The Local Diffusion Effect Of Wheel Load On Orthotropic Steel-concrete Composite Deck

Orthotropic steel-concrete composite bridge decks would be an effective solution to the two major design problems of concrete cracking and steel fatigue cracking due to the wheel-load diffusion and local stiffness increase from the composite action.The design of orthotropic steel-concrete composite decks consider the wheel-load diffusion effect of the concrete overlay based on the stress diffusion angle of 45° used in the pavement design.The transverse stiffness distribution of orthotropic steel bridge deck is uneven,and the diffusion angle may be inappropriate for the orthotropic steel-concrete deck.Therefore,this thesis focuses on the wheel-load diffusion on orthotropic steel-concrete composite deck based on the practical parameters of the steel bridge deck and its experimental research in recent years.The main conclusion are as follows:Aiming at the influence of uneven transverse stiffness,a spatial finite element model was establish to analyze the pressure stress distribution of the top plate of steel deck under different parameters,including wheel-loading pattern,U-rib forms and spacing,and the diaphragm spacing.The results show that the current design parameters of orthotropic steel bridge deck have slight effects on the wheel load diffusion.In order to study the effect of the concrete overlay on wheel load diffusion,longitudinal and transverse diffusion angles are obtained under different elastic modulus and thickness of the concrete overlay.The results show that the diffusion angle increases with the elastic modulus of concrete.The transverse diffusion angle ranges from 26 ° to 71.6 °,the longitudinal diffusion angle ranges from 25 ° to 63 °.The diffusion angle also increases with the thickness of concrete overlay.The transverse diffusion angle ranges from 71.6 ° to80 °,the longitudinal diffusion angle ranges from 45 ° to 62 °.The shear stiffness of steel-concrete interface has effects on steel-concrete composite action as well as the wheel-loading diffusion effect.The effects of flexible and the rigid shear connectors on the diffusion effect were studied.The results show that the longitudinal diffusion angle of PBL is slightly larger than the headed stud shear connector,and,the headed stud shear connector has slight effect on the diffusion effects.To sum up,the thickness of the concrete overlay practically is the main factors that affecting the wheel load diffusion effect.The research results would referred to the design of orthotropic steel-concrete composite bridge decks.