滑轮在索上滑行分析的索-轮单元法

为了分析索结构中滑轮在悬索上行走及连续长索从滑轮下绕行问题，创建了一种新的单 元. 被称为索-滑轮单元的三节点新单元模拟一段索支承滑轮，滑轮的中心取为中间节点， 索的两端点为另外两节点. 基于有限元分析的基本原理，并利用处于平衡状态时单元内力之间的关系，推导了单元的算法. 这种新单元可以通过自动调整滑轮两侧索段的长度使单元处于平衡状态，从而简化了计算. 算例证明了新单元的算法及所编制程序的正确性，同时说明了它在工程中的应用. 给出了构成刚度阵的各矩阵的显式表达式. 新单元可以直接用于常规的有限元分析中，分析处于工作状态或施工中的索结构.

Cable-pulley element to analysize pulley sliding on cable

In order to analysis the cable structures with pulley sliding on the cable, or cable sliding under pulley, a new element was developed. The three node element, which is called cable-pulley, models one segment of cable supporting pulley, and takes the center of pulley as the middle node, the two ends of the cable segment as the other two nodes. The derivation was based on the foundational principles of finite element analysis, and the relation of the forces in the element at equilibrium state was used. This new element simplifies computations by automatically adjusting the cable on each side of pulley in order to maintain equilibrium. Examples proved the correctness of the derivation and the program developed by the author, and presented its practical usage. The explicit formulas of matrixes composing the stiffness are given. The element can be incorporated into conventional finite element analysis schemes, to analysis the cable structures in service or during construction.