The Research Of Newly Steel-Concrete Bridge Deck Structure And Materials

Steel-concrete bridge deck is a bridge-beam structure installed on the bridge girder where bridge deck and beam can endure the stress together.At present,concrete bridge deck has heavy weight,poor performance on durability and poor entirety,thus requiring frequent maintenance and high cost of infrastructure.Bridges consisting of this kind of bridge deck has too much bridge disease and can crack easily under the repeated and large volumes of traffic,leading to the girder corrosion and loss of the service life.Based on GuanSheng-Qujiang CFST arch bridge with spanning length of 320 m in Guangan,this paper developed the steel-concrete bridge deck with an excellent combination of light weight,poor entirety,low cost,simple construction techniques and no need for mold.And this steel-concrete bridge deck also can be prefabricated in the factory and easily controlled in quality,which has made it wide applications in the small and medium span highway bridges and large CFST arch and cable-stayed bridges.The results of this paper are presented as follows.This paper developed cement-based composite of low shrinkage and light weigh t and high toughness.And in this paper we used high strength and pre-wetting ceramsite and pottery sand as an alternative to quartz sand in ECC where ceramsite and pottery sand can maintain the cement-based composite and reduce its shrinkage and bulk density.Then we utilized multi anchor steel fibers and PVA fibers with different sizes and reduced the adding content of PVA and AC-EA type II expansion agents to improve the work ability and toughening ability and to further reduce the shrinkage of cement based materials.And ultra dispersed and the plastic viscosity water reducer was used in the experiment to improve the workability further and to make it available in pumping construction.In this case,the specimen of cement-based composites has been cast with the volume weight,compressive strength,flexural strength,coefficient of drying shrinkage at 28 days,modulus of elasticity,flexural toughness index I20 of 1840kg/m3,62 MPa,9.2MPa,126×10-6,8.76 GPa,24.01 respectively.And the bending fatigue life limit exceeded 3.2×106 cycles under flexural fatigue load with stress level of 0.65.Based on the developed cement-based composite of low shrinkage,light weight and high toughness,this paper proposed a newly-designed steel-concrete deck structure of“top steel plate + shear plate+ piercing reinforcing bar + steel mesh”installed on the bridge girder.Through finite element mechanical simulation analysis and 1:2 scale model of the static and dynamic test,we studied the mechanical behavior of steel-concrete bridge deck and the relationship between shear properties,ultimate bearing capacity and flexural tensile fatigue ability,thus determining the strength grade of cement based materials and component structure design parameters of top steel plate,hole plate and steel mesh.On the bridge girder,we set the top steel plate with thickness of 6mm to10 mm on which we set a shear plate with a circular hole according to bridge girder supporting conditions.The height and spacing of the shear plate is 50 mm to 80 mm and 300 mm to 500 mm respectively.The hole diameter is 40 mm to 60 mm and central hole spacing is 100 mm to 150 mm.Then we pierced the 12 mm reinforced bar through the hole and set on shear plate the longitudinal reinforced bars on which we poured high-toughness cement-based material with thickness of 120 mm to 200 mm.The results of fatigue experiment showed that the fatigue life limit of this newly-designed steel-concrete bridge deck is two times as long as its designed service life.During the service life,stiffness degradation and stress increment caused by fatigue is small,leading to the excellent flexural fatigue performance in resisting the transportation load.The newly-designed steel-concrete bridge deck with light weight,strong stiffness,low cost desired bearing capacity and anti-fatigue ability can be easily and widely utilized in construction,leading to its extensive application prospects in future.