Stress Monitoring And Evaluation On Fatigue-prone Details Of Continuous Girder Bridge With Steel-UHPC Composite Deck System

Ultra high performance concrete(UHPC)with high intensity,high toughness and good durability.Steel-UHPC composite overlay is a new type of bridge deck overlay.Fochen bridge is located in foshan,Guangdong,Fochen west extension bridge are three span continuous beam bridge,the bridge deck is steel-UHPC combined orthotropic steel bridge deck.Paper take Fochen west extension Bridge as the engineering background,Through field tests and finite element calculation,monitoring and analysis of the orthotropic steel bridge deck stress response characteristics of structural details,and make fatigue life evaluation for the details sensitive to fatigue.In this paper,the main content is as follows:Obtained stress data of seven days of the Fochen west extension bridge structure details by field tests.The 24-hour stress histogram and typical stress peak maps of the structural details were obtained.Analysis of each detail stress response characteristics of the structure,adopted the rain flow count method and based on the Miner cumulative damage rule calculated equivalent stress amplitude of each structural details,adopted AASHTO LRFD specification standard S-N curve evaluate the fatigue life of some details.Study shows that the stress of the cutout is bigger than other details,but the stress curves of cutout can't identify each axle in axle group.All the structural details of the fatigue life are greater than the 100 years of design life of the bridge.Analyzed surface and inside stress response characteristics in cutout based on field test stress data of orthotropic steel bridge deck cutout of Fochen west bridge expansion.Study shows that the same transverse diaphragm,each cutout outside surface stress changes trend of basic consistent,but face internal stress difference is very big.Adjoining transverse diaphragm's surface stresses in the similar change trend,outside surface stress difference is very big.Finally,built orthotropic steel bridge deck with steel-UHPC overlay finite element model.Loaded with standard fatigue truck in highway steel bridge design specification,obtained the stress response of the deck butt weld,the longitudinal rib butt weld and cutout,three details in total,analyzed the characteristic of the stress response and estimated the fatigue life based on middle valve of traffic volume in AASHTO LRFD specification.Also calculated stress value of the three details in the model without overlay,and coMPared with the model with UHPC overlay,analyzed of the property of steel-UHPC composite bridge deck overlay to reduce the stress value in orthotropic steel bridge deck.