Study On The Evaluation Of Bearing Capacity And Optimization Of Reinforcement Of Continuous Beam Bridges With Pre-stress In Service

With the development of national economy,our country has transitioned from the primary stage of construction to the rapid development period of construction,the bridges built at the present stage are designed according to the new code and new standard,and there is a certain deviation in the bearing capacity of the bridge designed according to the old design code.After the reform and opening up,a large number of bridges,especially prestressed concrete continuous beam bridges,have been built because of the need of economic construction.Because of the backwardness of technology and lack of experience at that time,the construction of bridges was designed according to the load of vehicles at that time.Now,over the past 30 years,the traffic volume is increasing continuously,and the axle load of its vehicles is also With the increase of the service time of the bridge,the performance of the material is constantly degraded,so it is urgent to evaluate the bearing capacity of the old bridge.On the other hand,the maintenance and reinforcement of the bridge also needs the evaluation results of the bridge to support it.In view of this,this paper takes an in-service prestressed concrete continuous beam bridge as the background to study the following contents and draws the corresponding conclusions.The main results are as follows:(1)Whether the strain and deflection check coefficients of each measuring point under the equivalent static load of the most unfavorable control section meet the requirements,the actual strength and stiffness of the bridge,and whether the strength and stiffness of the bridge at the present stage of operation meet the requirements of the original bridge design load steam over-20,hanging-120.(2)The impact coefficient,the maximum dynamic deflection,the overall reaction performance and dynamic characteristics of the bridge were evaluated by experiments.(3)In view of the difference between the internal forces of the new and old design loads in each span,three kinds of reinforcement schemes are put forward,namely,increasing the thickness of the upper wing plate of the main beam,increasing the width of the lower part of the main beam and increasing it thickness of the lower part of the main beam.Finally,the three reinforcement schemes are compared from three aspects: increasing the weight of the bridge structure,strengthening effect and strengthening cost.(4)The mid-span deflection of the design load under the new and old codes is compared and analyzed.