Research On The Positive Bending Moment Mechanical Behavior Of Fully Assembled Composite Beams With Steel Joint Bridge Decks

With the continuous advancement of modernization,the rapid construction of bridges is gradually occupying the main position.This article proposes a new fully assembled steel-concrete composite structural beam using steel joint bridge decks and detachable high-strength bolt shear connectors.In order to investigate the positive bending moment mechanical behavior of fully assembled steel concrete composite beams,this paper conducted positive bending moment loading tests on three fully assembled composite beams with different steel joint bridge decks and one fully assembled composite beam with integral prefabrication,based on the National Natural Science Foundation’s "Design Theory and Intelligent Construction Method of Mountainous Prefabricated Hybrid Structure Bridges".The positive bending moment failure forms and stress characteristics of fully assembled composite beams with steel joint bridge decks were clarified,Establish a refined numerical model and conduct a full process behavior analysis of typical components.By comprehensively analyzing the mechanical properties of fully assembled composite beams with different steel joint bridge decks,it is determined that the bolted connection between the plates is the optimal steel joint form.The influence of high-strength bolt shear connectors and steel joint construction parameters on the bearing capacity of composite beams was discussed,and a formula for calculating the bending bearing capacity of fully assembled composite beams connected by bolts between plates was derived.The main research work is as follows:(1)Three fully assembled composite beams with steel joint bridge decks(steel plate connection,sleeve connection,and bolt connection between plates)and one prefabricated fully assembled composite beam were designed,and bending performance tests were conducted under positive bending moment two-point loading.By comparing and analyzing the failure forms,cracking loads,load displacement curves,slip distribution curves,and cross-sectional strain distribution of various composite beams,it is found that in fully assembled composite beams with steel joint bridge decks,the failure of steel plate connected prefabricated composite beams is more severe,and the material properties are fully utilized,resulting in the best ductility performance;The bending stiffness and cracking resistance of the composite beams connected by bolts between plates are the best;The sleeve connection has the best anti slip performance.(2)Combined with refined finite element modeling,verify the predictability of the numerical model using experimental results.By extracting the full process stress data of the joint connectors,bolt connectors at the joints,steel bars at the joints,concrete slabs,and steel beams of the fully assembled composite beam of the steel joint bridge deck,it is found that the deformation of the connectors,bolts at the joints,and steel bars of the fully assembled composite beam connected by bolts between plates is small,while the deformation resistance of the concrete and steel beams connected by sleeves is good.By comprehensively comparing the mechanical performance of fully assembled composite beams with steel joints,it is clear that fully assembled composite beams with bolted connections between plates have superior comprehensive mechanical properties.(3)The parameter analysis of five parameters,including the thickness of the lower flange of the steel beam,the height of the steel beam web,the concrete strength,the diameter of the plate beam bolt,and the pre tightening force of the plate beam bolt,was carried out using the fully assembled composite beam connected by bolts between plates as the research object.After comparison,the existing method for calculating the bending bearing capacity of the entire prefabricated composite beam,which is similar to the fully assembled composite beam connected by bolts between plates,is selected.Based on this,the influence of the pre tightening force of the bolts between plates and the bearing capacity of the high-strength bolt diameter of the plate beam on its bending bearing capacity is considered,and a modified calculation formula for the bending bearing capacity of the fully assembled composite beam connected by bolts between plates is proposed.And the applicability of the formula was verified.