| The stability of cold-formed thin-walled steel structures has been the focus of researcher who works in steel structures. With the use of new section shapes and high strength steel plates with thinner thickness, some new stability problems are brought simultaneously. At present, few theoretical and experimental studies about the stability behavior of the new section members under compression loading are provided, especially the study on eccentric compression member. In addition, the effective section method is not sufficient to calculating new section. Therefore, direct strength method has been proposed by foreign scholars. The direct strength method can only use to calculate channel and channel with edge stiffeners under compression loading or pure bending, and can not use to calculate channel and channel with edge stiffeners under eccentric compression loading now.In response to these problems, a total of 12 simply supported compression members under eccentric compression loading with three types of complicated sections including channels with complex edge stiffeners, channels with complex edge stiffeners and Σ type stiffeners in the web, channels with complex edge stiffeners and V type stiffeners in the web were tested. The ultimate load-carrying capacity, buckling mode and deformation behavior of these members were studied in this paper. The result showed that stiffeners in web could reduce the element width-to-thickness ratio effectively and increase the ultimate load-carrying capacity of eccentrically loaded members which eccentricity close to the web side obviously. This makes local buckling replaced by distortional buckling to control the failure modes of members. But it has a little effect on eccentrically loaded members which eccentricity close to the edge stiffeners side.Tests were simulated by finite element analysis (FEA). The analysis results agree well with experimental data. A total of 302 members with three different sections under eccentric compression loading were selected to be studied by nonlinear finite element analysis. The result showed that stiffeners in web could increase the ultimate load-carrying capacity and the utilization of steel of eccentrically loaded members which eccentricity close to the web side obviously. Σ type stiffeners in the web is better than V type stiffeners in the web. Influence of the effective centroid offset on carrying capacity under eccentric compression loading can not be ignored. The maximum value of the ultimate load-carrying capacity appeared in loading on the effective centroid. The thickness of the plate has a significant influence on channels with complex edge stiffeners and V type stiffeners in the web.Based on the existing calculation method of members under eccentric compression loading, combined with the direct strength method of members under compression loading and members under pure bending, obtain to the direct strength method of members under eccentric compression loading. Through 125 numbers of check computation of test results and 103 numbers of check computation of simulation results, the calculation method is suitable to calculate the load-carrying capacity of the single axis of symmetry channels with complex edge stiffeners and channels with edge stiffeners under eccentric compression. |
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