Axial Load Capacity of Cold-Formed Steel G-Section Columns
为了解不同截面尺寸以及构件长度对G形钢柱破坏模式和极限承载力的影响，对18根名义厚度为2.0 mm的冷弯薄壁G形截面柱进行了轴压试验，分析了构件的破坏模式、荷载-位移曲线、荷载-应变曲线以及极限承载力。构件共有三种截面尺寸（名义腹板高度分别为150，200，300 mm），构件长细比的变化范围为15~70。试验前对构件的实际尺寸、材料属性和初始几何缺陷进行了测量。试验中观察到：名义腹板高度为150 mm的构件发生畸变屈曲破坏；对于名义腹板高度为200 mm和300 mm的构件，当构件长度小于或等于1 000 mm时，发生局部屈曲破坏，其余长度的构件发生局部与整体相关屈曲破坏，局部屈曲的半波长度与柱子腹板高度大致相等。
然后在有限元分析软件ABAQUS中建立有限元模型对构件进行模拟，并基于试验结果验证了模型的准确性。随后利用验证后的有限元模型分析截面翼缘宽厚比、腹板高厚比和复杂卷边尺寸对冷弯薄壁G形截面柱极限承载力的影响。结果表明，G形截面柱极限承载力随着翼缘宽厚比以及复杂卷边尺寸的增加而增加，随着腹板高厚比的增加而降低。Abstract: Cold-formed thin-walled steel columns can be made into many sections, of which the U-section (also called channel section) and C-section are the most commonly used and studied. However, although the cold-formed thin-walled steel column has the advantages of light weight and short construction period, it is also prone to buckle, which is not conducive to structures. Previous studies have shown that the cold-formed thin-walled steel channel columns with complex edge stiffeners (also called G-section columns) have higher load-bearing capacities and critical distortional buckling stress. In this paper, the axial behavior of pin-ended G-section columns was studied by means of experiments and finite element analysis.
In order to study the influence of cross-sectional dimensions and column lengths on the failure modes and load-bearing capacities of G-section columns, a total of 18 cold-formed thin-walled steel G-section columns with nominal thickness of 2.0 mm were tested, and their failure modes, load-displacement curves, load-strain curves and ultimate capacities were analyzed. There were three kinds of cross-sectional dimensions (nominal web depth was 150 mm, 200 mm and 300 mm, respectively), and the slenderness ratios of specimens varied from 15 to 70. Before the tests, the actual dimensions of cross-section, material properties and initial geometric imperfections of the specimens were measured. In the test, it was observed that the specimens with nominal web depth of 150 mm failed in distortional buckling; for the specimens with nominal web depths of 200 mm and 300 mm, when the length of the specimen was less than or equal to 1000 mm, local buckling failure occurred, and the rest specimens failed in local-global interactive buckling, and the half-wave length of local buckling was approximately equal to the web depth.
Then, the finite element models were established in ABAQUS to simulate the specimens, and the models were validated based on the test results. The calibrated finite element model was subsequently adopted to investigate the influence of the flange width-to-thickness ratio, the web depth-to-thickness ratio and the dimension of complex edge stiffener on the ultimate capacities of the cold-formed thin-walled steel G-section columns. The results showed that the ultimate capacity of the G-section column increased with the increase of flange width-to-thickness ratio and the dimension of complex edge stiffener, and decreased with the increase of web depth-to-thickness ratio.
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