大直径混凝土榫PBL连接件力学性能试验

Experiment on mechanical property of PBL connector for large diameter concrete dowel

PBL连接件作为主要的传力构件被广泛应用于钢-混组合桥梁结构中,为研究基于大直径混凝土榫的PBL连接件力学性能,设计了8组共24个试件,对其进行推出试验研究。根据推出试件的内部破坏状态分析了大直径混凝土榫PBL连接件的破坏形态及破坏机理;探讨了大直径混凝土榫PBL连接件抗滑移性能及承载能力的影响因素;从荷载-滑移曲线特征、抗剪刚度及延性性能三方面对比分析了不同直径混凝土榫PBL连接件的力学性能。研究结果表明:大直径混凝土榫PBL连接件的主要破坏形式有横向贯穿钢筋的剪断破坏、孔内混凝土的压碎破坏及开孔剪切钢板的受剪破坏3种;横向贯穿钢筋直径、开孔剪切钢板厚度及其破坏形态均为影响PBL连接件抗滑移性能的重要因素,剪切钢板的开孔直径对PBL连接件抗滑移性能的影响较小;横向贯穿钢筋直径、开孔剪切钢板厚度及其开孔直径是影响PBL连接件承载能力的重要因素;在大直径混凝土榫PBL连接件中,钢板开孔直径为75mm的PBL连接件的力学性能优于钢板开孔直径为60mm的,而钢板开孔直径为90mm的PBL连接件的力学性能优于钢板开孔直径为75mm的。研究结果为大直径混凝土榫PBL连接件的工程应用奠定了理论依据。

PBL connectors are widely used in steel-concrete composite bridges as a kind of main load-transferring component. In order to reveal the mechanical properties of PBL connectors for large diameter concrete dowel, push-out tests with 24 specimens in 8 groups were carried out. Failure modes and failure mechanisms of PBL connectors were analyzed according to the interior failure modes of these specimens, influence factors of bearing capacity and anti-slip property of PBL connectors were investigated, and mechanical properties of PBL connectors for different diameter concrete dowels were analyzed from three aspects of load-slip curve feature, shear stiffness, and ductility performance, respectively. The results show that there are three main failure modes of PBL connectors of large diameter concrete dowel, shear failure of transverse reinforcement, compression failure of concrete in the hole, and shear failure of perforated rib. Diameter of transverse reinforcement, thickness and failure mode of perforated rib are the important influence factors of anti-slip property of PBL connectors while perforated rib diameter has insignificant influence on anti-slip performance of PBL connectors. Diameter of transverse reinforcement, thickness and diameter of perforated rib are the important influence factors of ultimate bearing capacity of PBL connectors. Among the PBL connectors for large diameter concrete dowel, the mechanical properties of PBL connectors with perforated rib diameter of 75 mm are superior to those of 60 mm, and the mechanical properties of PBL connectors with perforated rib diameter of 90 mm are superior to those of 75 mm. The results provide theoretical basis for engineering application of large diameter concrete dowel PBL connectors. 4 tabs, 5 figs, 25 refs.