Structure Analysis Of Deck Pavement On New Orthotropic Steel Bridge Deck With Large-Size U-Ribs

Orthotropic steel bridge deck with large-size U-ribs is a new type of Orthotropic Steel Bridge Deck Based on the traditional orthotropic steel bridge deck,which increases the U-ribs opening and U-ribs spacing.Compared with the traditional U-ribs structure,the large-size U-ribs structure can greatly reduce the length of the weld and reduce the probability of the fatigue details of the steel structure cracking.Therefore,it has certain advantages in fatigue performance and economy,but it also has disadvantages such as insufficient lateral stiffness.Taking the project of Lianshiwan Bridge in Zhongshan West Ring as the engineering background,this paper mainly analyzes the mechanical response of the orthotropic steel deck pavement system with large-size U-ribs,and studies the mechanical response of different pavement forms and different structures of the orthotropic steel bridge deck.The research results are as follows:(1)Compared with the EA+EA flexible pavement structure,the SMA+UHPC composite pavement structure can significantly increase the local rigidity of the bridge deck system and improve the stress state of the pavement layer.The surface bending stress and strain of the composite pavement is reduced by more than 40%compared with the flexible pavement,the average shear stress and strain is reduced by more than 50%,and the maximum vertical displacement is reduced by nearly 30%.(2)The mechanical response of the non-uniform load to the pavement system is generally greater than uniform load.When the vehicle accelerates or brakes,the horizontal force load has a significant effect on the longitudinal shear stress of the pavement system.The transverse rigidity of the large-size U-ribs structure is weaker than traditional U-ribs structure,but the longitudinal stiffness is no big difference between the large-size U-ribs and the traditional U-ribs structure.In the longitudinal shear stress,the large-size U-ribs structure is significantly better than the traditional U-ribs structure,the stress and strain decrease between 10%～35%.the large-size U-ribs structure is also better than the traditional U-ribs structure in the maximum vertical displacement.(3)In the large-size U-ribs UHPC+SMA pavement system,the maximum surface temperature of steel bridge deck pavement can reach 61℃ in summer.Under the coupling of temperature and load,the transverse shear strain between SMA and UHPC is 10 times higher than normal temperature,the longitudinal shear strain is 17 times higher than normal temperature.In winter,although the temperature of the steel deck pavement system changes slightly,the flexural tensile stress of the pavement surface average increases 50%compared with normal temperature under the coupling of temperature and load.(4)According to the damage index of bridge deck pavement,the orthogonal experiment of five factors and four levels is carried out for the large-size U-ribs composite pavement system.Under the condition of 0.1 inspection level,the asphalt mixture modulus has a significant impact on the longitudinal tensile stress of pavement surface,UHPC thickness has a significant impact on the transverse tensile stress and vertical displacement of the pavement surface.The load horizontal stress coefficient has a significant impact on the longitudinal shear stress of composite pavement.The regression analysis of pavement damage index shows that the regression effect of each formula is significant at the test level of 0.05,which can reflect the change law between pavement damage index and the structural parameters of composite pavement.In summary,large-size U-ribs composite pavement structure is recommended for bridges with heavy traffic and heavy vehicles.The recommended design parameters range of pavement structure are as follows:asphalt mixture thickness 25-30mm,UHPC thickness 60-80mm,and steel plate thickness 12-14mm.According to the traffic volume,each structural layer can take the average value within the recommended range to be higher or lower.