混凝土结构有限元计算中预应力模拟方法及比较

Prestress simulation and comparison for finite element analysis of concrete structure

介绍了钢筋混凝土结构有限元分析中模拟预应力的方法并给出相关公式。以块体结构和预应力闸墩为例,对比了不同预应力模拟方法的差异。分析结果表明:荷载法计算精度受预应力筋矢跨比的影响,当矢跨比较大时会有较大误差;节点力法能够模拟任何曲率的预应力筋作用,网格划分合理时计算结果与考虑张拉过程的实体力筋法一致;对于非杆系预应力混凝土结构,需考虑混凝土开裂时应采用实体力筋法,否则可采用节点力法;采用实体力筋法模拟预应力作用时,是否考虑张拉过程对锚固端附近的混凝土压应力影响较大,对其它部位影响不明显。

Different simulation methods of pre- stress in FEM of reinforced structure are introduced and the relevant formulas are given,a block structure and a pre- stressed pier are taken as examples to compare the differences of these simulations. The analysis shows that the accuracy of loading method is affected by rise- span- ratio of the pre- stressed steel tendons and the error is large when the rise- span- ratio is large. Steel tendons with any curvature can be simulated by nodal force method and if the mesh is reasonably arranged,the result is approximately the same as the entitative rebar method that considers the stretching process. The entitative rebar method should be adopted if post- cracking behavior of mass concrete structures must be taken into consideration; otherwise,the nodal force method should be adopted. For entitative rebar method,whether the stretching process is considered or not has great influence on the concrete compressive stress near the anchor part but little effect on other area.