大跨度张弦式管梁研究

大跨度预应力张弦式管梁是运输管道跨越江河或沟堑的一种新型结构形式，其跨度可达100。150m。以一榀100m跨预应力张弦式管梁为原型，设计了1：15缩尺模型，在国内首次开展了张弦式管梁在预应力张拉阶段、正常使用阶段以及承载力极限阶段的受力全过程试验研究。基于ANSYS对试验全过程进行了非线性有限元模拟，并结合一致缺陷模态法与柱面弧长法，进行了同时考虑初始几何缺陷与几何非线性的屈曲分析。试验研究与有限元分析表明：半跨荷载对预应力张弦式管梁较为不利，结构整体变形与上弦应力增长较为迅速；结构对平面外的几何缺陷较为敏感，半跨荷载下的屈曲临界荷载较全跨荷载作用时稍低；结构具有可靠的稳定性与较大的安全储备，极限承载力达设计荷载的2．68倍；有限元计算值与试验结果吻合良好，表明本文采用的非线性有限元分析方法能较好地实现对预应力张弦式管梁受力全过程的模拟。最后，基于瑞利一里兹法推导了预应力张弦式管梁在弹性与弹塑性状态下的变形与内力计算公式。

Study on long span tensioned pipe beam

The long-span prestressed tension-string pipe beam is a new type of structure for transportation pipelines crossing rivers or trenches, with a span of up to 100. 150m. Taking a 100m span prestressed tensioned string pipe beam as prototype, a 1:15 scale model is designed, and the whole process of stress testing of the tensioned string pipe beam in the prestressed tension stage, the normal use stage and the ultimate bearing capacity stage is carried out for the first time in China. The nonlinear finite element simulation of the whole test process is carried out based on ANSYS, and combined with the uniform defect mode method and the cylindrical arc length method, the buckling analysis considering both the initial geometric defects and geometric nonlinearity is carried out. The experimental study and finite element analysis show that the half-span load is unfavorable to the prestressed tension-string pipe beam, and the overall deformation and upper string stress of the structure increase rapidly. The structure is more sensitive to out-of-plane geometric defects, and the critical buckling load under half-span load is slightly lower than that under full span load. The structure has reliable stability and large safety reserve, and the ultimate bearing capacity is 2.68 times of the design load. The calculated results of the finite element method agree well with the experimental results, which shows that the nonlinear finite element method used in this paper can simulate the whole process of the stress of the prestressed tension-string pipe beam. Finally, based on Rayleigh-Ritz method, the calculation formulas of deformation and internal force of prestressed tension-string pipe beam under elastic and elastoplastic conditions are derived.