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STUDY ON BEAM ELEMENTS FOR ELASTOPLASTIC BUCKLING BEHAVIOR OF CHORD MEMBERS IN TRUSS GIRDERS

桁架梁弦杆弹塑性屈曲行为的梁单元研究

基本信息

批准号：
13650621
负责人：
MOTOYUI Shojiro
金额：
$ 0.51万
依托单位：
TOKYO INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

We have developed a beam element that makes it possible to simulate the collapse behavior of a truss girder with local damages like the yielding and buckling phenomenon of chord members. In the element, the simplest model, which consists of two elastic straight bars and an elastoplastic rotary spring, is considered to represent the buckling behavior of chord members. The condition of the rotary spring after yielding is estimated with the generalized plastic hinge model in which the interaction of axial force and bending moment is taken account. But the generalized plastic hinge model is different from the actual. In this study, we present the new type of an elastoplastic beam element involving the change of plastic region size and the Baushinger effect. Applying the present element to our truss girder model enables us to simulate the actual behavior exactly. We obtained the following results :1.It was shown that the influence of hardening properties and the change of plastic region size via results of a truss girder by FEM. Furthermore, the basic concepts to formulate the influence of the hardening and the plastic region size were clarified.2.For the simplicity, the cross section shape of an elastoplastic beam element was assumed to be the 2-flange section type. According to the above-mentioned concepts, a new type of beam element was formulated. Each flange was assumed to have combined hardening properties with the constant hardening coefficient. The validity of the element was confirmed by comparison with results by FEM.3.We extend the above element to the case of a material with the Baushinger effect. Then we confirmed the validity of the extension by comparison with results by FEM.

我们开发了一种梁单元，可以模拟具有局部损伤的桁架梁的倒塌行为，如弦杆的屈服和屈曲现象。在单元中，考虑由两个弹性直杆和一个弹塑性旋转弹簧组成的最简单模型来表示弦杆的屈曲行为。采用考虑轴向力和弯矩相互作用的广义塑性铰模型，对旋转弹簧屈服后的状态进行了估计。但广义塑性铰模型与实际存在差异。在本研究中，我们提出了一种考虑塑性区尺寸变化和鲍兴格效应的新型弹塑性梁单元。将该单元应用于桁架梁模型，可以较准确地模拟实际受力情况。我们得到了以下结果：1。通过对一榀桁架梁的有限元分析，分析了硬化性能和塑性区尺寸变化的影响。此外，还阐明了计算硬化和塑性区尺寸影响的基本概念。为简单起见，假定弹塑性梁单元的截面形状为2翼缘截面型。根据上述概念，提出了一种新型梁单元。假定每个法兰具有恒定硬化系数的复合硬化性能。通过与有限元结果的比较，证实了该单元的有效性。我们将上述要素扩展到具有鲍兴格效应的材料的情况。通过与有限元计算结果的比较，验证了该扩展的有效性。