组合梁斜拉桥主梁虚拟双层梁模型

Virtual double-layerbeam element model of main beam of composite beam cable-stayed bridge

关键词:  组合梁  斜拉桥  收缩徐变  有限元  虚拟双层梁单元

Key words:  composite girder  cable-stayed bridge  shrinkage and creep  finite element  virtual double-layer beam element

摘要:

为准确模拟钢混组合斜拉桥混凝土桥面板和钢主梁的相互作用和二者之间因混凝土收缩徐变而导致的内力重分配,首先根据组合截面的内力分配特点和基于混凝土收缩徐变的增量递推算法开发了一种连续组合的新型组合梁单元-虚拟双层梁单元,然后采用三跨连续梁和赤壁长江公路大桥工程对该新型单元进行了验证分析和工程应用,并与工程常用的实际双层梁单元进行了比较研究。结果表明:虚拟双层梁模型计算结果与实测数据吻合较好,且相较于实际双层梁模型,单元数量可减少约67%,计算速度提高约40%。该新型单元既具有较高的计算精度又能够减少主梁单元数量,实现了钢梁与桥面板界面之间的连续组合,不仅能精确模拟混凝土桥面板的收缩徐变效应,还可模拟钢梁与桥面板的分阶段施工过程,为组合结构提供了一种精度较高的改进钢混组合梁模拟方法。

Abstract:

In order to accurately simulate the interaction between concrete deck slabs and steel girders of steel-concrete cable-stayed bridges and the redistribution of internal forces between the two due to the shrinkage and creep of concrete, according to the internal force distribution characteristics of the composite cross-section and the concrete shrinkage and creep recursive algorithm, a new type of continuous composite girder virtual double-layer beam element was developed. Then the new element was validated and analyzed by using three-span continuous girders and the Chibi Yangtze River Highway Bridge project, with a comparative study conducted against the actual double-layer element commonly used in engineering. The results show that the calculation results of the virtual double-layer beam model are in good agreement with the measured data, and the number of elements can be reduced by about 67% and the calculation speed can be improved by about 40% compared with the actual double-layer model. The new element exhibits high computational accuracy while significantly reducing main girder elements count. It realizes the continuous composition between the interface of steel girder and bridge deck, accurately simulates the shrinkage and creep effects of concrete bridge deck, and also simulates the construction process of steel girder and bridge deck in stages, which provides an improved steel-concrete composite beam simulation method of high accuracy for the composite structure.