轴压套管构件静力稳定的理论与试验研究

针对轴压套管构件，理论研究了初弯曲内核与柔性套筒未接触、点接触、线接触、线接触屈曲后等变形过程，利用小挠度二阶平衡微分方程推导了内核及套筒挠度、弯矩、剪力、接触力等物理量的计算公式；进行了两类套管构件的试验研究。理论与试验的对比研究表明:1) 内核与套筒的刚度比小于0.005时，内核可以由低阶屈曲模态变形到高阶屈曲模态；内核与套筒的刚度比大于0.005时，内核将与套筒一起发生侧向失稳破坏；2) 套筒较刚、内核长细比较小、内核-套筒净间隙较大，不利于显著提高内核的轴压承载力；内核外伸套筒部位是薄弱部位，为避免该部位的局部屈曲，需要减小该部位的长度，并对其予以加强。

THEORETICAL AND EXPERIMENTAL INVESTIGATIONS ON THE STATIC STABILITY OF A SLEEVED COLUMN

The deformation processes of the non-contact, point-contact, line-contact, post-buckling of line-contact, etc., between the flexible sleeve and the axially compressed inner core with initial deflections in a sleeved column, are researched theoretically. Expressions of the deflection, moment, shear and contact reaction of the inner core and the sleeve are derived, adopting the second order differential equilibrium equations of a small deflection. Two types of sleeved columns are experimentally studied. The following results can be obtained: 1) If the stiffness ratio between the inner core and the sleeve is smaller than 0.005, the inner core snaps from the low order mode to the higher order mode; if the stiffness ratio is larger than 0.005, the inner core fails together with the sleeve due to lateral buckling; 2) Stiff sleeve, small slenderness ratio of the inner core and large net clearance between the inner core and the sleeve exert adverse effects on the remarkable improvement of inner core's bearing capacity. The parts of the inner core outside the sleeve are the most vulnerable; their lengths must be small and the parts must be strengthened to avoid the local buckling of the inner core.