预应力混凝土薄壁高墩刚构桥梁极限承载力分析

Analysis of Ultimate Bearing Capacity of Pre-stressed Concrete Frame Bridge with High Piers

为解决实体单元模型在大型复杂结构极限承载力分析时计算不收敛的问题,将预应力钢绞线和钢筋作为单元中的块,利用实体退化的板单元建模模拟混凝土材料,用Ohtani-Chen多重强化模型考虑混凝土的材料非线性,采用理想弹塑性模型考虑钢筋的材料非线性,用安全拉格朗日法考虑结构的几何非线性,对混凝土裂缝采用正交模型处理。模拟计算了一简支空心板梁的加载破坏过程,与实体梁加载试验结果具有良好的一致性,对一5跨连续预应力高墩刚构桥梁的极限承载力进行了计算,并与相同工程背景下采用通用ABAQUS有限元程序的分析结果进行比较。结果表明:所提方法能有效克服混凝土裂缝引起的计算不收敛现象,得到结构最终的破坏形态。

In order to overcome the calculation misconvergence in the analysis of large complicated structure＇s ultimate bearing capacity with solid element model, the wires and bars in pre-stressed structures were meshed as blocks in the element, and the concrete was simulated with solid degenerated shell element. In the analysis, perfect elasto-plastic model was adopted for reinforced bars and pre-stressed wires, while for concrete, the Ohtani-Chen multiple strengthening model was applied. Meanwhile, the Total Lagrange method was applied to calculate the geometrical nonlinearity effect,and the orthotropic crack model was applied to simulate the concrete cracks. The analysis theory was used to simulate the loading and failure process of a simple hollow board beam, which showed fair accordance with the test results. Then the bearing capacity of a typical 5 span pre-stressed concrete frame bridge with high piers was calculated and analyzed with both the geometrical nonlinearity and material nonlinearity effect considered. The calculation results were compared with that with ABAQUS. The results show that the proposed method can overcome the misconvergence in the calculation induced by the concrete cracks and the real collapse state of the structure can be derived.