Research On The Transverse Mechanical Performance Of Steel Slab-concrete Composite Continuous Beam

The technology of steel-concrete composite beam bridge have developed rapidly in recent years at home and abroad.Steel slab-concrete composite continuous beam bridge is connected by a plurality of I-beams in the transverse direction to form a whole structure.It is necessary to consider the influence of the transverse mechanical performance about the safety and durability of the structure.The transverse mechanical performance of steel-concrete composite beam hasn't been stipulated systematically in the current domestic and foreign codes,and it should be studied further.Highway steel-concrete composite continuous beam was taken as the research objects in this paper.Through numerical simulation,experimental research and theoretical analysis,the research on composite continuous beam bridges' stiffness,transverse cooperative force,stress and deformation was carried out in detail.The effects of transverse connections,bridge decks and vehicle overload were analyzed to provide recommendations for optimizing the mechanical performance of composite beams.The main contents and results of the research are as follows:(1)Space finite element models of 3 × 40 m highway steel-concrete composite continuous beams were established by MIDAS Civil,and the transverse mechanical performance was analyzed.The numerical simulations of double-girder,three-girder and five-girder bridges were carried out respectively,and different sizes and spacing of the small crossbeams were used to study the torsional stiffness of composite beam bridges as well as the spatial cooperative performance of multi-girder bridges.The study found that increasing the sizes of the small crossbeams and decreasing the spacing of the small crossbeams could increase the torsional stiffness of the composite beam bridges to varying degrees.Among the three systems,the five-girder system was the most affected.The load transverse distribution coefficient of the five-girder steel-concrete composite beam varies along the longitudinal direction of the bridge is different from those in the traditional concrete bridges.It is recommended that the small crossbeams spacing of the 3 × 40 m highway steel-concrete composite beam with five-girder be set to 4 ? 8m.(2)Using numerical simulation,the influence of the height of the steel girders,the thickness of the bridge decks,and whether the ribs were installed on the bridge deck about the transverse stress and transverse distribution of vertical displacement of the bridge deck were compared and analyzed.The results show that the composite beambridges with double-girder,three-girder and five-girder should be provided with ribs and they can improve the displacement of bridge deck by increasing the plate thickness.It is not recommended to improve the transverse mechanical performance of the double-girder system through the girder height.(3)Proposed the use of ordinary concrete(NC)and ultra-high performance concrete(UHPC)laminated slabs to improve the stress of the bridge deck.Six components were designed and produced for static tests.Analysis of the strength,crack development,displacement changes,and strain distribution rules of the components show that the laminated slabs with UHPC on the tension side have higher bearing capacity,greater rigidity than others,and show ductility after entering the plastic section.NC-UHPC composite slabs can be used in the negative bending moment area of bridge deck to improve mechanical performance.(4)Based on the investigation and analysis,the overload models were determined.The result under numerical calculation about the transverse mechanical performance of the five-girder composite bridge was analyzed under different overload multiples(the ratio about the actual loading mass of the vehicle to the rated loading mass).It shows that the stress and deformation caused by the overload of the six-axle semi-trailer are the most serious among the models which involved in this article.And the transverse stress of bridge deck within 1m of the wheel changes greatly due to the vehicle load.The transverse stress at center axles of the vehicle is close to those at rear axles.The effect of eccentric loading of overloaded vehicles should be considered in steel beams design of the five-girder composite beam.