矩形截面两铰空间桁架拱平面内稳定性

In-plane stability of rectangular cross-section two hinge spatial truss arch

本文主要研究矩形截面圆钢管空间桁架圆弧拱的平面内稳定性,包括平面内一阶弹性屈曲,弹塑性稳定承载力和失稳机制的研究。首先,介绍了考虑剪切变形的一阶整体弹性屈曲荷载计算公式,并运用有限元验证了公式的适用性。其次,研究了空间桁架拱在径向均布荷载、全跨竖向均布荷载和半跨竖向均布荷载作用下的平面内稳定承载力。通过引入纯压正则化长细比和稳定系数,得到桁架拱的纯压平面内稳定曲线和设计公式,为压弯荷载作用下桁架拱的承载力设计方法的提出奠定了基础。结果表明:可以参考《钢结构设计标准》中的c类柱子曲线来评估纯压桁架拱的整体稳定性能。分析了空间桁架拱在压弯荷载作用下的破坏模式和相应的破坏机理,结果表明:破坏模式主要分为整体失稳、弦杆局部失稳和腹杆局部失稳,其中弦杆和腹杆局部失稳会显著降低拱的承载力。

This article mainly studies the in-plane stability of rectangular cross-section circular steel pipe spatialtruss arc arches, including the study of first-order elastic buckling in the plane, elastic-plastic stability bearingcapacity, and instability mechanism. Firstly, the formula of the first-order global elastic buckling load of the archconsidering shear deformation is introduced, and the applicability of the formula is verified by the finite elementmethod. Secondly, the in-plane stability bearing capacity of spatial truss arches under radial uniform load, full-span vertical uniform load, and half-span vertical uniform load is studied. The stability curve and design formula ofspatial truss arches are obtained by introducing a normalized slenderness ratio and reduction factor, which lays afoundation for the bearing capacity design method of truss arches under compression-bending load. The results showthat the global stability performance of the arch can be evaluated by referring to the c column curve in Standard fordesign of steel structures. The failure modes and mechanisms of space truss arch under the joint action of axial forceand bending moment are analyzed. The results show that the failure modes can be divided into global instability,chord local instability and transverse tube local instability, in which chord and transverse tube local instability cansignificantly reduce the bearing capacity of arch.