Study On Mechanical Characteristics And Fatigue Test Modol Of Tensile Anchor Plate Of Long-Span Cable-Stayed Bridge

The cable-girder anchorage is the key part of cable stayed bridge, which bear giant cable forces. The tensile anchor plates in cable-beam anchorage zones which have clear load path relatively simple structure, easy construction and maintenance, however also with serious local stress concentration and complexity of the stress distribut, are prone to fatigue failure under long-term dynamic load.Yuekou Hanjiang River Bridge which is under construction is an rare example which has tensile anchor plate in cable-beam anchorage zones in railway cable stayed bridge. The tensile anchor plate adopt design which weld the bearing plate on the tensile plate, increasing the cable force transmission path compare with the traditional design.The tensile plate has lateral deflection angle, penetration welding docking with steel box girder side web which extend above the deck. Takeing the bridge as the engineering background, this thesis launches research mechanical characteristics of tensile anchor plate in cable-beam anchorage zones, steel box girder top plate and side web, designing model of fatigue test. The main contents and conclusions of this thises are as follows:1. Analyze the values of the cable forces and angle of stay cables preliminarily, selecting the five tensile anchor plates in cable-beam anchorage zones under unfavorable force as alternatives which are M01, M10, M12, M13, M20. Establishing three segmental steel box girder tensile anchor plate models based on the tensile anchor plate in cable-beam anchorage zones above, analyzing stress state of the tensile anchor plate, steel box girder top plate and side web preliminarily, take M12 tensile anchor plate as the target to research mechanical characteristics and fatigue test model.2. Research the stress distribution state of the main plates in M12 tensile anchor plate, corresponding steel box girder top plate and side web under the most unfavorable cable force. Setting stress extraction point of each plates and extracting stress value, analyze the stress variation of each plates. Research the stress variations of the welds which connect plate and anchor tube, anchor tube and anchor tube stiffeners, tensile plate and side web, side web and top plate. Research the fatigue stress amplitude and extraction point stress of key plates of M12 tensile anchor plate.3. Directed against M12 tensile anchor plate in cable-beam anchorage zones, research the design about fatigue test model. Proposeing modifications through calculation and analysis, optimal design based on previous model, identify the model of programme IV as the fatigue test model.4. According to calculation and analysis, It is verified that the fatigue test model has better stress equivalence. the main plates of tensile anchor plate, top plate and side web of steel girder in the fatigue test model have similar stress distribution to corresponding plates in primary bridge three segmental steel box girder tensile anchor plate model. Except individual stress extraction point which is in tensile plate, top plate and side web, the value of stress extraction point in all the plates of the fatigue test model is similar to value which belongs to the corresponding plates of primary bridge three segmental steel box girder tensile anchor plate model. The stress values and variations of the welds of fatigue test model which connect tensile plate and anchor tube, anchor tube and anchor tube stiffeners are similar to the ones of primary bridge three segmental steel box girder tensile anchor plate model; the stress variations of the connection welds which is in tensile plate and side web, side and top plate are similar to the ones of primary bridge three segmental steel box girder tensile anchor plate model,with 25MPa stress sifferences basically.