跨座式单轨钢-混凝土组合梁群钉连接件力学性能研究

Study on Mechanical Properties of Group Nail Connectors of Straddle Monorail Steel-Concrete Composite Beams

跨座式单轨钢-混凝土组合梁是一种新型轨道梁体形式,自重较轻且安装便捷。群钉连接件的力学性能与布置形式是决定跨座式单轨组合梁力学性能的关键设计参数。为得到群钉连接件的力学性能,针对跨座式单轨组合梁的群钉连接件展开试验研究,共设计了4组推出试验,包括3组足尺试件和1组1:3缩尺试件,研究变量包括连接件个数、布置形式以及试件尺寸,得到了各试件的破坏类型、荷载与位移关系图和主要力学性能参数。根据试验结果,4组试件的破坏模式均为栓钉剪断的延性破坏,与极限变形分析的结果保持一致。同一试件槽口不同位置处栓钉应变不同,呈现“两边大,中间小”的分布模式,且随着荷载不断增加,这种分布模式依然保持。根据规范值对比,群钉效应导致足尺试件的抗剪承载力下降约23.4%~27.2%,且承载力下降幅度与栓钉布置的密集程度成正比。群钉效应导致缩尺试件的抗剪承载力下降约16.5%,明显小于足尺试件。尺寸效应对群钉承载力的影响并不明显。总体来看,通过试验综合研究群钉连接件的力学性能,并结合现有设计规范和理论方法给出群钉连接件承载力的计算方法,为相应工程应用提供设计建议。

Straddle monorail steel-concrete composite beam is a new form of railway structure with light weight and convenient installation.The mechanical properties and arrangement of group nail connections are key design parameters to determine the mechanical properties of the straddle monorail steel-concrete composite beam.In order to obtain the mechanical properties of the group nail,this paper carries out experimental research on the group nail of the straddle monorail composite beam,and designs four groups of push-out tests,including three groups of full-scale specimens and one group of 1∶3 scale specimens.The research variables include the number of group nails,the arrangement form and size of the specimens.The failure types,load-displacement relationship and main mechanical properties parameters of the specimens are obtained.According to the test results,the failure of the four group of specimens are ductile failure due to bolt shearing,which is consistent with the results of limit deformation analysis.The bolt strains at different locations of the groove of the same specimen are different,presenting a distribution pattern of“large on both sides and small in the middle”,which is maintained as the load increases.It can be seen that the group nailing effect reduces the shear bearing capacity of full-scale specimens by capacity.Due to the group nailing effect,the shear capacity of the scale specimen is reduced by about 16.5%,which is obviously smaller than that of the full-scale specimen.In general,the mechanical properties of group nail connections are comprehensively studied through tests,and the calculation method of bearing capacity of group nail connections is given by combining existing design specifications and theoretical methods,which provides design suggestions for corresponding engineering applications.