支座平移法的有效性和局限性
The Effectiveness and Limitation of Support Translation Method

基于铰结三角形的几何不变性可衍生出系列判别规则，是现有教材中几何组成分析的主要教学内容。但实际问题复杂多变，几何法或将难以处理，其它各类分析方法便应运而生。作为结构力学的经典方法，支座平移法常用于几何组成分析中。根据典型算例，应用支座平移法和解析法分析体系的几何组成性质，并将分析结果与结构力学求解器的计算结果进行对比分析。结果表明：支座沿链杆作用方向平移，不改变约束的性质，支座平移是有效的，可应用支座平移法分析体系的几何组成性质，其它情况进行支座平移或将导致错误的结果。因此，支座平移法有适用性和局限性，在结构力学教学中需慎重使用。
Based on the geometric invariance of hinged triangle, a series of discriminant rules can be derived, which is the main teaching content of geometric composition analysis in existing textbooks. However, the practical problems are complex and changeable, and the geometric method may be difficult to deal with. Therefore, other kinds of analysis methods emerge as the times require. As the classical method of Structural Mechanics, the support translation method is often used in geometric composition analysis. According to the typical example, the support translation method and the analytical method are used to analyze the geometric composition of the system, and the analysis results are compared with the calculation results of the structural mechanics solver. The results show that the translation of the support along the axial direction of the hinged bar does not change the nature of the constraint, and the translation is effective. Here, the geometric composition of the system can be analyzed by the support translation method. In other cases, the translation of the support may lead to wrong results. Therefore, the support translation method has applicability and limitations, which should be used conditionally in the teaching of Structural Mechanics.