Research On Transverse Bending Effect Of Deck In Twin-I Girder Composite Bridges Under Wheel Load

There isn’t calculation method for the transverse bending moment’s deck of twin-I girder composite beam bridge under wheel load in the current Chinese code.In practical design,designers often analyze bridge deck based on the calculation method in “Specifications for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts(JTG 3362-2018)”.However,the steel girder web of twin-I girder composite beam is thinner than that of concrete girder,so the supporting condition of bridge slab is closer to that of simply supported slab.It is worth studying whether the calculation method in “Specifications for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts(JTG 3362-2018)” is applicable to the deck in composite beam.What’s more,the remarkable transverse bending effect of twin-I girder composite beam cause tensile stress of studs.Tensile stress of studs has an impact on the structure.In order to solve this problem,this paper analyzes the applicability of the calculation method of “JTG 3362-2018” to the calculation of transverse bending moment of composite beam Bridges,and this paper also studies the distribution and influential factors of the tensile stress of studs.Based on the existing research results and finite element analysis,this paper studies the transverse bending effect of 2×35m twin-I girder composite continuous bridges under wheel load.The main research contents and conclusions are summarized as follows:(1)Based on ABAQUS finite element software,this paper studies the selection of structural elements,the simulation of prestressed bar and steel bar in the deck,the simulation method of studs,the contact relationship between deck and studs and the simulation of interface between steel beam and deck.he results of six ABAQUS finite element models with different element types,stud simulation methods and contact relations are studied.Compared with the results of experiments in previous literatures,a reasonable simulation method of twin-I girder composite beam is found.(2)Based on “JTG 3362-2018”,the calculation method for the effective working width of deck in composite beam is inclined to safety.The calculated value of transverse bending moment in mid-span of the deck of unit width based on finite element models is larger than that based on “JTG 3362-2018”.In order to ensure structural safety,it is suggested that the correction factor of transverse bending moment for the twin-I girder composite beam whose t/h is less than 1/4 should be 0.6.(3)The stiffener limits the deformation of the upper flange along with the deck,resulting in obvious the tensile stress of studs.The tensile stress of stud decays fast in the longitudinal direction of bridge.The setting of floor beam reduces the lateral deformation of twin-I girder composite girder bridges,so the tensile stress of studs in composite bridges with floor beam under wheel load becomes larger and the maximum tensile stress of studs can be increased by up to 317.97%.Among all the parameters,ratio of deck thickness to girder spacing has the greatest influences on tensile stress of studs.For twin-I girder composite beam with t-shaped stiffener on the inside,this paper suggests that the studs of the twin-I girder composite bridges near the stiffeners and floor beam should be properly encrypted.