Research On Hinge Joint Damage And The Key Technology Of Transverse Prestressing Reinforcement For Prefabricated Hollow Slab Bridge

As one of the preferred bridge types for small and medium-sized span bridges,hollow slab bridges are widely used due to their unique advantages.However,due to various reasons such as design,construction and operation,the existing hollow slab bridges in China have frequently appeared hinge joint diseases in recent years,which seriously endanger the safety and durability of bridges.External transverse prestressing reinforcement technology has been widely used so far.In this thesis,combined with prestressed carbon fiber plate reinforcement technology,a new scheme of adding a pair of steel plates at the bottom of the hinge joint is proposed to improve the shear resistance of the hinge joint to a certain extent.The stress calculation of the hinge joint,tension control of transverse prestress,checking calculation of reinforcement design and comparison of reinforcement effect are studied in detail.(1)The influence line of transverse load distribution of hollow slab bridge is calculated by ABAQUS solid finite element software simulation,and compared with traditional hinged plate method and grillage method.The analysis of the stress distribution law of hinge joints shows that the stress at the transverse joints of each plate will be significantly different due to different load conditions.Under the most unfavorable partial load condition,the peak value of longitudinal normal stress at the bottom of the hinge joint exceeds the design value of the axial tensile strength of the concrete,and it is easy to produce transverse cracks.Under long-term overload and repeated load,the cracks begin at the bottom of the hinge joint and develop vertically until the penetrating hinge joint damage occurs.(2)According to the sensitivity analysis of hinge joint damage parameters,it is found that the critical point of "stress state of a single beam" is the degree of hinge joint damage "the length reaches 5/8 span and the depth reaches 90%".Considering the reinforcement scheme of the damaged hollow slab bridge,under the condition of uninterrupted traffic,the external transverse prestressed carbon fiber plate reinforcement technology is used to analyze the damage status of various hinge joints,and the design scheme of transverse prestress is compared and selected.The results show that the longitudinal reinforcement range should be L/4 ～ 3L/4 span,the spacing of each prestressed carbon fiber plate is 1 m,and the transverse anchorage position is about 0.23 m from the outermost side of the side plate.(3)On the basis of determining the reinforcement design of transverse prestressed carbon fiber plate,it is proposed for the first time to add friction steel plate at the bottom of the corresponding hinge joint.Under the action of transverse prestress,the friction force generated by the contact surface of the two steel plates can provide shear reinforcement for the hinge joint,and the force analysis and checking calculation are carried out according to the calculation example.(4)Finally,the above reinforcement design is compared in the finite element simulation of the entity,and the technical feasibility is demonstrated through the engineering example.The prestress loss after the reinforcement of the carbon fiber plate is considered.At the same time,the key technology of the construction of the transverse prestressed reinforced plate girder bridge is also introduced.The results show that the comprehensive reinforcement technology based on the external transverse prestress and the addition of shear friction plate is remarkable.