冷弯薄壁型钢-细石混凝土组合梁抗弯性能研究

Study on Flexural Performance of Cold-formed Thin-walled Steel-Fine Aggregate Concrete Composite Beams

为研究冷弯薄壁型钢-细石混凝土组合梁的抗弯性能,对3个不同抗剪构造的组合梁进行了单调静载试验,考察了组合梁的破坏形式、承载能力等.组合梁的破坏特征为托梁腹板剪切破坏并出现扭转,托梁上翼缘屈服、部分抗剪螺钉拔起、混凝土出现贯通裂缝继而组合梁发生整体破坏.试验结果表明:设置抗剪件对组合梁极限承载力无显著影响但可提高组合梁抗弯刚度.建立ANSYS有限元模型进行数值模拟,并对验证后的有限元模型进行变参数分析,研究结果表明:减小螺钉间距、提高钢材强度、增加托梁腹板高度、增加混凝土厚度均会提高组合梁承载力.最后,基于考虑托梁腹板高度、螺钉间距等影响因素修正系数η,提出了组合梁抗弯极限承载力公式,并与试验结果、有限元结果对比,验证了公式的正确性.

In order to study the flexural performance of cold-formed thin-walled steel-fine aggregate concrete composite beams,static tests were carried out on three composite beams with different shear structures.The failure mode and bearing capacity of composite beams were investigated.The failure characteristics of composite beams include shear failure and torsion of joist web,plastic yield of upper flange of the joists,pull-out of part of the shear screws and cracks in concrete,which lead to overall failure of composite beams.The test results show that setting shear connectors has insignificant effect on the ultimate bearing capacity,but can increase the bending stiffness.An ANSYS finite element model is established for numerical simulation as well as parametric analysis based on the calibrated model.The results show that reducing the screw spacing,increasing the strength of steel,increasing the web height of joists or the thickness of concrete can improve the bearing capacity.Bending bearing capacity formulas with a modified coefficient which considers the influence factors of the web height of joists and screw spacing are proposed.The accuracy of the proposed formulas is verified by comparing the theoretical calculation results with the experimental results and finite element analysis results.