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通过7根复杂截面薄壁铝合金轴压试件试验,研究了该类截面试件轴压作用下局部屈曲及局部与整体耦合屈曲的性能。试件长度分别为350 mm和190 mm;初弯曲方向分别沿截面对称轴和非对称轴方向;初弯曲取值分别为试件长度的1/500和1/70。分析了各试件的破坏模式、屈曲承载力及荷载-轴向位移曲线等。建立了非线性有限元分析模型,并利用试验结果,验证了有限元模型的正确性。采用验证的有限元模型,分析了615根不同板件厚度和构件长度模型的屈曲承载力。将分析结果与采用现行美国、欧洲和我国的铝合金结构设计规范,美国冷弯钢结构设计规范及直接强度法计算的屈曲承载力进行了对比。结果表明:各国规范均低估了复杂截面铝合金试件的屈曲承载力,其计算结果与有限元分析结果的比值均小于0.85;相比各国规范,直接强度法可更精确地计算复杂截面铝合金轴压试件屈曲承载力,其结果与有限元分析结果的比值约为0.90。
Through the experiment of seven thin-walled aluminum alloy axial compression test pieces with complex cross-section, the local buckling and local and total coupling buckling under axial compression are studied. The specimen lengths were 350 mm and 190 mm, respectively. The initial bending directions were along the symmetry axis and the asymmetry axis respectively. The initial bending values were 1/500 and 1/70 of the specimen length respectively. The failure mode, flexural capacity and load-axial displacement curve of each specimen were analyzed. The nonlinear finite element analysis model is established, and the test results verify the correctness of the finite element model. The finite element model was used to verify the buckling capacity of 615 different plate thickness and member length models. The results of the analysis are compared with those calculated by the current design code of aluminum alloy structure in the United States, Europe and China, the design code of cold-formed steel structure in USA and the direct strength method. The results show that all national codes underestimate the buckling capacity of complex cross-section aluminum alloy specimens, the calculated results are less than the ratio of finite element analysis results of 0.85; compared with national norms, direct strength method can more accurately calculate the complex cross-section aluminum alloy The buckling bearing capacity of the specimen under axial compression is about 0.90 with the result of finite element analysis.