柔性组合结构的大挠度非线性有限元分析

LARGE DEFLECTION NONLINEAR FINITE ELEMENT ANALYSIS OF FLEXIBLE COMPOUNDED STRUCTURE

本文应用预应力柔性索的非线性有限元模型,用折算弹性模量考虑索初始垂度的影响,引入主一从控制原理来克服柔性元素和刚性元素共同作用时易产生的方程病态,在结构变位后的基础上建立平衡方程,采用带有动坐标的刚度矩阵迭代法,分析了斜拉桥、悬索桥等柔性组合结构的大挠度问题。应用本文方法,已经成功地分析了多座斜拉桥实际结构。对于一般柔性组合结构,经过二至六次迭代即可达到相当的精度。

A nonlinear finite element model is presented for the pres-tressed flexible cable which takes into account the effect of initial deflection on stiffness using a conversion modulus of elasticity. To overcome the ill-condition of stiffness matrix caused by cooperation of flexible and stiff elements, Master—Slave relations between the modal displacements are introduced. And then a new stiffness matrix iteration method with movable nodal coordinates and Maste-Slave relations is developed to analyse flexible compounded structures such as cable-stayed bridges, suspension bridges etc., in which the equilibrium equations set up for the structure subjected to deflection. The method developed in this paper has been successfully applied to analyse many cable-stayed bridge structures in practice. Usually a satisfactory accurancy can be obtained after 2 to 6 iterations.