装配式组合梁PCSC剪力连接件剪切行为研究

Study on Shear Behavior of PCSC Shear Connectors for Prefabricated Composite Beam

针对装配式钢-混凝土组合桥提出了一种可快速施工且方便混凝土桥面板预制的剪力连接体系。为了验证PCSC连接体系的静力力学性能以及破坏模式,以新-老混凝土界面缺陷比例为试验参数,对10个试件开展了推出试验。建立了精细化有限元模型,分析了试验过程中试件内部栓钉和混凝土的力学行为以及栓钉直径、混凝土强度等参数对试件承载力的影响。结果表明:试件的最终破坏形态分为2类,第I类试件新-老混凝土界面完好,仅在钢-混凝土界面产生滑移,第II类试件在钢-混凝土界面和新-老混凝土界面均产生滑移,但在保证剪力连接钢筋的极限剪切强度高于栓钉后,连接体系的最终失效仍为钢-混凝土界面栓钉剪断;在新-老混凝土界面完好的情况下,PCSC连接件与常规连接件单钉承载力仅相差12.27%,极限滑移相差47.42%,如此小的差异说明在PC-C界面完好的情况下PCSC栓钉连接件与常规连接件的力学性能基本一致,如果钢-混凝土界面不做抹油脱黏处理,其黏结摩擦力将会引起约6.38%的荷载提升;当新-老混凝土界面存在缺陷时,其特征滑移值范围为6.12~45.47 mm,远大于EC4规定的6 mm延性要求,在界面连接钢筋强度高于栓钉的情况下,界面缺陷对该连接体系不会产生严重的不利影响;侧挡板承载力与栓钉直径、混凝土强度、界面摩擦系数呈正相关关系,栓钉强度对其影响不明显。

For the prefabricated steel-concrete composite bridge,a shear connection system which can be constructed quickly and prefabricated conveniently for concrete bridge deck is proposed.In order to verify the static mechanical properties and failure modes of the PCSC connection system,the pushed-out test on 10 specimens are conducted with the defect ratio of the new-old concrete interface as the test parameter.A refined finite element model is established,and the mechanical behaviors of the studs and concrete in the specimens during the test and the influence of the parameters such as stud diameter and concrete strength on the shear capacity of the specimens are analyzed.The result shows that(1)There are 2 types of final failure forms of specimens.The new-old concrete interface of the specimen type I is intact,and only slip occurs at the steel-concrete interface.The specimen type II has slip at both the steel-concrete interface and the new-old concrete interface.However,after ensuring that the ultimate shear strength of the shear connection reinforcement is higher than that of the stud,the final failure of the connection system is still the still stud shear at the steel-concrete interface.(2)When the new-old concrete interface is intact,the difference in single stud bearing capacity between PCSC connectors and conventional connectors is only 12.27%,and the difference in ultimate slip is 47.42%.Such a small difference indicates that the mechanical properties of PCSC connectors are basically the same as those of conventional connectors when the PC-C interface is intact.If the steel-concrete interface is not oiled and debonded,its adhesive friction will cause about 6.38%load increase.(3)When there are defects in the new-old concrete interface,the characteristic slip value is 6.12-45.47 mm,which is far greater than the ductility requirement of 6 mm stipulated by EC4.In the case that the strength of the interfacial connection reinforcement is higher than that of the stud,the interfacial defects will not have serious impact on the connection system.The bearing capacity of the side baffle is positively related to the stud diameter,concrete strength and interfacial friction coefficient,while the strength of the studs has no significant impact on it.