Study On Damage Simulation And External Prestress Reinforcement Test Of Single-box Multi-cell Continuous Beam Bridge

Prestressed concrete continuous box girder has been widely used by virtue of its many advantages and the improvement of construction technology,but there are many problems in the operation of prestressed concrete continuous box girder in many Bridges,such as beam body bending,beam body cracking,and so on,which seriously affect the normal use of the bridge.These diseases will develop with practice,so it is important to identify and treat them as soon as possible.Through effective treatment and reinforcement,the bearing capacity of the bridge can be effectively improved.Among the many methods of reinforcement,external prestressing is an active and effective method,which can improve the bearing capacity of the structure,improve the mid-span flexural state and increase the compressive stress reserve of the main beam.Based on the engineering background of a single box and multi-room continuous box girder in a city,the overall analysis of the structure is carried out according to the actual situation of the project,and the influence parameters of the structure downwarping and cracking are analyzed.Finally,the effectiveness of the reinforcement scheme is verified by static and dynamic load test.The main research contents are as follows:(1)the actual cracking state of the original bridge was described,and Midas Civil software was used to analyze the effects of prestress loss,structural overweight,stiffness reduction,concrete shrinkage and creep,and automobile load on the cracking and downwarping of the original bridge.(2)the damage state of the original bridge was simulated.The Midas Civil finite element analysis software was used to simulate several damage states of the supporting project,and the damage model was established and checked and analyzed.(3)according to the damage model,the external prestress reinforcement scheme is optimized for each structure in the damage state.The final reinforcement scheme is obtained by comparing and analyzing the reinforcement effect of several reinforcement schemes,and the model after reinforcement is finally established.(4)the static and dynamic load test before and after the supporting project is conducted,and the static load test compares and analyzes the deflection and stress changes before and after the reinforcement.The dynamic load test analyzes the change of fundamental frequency,damping ratio and impact coefficient before and after the reinforcement,and finally evaluates the reinforcement effect.