Feasibility Study Of Fully Assembled B-G Shear Connection Composite Beam

With the continuous promotion of building industrialization,prefabricated composite beams have become a hotspot in the construction of prefabricated bridges.Relying on the science and technology project“Integrated/Half-assembly Steel-RC Combination Simple Supported Beam Bridge Construction Technology Research”(2018-MS1-019)hosted by the Ministry of transport,this article proposes the concept of“fully assembled B-G shear connection composite beams”,meanwhile uses the simulation analysis of large-scale finite element software ABAQUS.In this article,the structural details and mechanical properties of B-G shear connection composite beams are studied.Meanwhile,the feasibility of fully assembled B-G shear connection composite beams are explored.The main research work and conclusions are as follows:(1)This paper expounds the shear structure principle of the fully assembled B-G shear connection composite beam that shear steel bars and bolt reserved holes are set on the top of the prefabricated steel beam,at the same time,the reserved shear groove(Groove)and the embedded through screw(Blot)are set on the bottom of the segment precast concrete slab rib.The horizontal shear resistance of the composite beam is provided through the groove strip combination of the concrete slab and the steel beam interface.The screw bolt anchored on the top wing plate of the steel beam bears the pull-up force of the composite beam,the construction details of the composite beam are studied and perfected,and the construction scheme of the composite beam is discussed.The construction method of prefabricating the steel beam and the concrete slab in the factory,erecting the steel beam,assembling the concrete slab and anti pull bolt on site is adopted.(2)Using the large-scale finite element software ABAQUS,the solid finite element model of 30m fully assembled B-G shear connection composite beam is established.Based on the characteristics and key structure of the fully assembled B-G shear connection composite beam,the reasonable material constitution,element type,boundary condition and loading mode are selected,discussing the key structures such as the combination of beam and groove,the joint of precast slab and the anti pulling screw.In the simulation method,shear grooves are reserved in the concrete slab and the interaction simulation strip groove combination structure is established on the contact surface of the shear steel strip and the concrete slab.Through setting the bond layer to simulate the joint of the prefabricated slab,the nut and the steel beam adopt the hard contact,the screw and the steel beam do not set the interaction to simulate the pull-out non shear screw,thus forming the finite element of the fully assembled B-G shear connection composite beam.Based on the elastic-plastic theory,the yield moment M_y and ultimate moment M_u of composite beams are calculated,compared with the finite element analysis,the correctness of the modeling method is verified.(3)Combined with the finite element calculation results,the mechanical properties of the fully assembled B-G shear connection composite beam are analyzed,the load deflection curve of the composite beam from loading to failure is obtained,the stress change characteristics of the key components such as steel beam,concrete slab,shear steel bar,pull-out screw are analyzed.Stress change characteristics of key components such as force steel bars and anti-pulling screws;by setting the height of the steel bar,the length of the steel bar,the distance between the steel bars,the diameter of the screw,the height of the screw,and the distance between the screws as variables,and other parameters remain unchanged.It is the results that the influence of each variable on the mechanical properties of the fully assembled B-G shear connection composite beam is clarified and composite beams are divided into three stages from loading to failure.The failure characteristics of composite beams are typical bending failure and the influence of steel bar height and length on the overall stiffness of composite beams is limited,the influence of steel bar spacing on the stiffness and mechanical properties of composite beams is significant.With the increase of steel bar height,length and spacing,the failure model of composite beams,it has a transition trend from brittle failure to plastic failure;the increase of screw diameter will reduce the maximum lift displacement,on the contrary,the increase of screw spacing will increase the maximum lift displacement;the influence of screw height on the maximum lift displacement depends on the position of the acting point of the resultant force exerted by the screw due to the bending and rotation of the steel beam on the concrete slab.(4)Referring to the results of finite element analysis,combined with the existing research results,the simplified calculation method of shear bearing capacity of shear steel bars and the simplified calculation method of maximum lift displacement of steel beam and concrete slab are obtained by using the method of theoretical analysis.In conclusion,the simplified design formula of shear steel bars and pull-out screws in the fully assembled B-G shear connection composite beam is obtained.The comparison between the simplified calculation formula and the finite element calculation results shows that the two are in good agreement,which verifies the accuracy of the algorithm in this paper and lays a good foundation for the test and promotion of the fully assembled B-G shear connection composite beam.