平面框架弹塑性分析的增量内力塑性系数法

提出一种分析框架结构弹塑性响应的新方法即增量内力塑性系数法。由该方法直接得到结构弹塑性增量割线刚度矩阵,并据此提出直接迭代算法求解结构增量平衡方程。研究结果表明:直接迭代算法与经典的牛顿-拉夫逊方法相比,它不用数值积分形成结构弹塑性切线刚度矩阵,也无需在每次迭代步中计算结构整体不平衡力,简化了计算过程;弹塑性增量割线刚度矩阵可以显式给出,减少了计算工作量,且计算结果与经典解析解以及其他数值解十分接近;采用增量内力塑性系数法分析一般平面框架只需采用至多2个单元离散框架构件就可以得到足够的计算精度。

Elasto-plastic analysis of planar frames by plastic-coefficient method based on incremental member forces

An accurate and efficient numerical procedure,referred to as the plastic-coefficient method based on the incremental member forces,was presented for the nonlinear inelastic analysis of planar frames.Based on the elasto-plastic stiffness matrix derived from this new method,the direct-iteration solution scheme was developed to solve the incremental equilibrium equations.The results show that compared to the Newton-Raphson method,the direct-iteration solution scheme is unnecessary to construct the tangent stiffness matrix or to calculate the out-of-balance force during each iterative step.The elasto-plastic stiffness matrix is explicitly given herein,hence,the entire analysis procedure is greatly simplified without any loss of accuracy,and the results are very close to the analytical results from limit analysis and the numerical results from other methods.The proposed method can be applied to analyze frames with sufficient accuracy using at most two elements per member.