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讨论了一般强度和高强度多孔钢梁在组合屈曲模态下的非线性分析。建立一个考虑腹板和翼缘初始几何缺陷、残余应力和材料非线性等情况的多孔钢梁的三维有限元模型。用具有不同长度,不同截面,不同荷载条件和不同失效模态的多孔梁的试验结果验证了此有限元模型。该模型能计算多孔梁的失效荷载,跨中荷载-挠度关系和失效模态。用120根多孔梁的有限元计算数据进行了参数分析,研究截面几何尺寸,梁长和钢材料强度对多孔梁强度和屈曲性能的影响。参数研究结果显示:由于组合腹板的扭转和腹板后屈曲引起的多孔梁失效对承载力有很大的影响。对于长细比较小的多孔梁,应用高强度钢材料将能显著提高失效荷载值。将有限元计算得到的失效荷载与利用澳洲规范计算的多孔梁平面外屈曲计算结果进行了对比,发现规范的计算结果对于平面外屈曲的一般强度多孔梁是不保守的,而对于组合腹板扭转和腹板后屈曲的高强度多孔梁的失效则非常保守。
The nonlinear analysis of general strength and high strength porous steel beams under combined buckling modes is discussed. A three-dimensional finite element model of porous steel beam considering the initial geometric defects of webs and flanges, residual stress and material nonlinearity is established. The finite element model was verified by the experimental results of porous beams with different length, different cross sections, different loading conditions and different failure modes. The model can calculate the failure load, mid-span load-deflection relationship and failure modes of porous beams. The finite element analysis of 120 porous beams was used to analyze the parameters and study the influence of the cross-section geometry, beam length and the strength of the steel on the strength and buckling performance of the porous beam. The results of parametric studies show that the failure of the porous beam due to the twisting of the composite web and the post-buckling of the web has a great impact on the bearing capacity. For porous slender beams with small slenderness, the application of high-strength steel material will significantly improve the failure load value. Comparing the calculated failure load with the calculated results of the out-of-plane buckling calculated by the Australian code, it is found that the calculated results are not conservative for the general-strength porous beams with out-of-plane buckling. However, And the failure of high-strength porous beams with post-buckling webs is very conservative.