预应力钢桁架结构分析中的摩擦滑移索单元

为精确模拟预应力钢桁架中连续长索在支撑点的滑动,本文创建了一种考虑摩擦力影响的新单元。被称为摩擦滑移索单元的新单元有三个节点,中间节点为支撑点。本文首先利用弹性悬链线的解析解,建立了弹性悬链线单元,并推导了单元两端点的张拉刚度。摩擦滑移索单元由两个弹性悬链线单元组合而成,根据支撑点处索的滑动方向、索力差、滑动摩擦力和滑移刚度调整两索段的原长,使支撑点两侧的索力满足给定的摩擦关系。算例验证了新单元算法的正确性和高效性,对设计的预应力钢桁架的分析,显示了张拉过程中及使用荷载作用下新单元在结构分析中的应用。新单元可直接用于常规的有限元分析,研究在工作状态或施工中存在连续长索滑移的索结构。

Friction sliding cable element for structural analysis of prestressed steel truss

To simulate the sliding of continuous cable at supports in finite element analysis of prestressed steel truss,one new element taking friction into consideration is developed.Friction sliding cable element is called to this new three-node element,which takes the support as the middle node.Based on the analytical solutions of elastic catenary,elastic catenary element was developed,and the tension stiffness at two ends were derived firstly.Friction sliding cable element is composed of two elastic catenary elements,and its two tensions at middle node satisfy the given friction relation by apportioning the unstrained cable length of the new element to the two cable segment,based on the sliding direction,difference of tensions,friction force and sliding stiffness at the middle node.Examples proved the correctness and effectiveness of the arithmetic,analysis of the designed prestressed steel truss showed its usages in structural analysis during tension and in service.This new element can be incorporated into conventional finite element analysis schemes,to analysis the cable structures with sliding cable in service or under construction.