铝合金梁弯扭稳定系数的试验研究及数值分析

Numerical and experimental study on flexural-torsional buckling coefficient of aluminum beams

本文依托国家标准《铝合金结构设计规范》编制研究项目,采用数值分析与试验相结合的手段研究了铝合金梁弯扭稳定系数的计算问题。首先根据铝合金材料的Ramberg-Osgood本构关系,近似地将梁屈曲时截面边缘纤维的切线模量应用于全截面,由此得出无缺陷铝合金梁弯扭稳定系数的计算式;接着采用有限元数值模拟技术,应用壳板单元结合材料的随动强化模型,并同时考虑构件的初始缺陷,对强硬化和弱硬化合金分别拟合出Perry-Robertson形式的铝合金梁弹塑性弯扭屈曲稳定系数计算公式;最后,针对梁弯扭屈曲时侧向扭转的特点,合理设计了一套试验装置,并进行了铝合金拉伸力学性能的测定和10根跨中受集中力作用的简支工字梁弯扭屈曲承载力的测定,通过与试验结果的比较,验证了拟合公式的正确性。

Supported by the research work of the Code of Design of Muminum Mloy Structure, the numerical simulation along with an experimental study is carried out in this paper to establish the calculating method of flexural-torsional buckling coefficient of aluminum beams. Based on the Ramberg-Osgood stress-strain law of aluminum, the relationship between the flexural-torsional buckling coefficient of the perfect aluminum members under bending and the slenderness ratio is derrived with the assumption that the tangent modulus of all the beam section are the same as those of edge fibers when the beam buckles. By adopting shell element, which combines kinematic hardening meterial model, the Perry-Robertson formulas are classified by weak hardening and strong hardening materials of flexural-torsional buckling of aluminum beam members simulated according to a large number of numerical data produced by FEM with initial imperfection considered. Based on the characteristics of flexural-torsional buckling, a new test system is designed and a series of 10 lateral buckling tests on simply supported I-section beams as well as the subsidiary tension tests are described in this paper. Test results validated the fomulation proposed in this paper.