角钢连接件抗剪刚度试验及理论研究

Experimental and Theoretical Study on Shear Stiffness of Angle Shear Connectors

由于具有承载力高、疲劳性能好以及施工便捷的优点,角钢连接件在桥隧结构中得到越来越广泛的应用。角钢连接件主要应用于沉管隧道结构中,且相关研究主要集中在日本。现有研究多针对角钢连接件的承载力而忽视了抗剪刚度,而抗剪刚度会对界面滑移、混凝土开裂以及构件刚度等性能造成影响。为了研究角钢连接件的抗剪刚度,基于实际工程以及中国规范设计了6组推出试件,包含3种角钢尺寸以及2种混凝土规格。同时为了减少试验本身的离散性,每组均有3个试件。试验中所有试件均发生混凝土压溃破坏,混凝土强度提高时,试件的抗剪承载力和刚度均会相应调高,同一设计强度等级的3种尺寸角钢连接件受剪性能差别不大。曲率分布结果表明角钢腹板在底部承受较大弯矩和剪力,翼缘承受弯矩较小,表明翼缘在抗剪过程中的贡献较小。在结合已有的连接件理论模型以及试验结果的基础上,通过理论分析提出了针对角钢连接件的地基梁模型,并通过10组剪力-滑移曲线以及12组曲率数据来验证模型的可靠性,研究结果表明理论模型具有良好的精度。考虑到模型公式复杂,结合实际工程构造,对刚度公式进行了简化,并通过10组剪力-滑移曲线来验证简化公式的可靠性,结果表明简化公式同样具有良好的精度。

Angle shear connectors have garnered more applications in bridge and tunnel structures owing to their high shear strength,excellent fatigue performance,and convenient construction.Currently,angle shear connectors are mainly applied in immersed tunnels,and most studies related to angle shear connectors are mainly carried out in Japan.Existing research mainly focused on the shear strength of angle shear connectors and ignored their shear stiffness,whereas the shear stiffness will influence the interface slip,concrete crack,and the stiffness of structure members.To study the shear stiffness of angle shear connectors,6 groups of full-size push-out specimens were designed based on practical engineering and standard provisions in China,including 3 sizes of angle steel and 2 grades of concrete.To reduce discreteness,three duplicate specimens are present in each group.All specimens failed in the concrete crush mode of the experiment,and the shear strength and shear stiffness increase as the concrete strength increases.When using the same grade concrete,the shear performance of specimens with 3 sizes of angle shear connectors is similar.According to the curvature distribution data,the web of angle steel burdens larger moments and shear forces at the bottom while the flange burdens small moments,which indicates the small contribution of flange to resisting shear force.Based on the existing theoretical models and experimental data of angle shear connectors,the foundation beam model of angle steel was proposed via theoretical analysis.This model was verified based on 10 groups of shear-slip curves and 12 groups of curvature data and its results reveal the accuracy of the proposed model.Because the formula used in the proposed model was too complex,the formula of the shear stiffness was simplified according to the practical construction.The simplified formula was verified based on 10 groups of shear-slip curves;the results reveal the excellent accuracy of the simplified formula.