上承式钢桁拱桥面内极限承载力分析

In-plane ultimate bearing capacity analysis of deck-type steel braced arch bridge

为研究大跨度上承式钢桁拱桥在面内荷载作用下的非线性结构行为及极限承载力的主要影响因素,采用纤维模型法推导了计算材料非线性梁单元刚度矩阵的公式和确定单元截面中性轴的方程,分析了某上承式大跨度钢桁拱桥加载全过程的塑性区发展和应力重分布情况,探讨了几何非线性、拱上建筑联合作用、施工方法、布载方式对钢桁拱桥极限承载力的影响。发现几何非线性与拱上建筑联合作用对拱肋最大应力的影响较小,影响程度不超过6%,布载方式与施工方法对大跨度钢桁拱桥的极限承载能力有较大影响。

In order to study the nonlinear behavior and influence factors of ultimate bearing capacity for long-span deck-type steel braced arch bridge subjected to in-plane loads, the element stiffness formulas of material nonlinear beam were derived by fibre model method, the equations used to locate element neutral position were determined, the plastic region evolution and stress redistribution of the bridge during entire loading course were analyzed, and the effects of geometrical nonlinear, interaction between arch rib and deck, construction method, loading condition for the bridge were discussed. Analysis result shows that the effects of geometrical nonlinear, interaction between arch rib and deck on the maximum stress of arch rib are less, their effect degrees are within 6%, while the influences of construction method and loading condition on ultimate bearing capacity are obvious. 2 tabs, 9 figs, 15 refs.