Study On Mechanical Behavior Of Small Span Assembled Steel-concrete Composite Girder System With Hybrid Connections

The traditional steel-concrete composite girders are mostly cast-in-situ,which are not suitable for prefabricated and assembled construction and can not achieve rapid erection.And only using studs as shear connectors will cause discontinuity of force transfer between concrete deck and steel girder,which will reduce to the performance of composite girders.In this paper,a small-span assembled steel-concrete composite girder bridge is proposed,which can replace damaged concrete bridges rapidly.Through the design,fabrication and performance investigation of prefabricated elements,and the experimental analysis of the hybrid connectors used in composite girders,the mechanism of the hybrid connector and the mechanical properties of this type of steel-concrete composite girders are clarified.The main research contents and results are as follows:(1)The reasonable structure system of the steel-concrete composite girder bridge with assembled hybrid connections are designed and studied.The structure system formed by connecting standard precast concrete slab and H-shaped steel plate girder with studs and bonding connectors is established.The standard span and basic parameters of the composite girder bridge with hybrid connections are given.(2)Through 9 groups of push-out specimens,the mechanical properties of pure bonding connectors and hybrid connectors are discussed.The mechanism and resistance distribution of hybrid joints are analyzed.Finally,the stiffness distribution principle and the ultimate bearing capacity calculation method of hybrid connectors are obtained.(3)In order to study the mechanical performance and composite performance of steel-concrete composite girder bridges with hybrid connectors,four full-scale specimens of prefabricated elements of middle girders were designed and manufactured.Static tests of flexural performance were carried out,and load-deflection curve,load-interface slip curve and strain distribution curve along the height of the section were achieved.The flexural capacity,stiffness,interface slip performance and the conformity of the assumption of flat section of the specimens were analyzed.(4)Through ABAQUS 6.14 three-dimensional finite element simulation analysis,considering material nonlinearity and large structural deformation,the mechanical properties of composite girders during the whole loading process are simulated,and the results of finite element simulation are in good agreement with the experimental results.Based on the design code for steel-concrete composite bridges(GB 50917-2013)and the formulas in relevant foreign literatures,the calculation method of flexural capacity of the composite girders with hybrid connectors is given,and the rationality of the calculation method is verified by comparing the theoretical value with the experimental value..(5)On the basis of theoretical and experimental research on small-span assembled steel-concrete composite girder system,taking the pilot project of Shipo Bridge in Yuyao City,Zhejiang Province as an example,the key points of steel girder processing,prefabrication technology of concrete slab and construction technology of bridge erection are summarized.