新型可拆卸开孔钢管连接件抗剪性能

Shear Performance of a Novel Demountable Perforated Steel-tube Connector

为适用预制钢-混凝土组合桥梁快速装配化施工需求,提出一种新型可拆卸的开孔钢管连接件。通过设计不同钢管壁厚、开孔板条宽度与高度等参数的开孔方钢管连接构造试件,开展水平推出试验,研究其抗剪承载力、抗剪刚度、剪切破坏模式及相对滑移特征。考虑钢材理想弹塑性、混凝土塑性模型及钢-混凝土界面非线性接触,建立可拆卸连接件抗剪分析的高效精细有限元模型,并通过试验结果验证。采用验证的有限元模型,进行与方钢管具有相同用钢量、板厚、开孔形式的圆钢管连接件抗剪性能对比分析。研究结果表明:可拆卸钢管连接件不仅具有开孔板连接件相当的抗剪承载力,而且比焊钉连接件具有更好的延性;增加钢管壁厚能有效提高其抗剪刚度与强度,改变底部开孔形状对连接件的抗剪刚度影响较小,但对强度影响较大;圆管与方管连接件具有相当的剪切屈服强度,但方管连接件的极限抗剪强度更高,而圆管连接件的延性更好;塑性理论推导可拆卸连接件剪切屈服强度计算结果同试验、有限元结果吻合良好,证明该计算式准确、有效;建议荷载作用下,混凝土板不发生开裂和压溃,可拆卸连接件可屈服进入塑性状态,实现混凝土板、钢梁易更换、修复或重复利用。

To satisfy the accelerated assembly construction requirements of precast steel-concrete composite bridges, a novel demountable perforated steel-tube shear connector is proposed. Push-out tests using different parameters, including the wall thickness of the steel tube and height and width of the steel strips in a perforated plate, were carried out to investigate the shear strength, shear stiffness, failure modes, and relative slip characteristics of demountable perforated square steel-tube shear connectors. By considering the ideal elastic-plastic properties of steel, the plastic deformation model of the concrete, and the nonlinear contact behavior between the steel and concrete interface, an efficient finite-element(FE) model for a demountable shear-connector analysis was established and validated by the test results. A comparison of the shear performance between a square and a circular steel tube connector with the same thickness, perforated shape, and steel weight was conducted using the verified FE models. The experimental and FE analytical results demonstrate that the demountable perforated steel-tube shear connectors possessed not only the equivalent shear strength of perforated rib connectors but also better ductility than the welded stud connectors. The shear strength and stiffness can be improved by increasing the wall thickness of the steel tube. The perforated shape slightly affected the shear stiffness but largely affected the shear strength. The square and circular steel-tube connectors have almost the same shear-yield strength. However, the square steel-tube connector has higher ultimate shear strength, whereas the circular steel-tube connector exhibits better ductility. The calculation formula of the shear-yield strength of the novel demountable perforated steel-tube connectors was provided based on the plastic-analysis principle. Its accuracy and effectiveness were proven by the agreement of the calculation, test, and FE analytical results. Finally, under an applied load, concrete slabs are considered to do not crack or crush, and the demountable connectors can transform into a plastic state. Therefore, the concrete slabs and steel beams can be easily replaced, repaired, or reused.