Analysis And Experiment Study On Partial Stress Characteristics Of STC- Orthotropic Steel Bridge Deck Under Wheel Compression

Super Toughness Concrete(STC)-Orthotropic steel bridge deck is a new type of steelconcrete composite structure.Nowadays,with the increasing traffic volume and the frequent occurrence of overloading,orthotropic steel bridge decks are prone to fatigue cracking and pavement damage,which seriously threaten the normal use of the bridge structure.In this paper,relying on an arch bridge,taking the STC-Orthotropic steel bridge deck which is used in the bridge as the research object,carrying out the wheel pressure experiment,and the partial stress characteristics of STC-Orthotropic steel bridge deck composite structure under wheel load are studied by modeling and calculation with ANSYS.The main research contents and results are as follows:(1)By carrying out the field wheel pressure experiment,the stress characteristics of the key structural details in the action range of the tire are studied,finding the sensitive area of the structure.The results show that: At the intersection of the roof and the U rib,the longitudinal and transverse stress of the roof is the largest,which is the sensitive area of the structure;and the U rib plays the role of assisting roof,and its stress characteristic is similar to a small box girder,which the upper part of the U rib web is compressed,and the lower part and bottom of the U rib are tensioned.At the intersection of U rib and diaphragm,the tensile stress of U rib arc transition section will change abruptly,and this position also belongs to the sensitive area of the structure,which has a greater risk of damage,which needs to be paid enough attention to.(2)By changing the design parameters of the structure,the influence of structural design parameters on the mechanical performance of each member of STC-Orthotropic steel bridge deck under wheel load is discussed.The results show that: Properly increasing the thickness of roof,U rib and diaphragm has an obvious effect on reducing the partial stress of the structure,and the stress level of each member decreases,but it has little effect on the overall stiffness of the structure,the structural displacement doesn’t change much.When the diaphragm spacing is increased,the supporting effect of the diaphragm on the roof and U ribs gradually weakens,the stress level of the structure increases obviously,and the vertical displacement also increases;when the STC layer thickness is increased,the overall stiffness of the structure increases greatly,the stress level of each member decreases obviously,and the mechanical performance of the composite structure is significantly improved.(3)In this paper,based on the project,a small longitudinal beam is set up in the center of the bridge deck,and the influence of the beam on the structural stiffness can’t be ignored.The wheel pressure experiment is carried out to study the influence of the central small longitudinal beam on the overall mechanical performance of the structure.By changing the design parameters of the small longitudinal beam,the influence of the small longitudinal beam on the mechanical characteristics of the structure is discussed.The results show that :there is an obvious stress concentration at the intersection of the central small longitudinal beam and the steel bridge deck roof,especially in the case of eccentric load,and the setting of the central small longitudinal beam reduces the stress level of the structure as a whole,and greatly increases the stiffness of the structure,and the vertical displacement of the structure is reduced;Only changing the thickness of the web of the central small longitudinal beam has a limited effect on improving the mechanical performance of the structure.Increasing the height of the central small longitudinal beam can further improve the overall stiffness of the structure.When the design of the small longitudinal beam is equal to that of the main beam,the small longitudinal beam becomes one of the main load-bearing members of the structure from an auxiliary load-bearing member.It has the most significant effect on improving the mechanical performance of the structure.When the number of small longitudinal beams set in the transverse direction increases,although the overall stress and vertical displacement of the structure are obviously reduced,but the number of stress concentration parts on the roof also increases,which may have a certain impact on the later maintenance work.From the point of view of improving the mechanical performance of the structure,production cost,setting a small longitudinal beam in the center of the bridge deck is the most beneficial to improve the mechanical performance of the structure.