Study On Structure And Fatigue Of A New Type Of Large Longitudinal Riborthotropic Steel-RPC Lightweight Composite Bridge Deck

Orthotropic steel bridge deck has many outstanding advantages such as light weight,high strength,wide applicability,and fast construction speed.At the same time,its complicated structure,more welds,stress concentration and other issues are more obvious,and due to the direct bearing of the local vehicle wheel The repeated effects of the load make the problem of fatigue more prominent.The development of a new type of bridge deck structure,through the optimization of the structural details of critical fatigue vulnerable parts,to improve the fatigue performance of vulnerable details is the development trend and direction of fatigue research of orthotropic steel deck.This paper takes the new large longitudinal rib orthotropic steel-RPC lightweight composite deck as the research object,taking the detail stress of the orthotropic steel deck as the control index,and the parameters such as deck thickness,beam thickness,diaphragm spacing,etc.optimization.Then,the factors affecting the effective flange width of the new large longitudinal rib orthotropic steel-RPC lightweight composite bridge deck were analyzed.Finally,based on the optimization model,the fatigue performance of the new composite bridge panel is studied.The main research work and conclusions are as follows:(1)Summarize the development history of orthotropic steel bridge decks,the factors of fatigue damage,and organize the distribution of fatigue vulnerable parts.Introduce the mechanical parameters of RPC and the concept of steel-RPC lightweight composite bridge deck.And research status.(2)Introduce the theoretical model of fatigue cumulative damage,elaborate the nonlinear,linear,bilinear fatigue cumulative damage theory,and summarize the advantages and disadvantages and similarities and differences of the three methods.In addition,the nominal stress method and the hot spot stress method are discussed,and their principles and similarities and differences are summarized.(3)Application of ANSYS modeling to pay attention to detail stress as a control index,sensitivity analysis of bridge panel thickness,beam thickness,diaphragm spacing and other structural parameters.The results show that reducing the spacing between beams and increasing the thickness of the diaphragm can effectively improve the fatigue performance of the bridge roof and the overall structure.The increase of the thickness of the top plate results in a decrease in the maximum principal stress of each target detail,especially in the connection structure between the top plate and the U rib.(4)Analyze and study the effective width factors of the flange of the lightweight composite bridge deck.It is found that the width-span ratio and the load type have a significant effect on the effective flange width of the flange,while the RPC thickness does not significantly improve the effective width of the flange.However,RPC is more advantageous than ordinary concrete in composite beams,effectively improving the effective width of the flange,but also reducing the thickness and self-weight of the composite beam.(5)On the basis of structural parameter sensitivity analysis,a finite element calculation model was established.The position and details of the fatigue of the structure are determined.Based on the stress history,the fatigue stress amplitude is calculated by the discharge method and the fatigue performance is evaluated by the nominal stress method.Studies have shown that this lightweight composite deck has better fatigue resistance.