开孔板连接件塑性阶段受剪机理及荷载-滑移曲线特征研究

Shear resistance mechanism and load-slip curve features of perfobond rib connectors during plastic stage

为保证单孔PBL连接件在塑性阶段仍具备较高的残余受剪承载力和较好的延性,对22组未设置贯通钢筋和21组设置贯通钢筋的单孔PBL连接件的荷载-滑移曲线进行了统计分析,研究了板厚不小于9 mm的单孔PBL连接件进入塑性阶段后的受剪机理。在此基础上,根据荷载-滑移曲线的延性特征将其进行分类,并给出了判别条件。研究表明:单孔PBL连接件塑性阶段的残余受剪承载力由混凝土榫沿剪切破坏面的黏结力、侧向约束力提供的受剪承载力以及贯通钢筋的销栓作用组成。根据塑性阶段的侧向约束力情况,将单孔PBL连接件荷载-滑移曲线分为Ⅰ类、Ⅱ类与Ⅲ类曲线。可通过控制约束强度比,避免未设置贯通钢筋和设置贯通钢筋的单孔PBL连接件的荷载-滑移曲线出现延性较差的第Ⅲ类曲线,并可通过控制贯通钢筋比,避免设置贯通钢筋的单孔PBL连接件的荷载-滑移曲线出现经济性较差的第Ⅱ类曲线;可通过联合控制约束强度比和构造钢筋比,避免荷载-滑移曲线出现峰值点处荷载突变。

To ensure high levels of residual shear strength and ductility of perfobond rib( PBL) connectors during plastic stage,22 groups of perfobond rib connector specimens without penetrating rebar and 21 groups specimens with penetrating rebar were tested, and their load-slip curves were collected and analyzed. Then,shear resistance mechanism and load-slip curve features of perfobond rib connectors with single hole,where the thickness of steel plate was not smaller than 9 mm,during plastic stage were analyzed. Based on that,the load-slip curves were classified,and the classification criteria was given. It is found that the residual shear strength of perfobond rib connectors is consisted of the bond force at the shear cracking concrete interfaces,shear strength contributed by constraining force and the dowel action force provided by perforated rebar. According to constraining force during the plastic period,the load-slip curves of perfobond rib connectors can be classified into Type Ⅰ and Type Ⅱ with good ductility,or Type Ⅲwith poor ductility. By controlling the constraining force ratio,load-slip curves of Type Ⅲ with poor ductility could be avoided for perfobond rib connectors with and without perforated rebar. By controlling the perforated rebar ratio,loadslip curves of Type Ⅱ which are uneconomic could be avoided for perfobond rib connectors with perforated rebar. By controlling constraining force ratio and constructional reinforcement ratio together,sudden drop of shear strength at peak load could be avoided.