大跨度钢管混凝土窄拱桥稳定性可靠度分析

铜瓦门大桥是一座主跨238 m、桥面宽10 m、宽跨比1/23.8的中承式钢管混凝土提篮拱桥.该桥设计采用了只由两根钢管混凝土弦杆和钢管腹杆组成的平面桁架拱肋.稳定安全性成为该桥结构设计的控制因素.首先根据钢管混凝土拱桥主要理论,在充分考虑材料性能、结构几何参数和计算模式的不定性基础上,建立了拱肋5个典型截面稳定性失效模式下的功能函数,获得了拱肋局部稳定性的可靠指标,各可靠指标均满足公路桥梁结构构件安全等级为一级的延性破坏目标可靠指标要求.然后采用与结构可靠度几何法相结合的响应面样本选取的新方法,进行了整体稳定性的可靠度研究,计算结果为平面桁架式拱肋的应用提供了理论基础,并进一步证明平面桁架式拱肋为大跨度钢管混凝土窄拱桥提供了一个有效的竞争方案.

Reliability analysis of long-span CFST narrow arch bridge's stability

Tongwamen Bridge is a 238 m span, half-through, concrete-filled steel tubular (CFST) X-type arch bridge. The width of the deck is only 10 m, yielding a width-to-span ratio of 1/23. 8. The plane truss type section rib was adopted, which was made of two CFST chords and web member system. The lateral stability is the key issue to this bridge. Firstly, based on the CFST main theory, the method for performance functions of local stability failure mode is discussed, considering material performance, structure geometrical parameter and indefinite calculation model. Five performance functions of typical arch rib are put forward for a maximum load case. According to the analytical result, the reliability meets the necessity of object reliability index, bridge structure member of highway. Secondly, the response surface method is employed to obtain the reliability index of lateral stability. The arch ribs are safe enough to keep excellent stability. The calculated result provides the foundation that the plane truss rib would be a competitive solution for a long-span, narrow, CFST arch bridge.