力法去弹性支座多余约束的一种处理方式

AN APPROACH OF REMOVING REDUNDANT ELASTIC SUPPORT FOR SOLVING STATICALLY INDETERMINATE STRUCTURE BY THE FORCE METHOD

  • 摘要: 针对带弹性支座多余约束结构力法计算问题,在分析弹性支座计算特点基础上,提出一种解除弹性支座固定支点约束、保留完整弹簧作为基本结构一部分的去弹性支座多余约束处理思路,一方面便于利用原结构弹簧固定支点处已知的零位移条件建立形式统一、意义明确的力法典型方程,方程系数和自由项均为基本结构中弹簧解除约束点处的绝对位移;另一方面弹簧变形对计算的影响限于主系数,将弹簧看作附着于基本结构的轴力单元,主系数可由杆件弯曲变形产生的主位移与弹性支座柔度系数叠加得到。解除支座固定支点的去多余约束方式对拉压弹性支座、转动弹性支座及刚性支座均适用,可规范力法求解过程和提高计算效率。

     

    Abstract: The calculation characteristic of elastic support is analyzed in order to calculate the response of structure with redundant elastic supports by the force method. An approach of removing the restraining action of redundant elastic support is proposed, which aims at releasing the support conditions of springs at base and retaining springs as a part of the primary structure. In this way, the zero displacement condition at the base of springs in the actual structure can be utilized to establish the geometric compatibility equations in a more direct manner. The linear or angular flexibility coefficients in compatibility equations are equal to the absolute displacements of the released structure. The meaning of the equation is definite and concise. Spring deflection influences the calculation of the principal coefficients only. Treating the springs as axially-loaded elements, the principal flexibility coefficients can be evaluated by superimposing the flexibility coefficient of elastic support and the elastically restrained nodal displacement or slope produced by a unit force acting on the primary structure. The proposed method of removing redundant restraint is applicable for redundant axial elastic support, rotational elastic support and rigid support, which can standardize the process of calculation and improve the calculation efficiency for the Force Method.

     

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