内核端部附近截面达到全截面塑性,导致套管构件承载力下降.随内核长细比的增大以及内核外伸长度及套管-内核间隙的减小,套管构件极限承载力因子逐渐增加.

The nonlinear finite element analysis model was established for the pinned-end steel sleeved compression member under axial compression. By the nonlinear finite element analysis of the sleeved compression members, the changing trend of the core moment distribution was obtained with the increase of the axial load, and the failure mechanism of the sleeved compression member was explained. The effects of the core slenderness ratio, the core protrusion length above sleeve, the gap between the sleeve and core, and the wall thickness ratio of the sleeve to core on the ultimate bearing capacity factor of the sleeved compression member were analyzed. The practical calculation formula for the ultimate bearing capacity of the sleeved compression member was fitted by the polynomial functions. The results show that the core section with the maximum moment shifts gradually to the end with the increase of the axial load. The ultimate bearing capacity of the sleeved compression member decreases once the core section near the end subjected to combined axial force and moment achieves full-section plasticity. The ultimate bearing capacity factor of the sleeved compression member increases with the increase of the core slenderness ratio and the decrease of the core protrusion length above sleeve and the gap between the sleeve and the core.