空间杆系结构实用几何非线性分析

从简单实用的角度论述了空间杆系结构的几何非线性分析方法。文中分析了非线性有限元方法的求解过程，特别强调决定几何非线性收敛结果的关键问题，即由节点位移增量计算单元的内力增量。通过引入转随转坐标系，论述了平面和空间梁单元小应变时单元内力增量的计算问题。针对杆系结构的大应变问题，从有限应变理论出发进行分析，提出了对该问题的有效处理方法，并且用实例进行了验证。计算结果表明，该实用几何非线性分析方法是可靠和有效的。

Geometrically Nonlinear Practical Analysis of Spatial Frames

From a simple and applied point of view, a geometrically nonlinear theory analyzing spatial frames was addressed. The key problem of calculating elemental force increments from nodal displacement increments, which dominates the last result of nonlinear iterative convergence, was especially emphasized based on the process of nonlinear FEM. By introducing corotational coordinates, the procedure calculating elemental force increments of planar and spatial beam elements in the small-strain deflection was discussed. For the large-strain problem, the paper proposed an effective approach from the finite-strain theory. The results show that the nonlinear methodology is reliable and effective.