三种非线性梁柱单元的研究及单元开发

RESEARCH AND DEVELOPMENT OF THREE NONLINEAR BEAM-COLUMN ELEMENTS

罕遇地震作用下混凝土梁柱构件易进入塑性阶段而发生弹塑性损伤,正确地模拟结构进入非线性状态后的力学行为对评价结构的抗震安全性具有重要的意义。通过面向对象语言编制了基于宏观单元的结构弹塑性分析软件平台MESAP,增加了三种非线性梁柱单元:基于刚度法纤维单元、基于柔度法纤维单元及基于柔度法的塑性铰单元。通过算例分析三种非线性梁柱单元之间的差异。基于柔度法塑性铰单元的柔度矩阵积分方法可分为四种,通过算例讨论四种积分方法的差异。算例分析结果表明基于柔度法的塑性铰单元是一种精度高具计算成本低的宏观单元。Gauss-Radau积分法要求进行塑性计算的积分点只有两个,该积分法计算效率较高且精度良好,适用于整体结构的非线性分析之中,具有实际工程应用意义。

Since the elastoplastic damages occur in concrete structures and components in plastic stage under a severe earthquake,precise prediction of nonlinear behavior of structures in the earthquake is important to assess the seismic safety of the structures.A structural elastoplastic analysis program MEASP which bases on macro elements is compiled with object oriented language and three kinds of nonlinear beam-column elements are implemented in MESAP： stiffness-based fiber element,flexibility-based fiber element and flexibility-based plastic hinge element.Differences between the elements are compared by case study.Four kinds of integration methods for obtaining the flexibility matrix of the plastic hinge element are studied.The results show that a flexibility-based plastic hinge element is an accurate macro element with low computation cost.Only two integration points are required by the Gauss-Radau integration method handling a nonlinear analysis.It is accuracy and its computational efficiency is applicable in the entire structure nonlinear analysis and practical in engineering.