中文摘要：

柔性椭球（椭圆）由结构的柔度矩阵推导而得,它可通过椭球（椭圆）的形式定性地描述出荷载改变对节点位移的影响,从而评价节点对荷载作用的敏感性.本文应用柔性椭球（椭圆）评价索杆体系结构的节点敏感性以及最不利节点.为了避免求解冗繁的结构柔度矩阵,引入节点柔度矩阵的概念,在此基础上提出一种求解节点柔度矩阵的方法,从而有效求解柔性椭球（椭圆）,并编制了分析程序.

英文摘要：

The flexibility ellipsoid（ellipse） is based on the static analysis of structures and derived from the flexibility matrixes of structures.The flexibility ellipsoid describes qualitatively the influence of loading to nodal displacement,and sequentially evaluates the sensitivity of node to loading.The flexibility ellipsoid is applied in this paper to evaluate the structural sensitivity and the most un-favorable node of cable-strut structures.To avoid solving complicated flexibility matrix of structure,the concept of flexibility matrix of node is introduced,and a new method to obtain the node flexibility matrix is proposed.A computer program is developed for the algorithm which is efficient to calculate the flexibility ellipsoids（ellipse） in cable-strut systems.