【摘要】 基于洪奇沥水道特大桥主跨为2×360 m的大跨度下承式钢桁架柔性拱桥建立有限元模型,考虑结构的几何初始偏位、几何和材料的双重非线性以及温度因素,进行施工阶段和运营阶段的稳定性分析。结果表明:该桥失稳形式为拱肋整体面内失稳;仅考虑几何非线性时,结构的稳定系数降低10.53%;考虑几何和材料双重非线性时,稳定系数降低73.9%,并随几何初始偏位的增大进一步减小;拱肋施加1/3 000—1/1 000计算跨径的初始横向位移时,结构的稳定系数降低0.38%—5.66%;钢桁梁受材料非线性影响显著,拱肋次之,纵横梁最小;温度变化对结构的稳定性影响较小,当温度上升60℃时,结构的稳定系数增加0.72%,当温度下降15℃时,结构的稳定系数降低0.19%。各种因素下最不利稳定系数为2.39,桥梁结构总体稳定性良好。更多还原

【Abstract】 The finite element model was established based on a super large bridge on Hongqili water channel, which was a long-span through bridge with steel truss, flexible arch and the main span of 2×360 m. Stability analyses of both the construction and service stages were carried out considering such factors as the geometric initial deviation of structure, the double-nonlinearity of geometry and material as well as temperature. Results show that the instability forms of the bridge are the instability of arch ribs in the whole plane. When geometric nonlinearity is considered only, the stability coefficient of the structure is reduced by 10.53%. When the double-nonlinearity of geometry and material is considered, the stability coefficient is decreased by 73.9% and is further decreased with the increase of geometric initial deviation. When the initial transverse displacement of 1/3 000 to 1/1 000 of the calculated span is applied to arch rib, the stability coefficient of the structure will be reduced by 0.38% to 5.66%. The steel truss girders are significantly influenced by material nonlinearity, followed by arch ribs, the longitudinal and transverse beams the minimum. Temperature change has little influence on the stability of the structure. The stability coefficient of the structure increases by 0.72% when the temperature rises 60 ℃. The stability coefficient of the structure decreases by 0.19% when the temperature drops 15 ℃. Under various factors, the most unfavorable stability coefficient is 2.39 and the overall stability of bridge structure is good.更多还原