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为了解冷弯薄壁型钢拼合箱形截面立柱的受力性能,对21根不同长细比的冷弯薄壁型钢单肢C形、U形及四肢拼合箱形截面立柱的轴压受力性能进行了试验研究,获得了试件的极限承载力和荷载-位移曲线,分析试件的屈曲模式和破坏特征,并采用《冷弯薄壁型钢结构技术规范》(GB 50018—2002)的有效宽厚比法、北美规范(AISI S100—2007)的有效宽度法、直接强度法及简单叠加法对拼合柱的极限承载力进行了计算和对比分析;采用ABAQUS软件建立了考虑材料、几何和接触非线性的有限元模型,对试验试件的轴压性能进行模拟分析,并将数值分析得到的破坏特征、荷载-轴向位移曲线与试验结果进行对比分析,验证了有限元方法的正确性;进而采用经验证的有限元模型对该类拼合柱轴压性能的影响因素(包括长细比、螺钉间距和腹板高厚比等)进行分析。研究结果表明:单肢中长柱试件破坏模式为局部屈曲和整体弯曲失稳,单肢短柱试件破坏模式为局部屈曲和畸变屈曲;中长拼合柱试件最终破坏模式为绕弱轴整体弯曲,短柱试件破坏模式为局部塑性折曲;拼合柱的极限承载力和刚度随长细比的增大逐渐降低,长细比大于30的箱形柱拼合效果显著,螺钉连接可以满足各肢协同工作的要求,长细比较小的箱形柱拼合效果差;采用简单叠加法计算承载力偏于不安全;减小箱形柱截面的腹板高厚比,其轴压极限承载力和刚度将显著提高。
In order to understand the bearing capacity of cold-formed thin-walled steel composite box-section columns, the axial compression properties of 21 single-limb C-shape, U-shape and four-limbs box-shape box columns with different slenderness ratios The ultimate bearing capacity and load-displacement curve of the test piece were obtained. The buckling mode and failure characteristics of the test piece were analyzed. The effective thickness of GB50018-2002 “cold-formed thin-wall steel structure” The effective width method, the direct strength method and the simple superposition method of the North American Code (AISI S100-2007) were used to calculate and compare the ultimate bearing capacity of the combined column. The ABAQUS software was used to establish the method of considering the material, geometry and contact nonlinearity The finite element model is used to simulate the axial compression performance of the test specimen. The failure characteristics and load-axial displacement curves obtained from the numerical analysis are compared with the experimental results to verify the correctness of the finite element method. The validated finite element model analyzes the factors that affect the axial compression performance of the split column, including the slenderness ratio, the screw spacing, and the web thickness-to-thickness ratio. The results show that the failure modes of single-limb long-column specimens are local buckling and global buckling, and the failure modes of single-limb short column specimens are local buckling and distorted buckling. The final failure mode of long- The failure mode of the whole bending and short column specimen is local plastic bending. The ultimate bearing capacity and stiffness of the composite column decrease gradually with the increase of the slenderness ratio, and the box-shaped column with the slenderness ratio greater than 30 has a good combination effect. The screw connection can satisfy The requirements of the joint work of various limbs, box slender column smaller than the combined effect is poor; simple superposition method to calculate the bearing capacity of insecurity; reducing the box column section web thickness ratio, the ultimate axial bearing capacity And rigidity will be significantly improved.