The Concrete Evaluation And The Structure Technology Reform Of The Railway Bridge In Arid Region

Through the investigation and analysis of the bridge diseases on several railway lines,the factors of diseases of railway bridges are numerous.That is to say,many diseases of the railway bridge have emerged during the service.In order to guarantee railway bridge has good usability and security,the bridge should be made condition evaluation on a regular basis.The response is made according to the results of evaluation.For there has been a servious disease,the bridge should be taking the appropriate transformation method based on the specific situation.Depend on the BaoLan railway K567+371 reinforced concrete bridget,first of all,the bridge was made condition assessment,and then found that the mian diseases reflect on the concrete beam,in connection with the bearing capacity evaluation of concrete beams,this paper introduced the elastic wave method concrete strength curve in arid,and tested the beam concrete strength.the testing results found that: beam body could not meet the resquirements of train running,then the replacement of the girder was puts forward in this project.The main research contents and results are as following:?1?In order to guarantee the precision of the measured curves,through laboratory tests,the influence of the different height to width radio,aggregate and tested surface were analyzed in this paper,and give the corresponding correction coefficient according to the influence degree.The strength-measuring curve is built on the basis of the pebble concrete and pouring lateral side,so the influence factors are used as the basis for correction.Conclusions are as follows:?1?differrent size of height to width radio of concrete specimens should slightly be revised in testing wave velocity because of the influence of the lateral boundary condition.?2?The aggregate has influence on the strength-measuring curve,and the correction coefficient is ?=1.05.?3?During the test,the test surface has a certain influence on the wave velocity test.When the test surface is the concrete structure pouring surface,the correction coefficient is ?=1.03;When the test surface is the bottom surface of the concrete structure pouring surface,the correction coefficient is ?=0.97.?2?Commonly used concrete mixture ratio in arid region was selected and used and concrete standard test block was precasted in this paper.first of all,testing elastic wave velocity and compressive strength.Then analysising the data of wave velocity and compressive strength with using the least square method and building elastic wave method concrete strength-measuring curve is f=0.7028v^3.2529.And the applicability was verified by test block for the same conditions bridge near Lanzhou.?3?Through dynamic character analysis for special-shaped beam and original PI beam.It is concluded that the vertical stiffness of special-shaped beam is not reduced and slightly larger than the original pi beam.The lateral stiffness of the beam is much larger than the original pi beam.It is proved that two beams coupled as a whole is rational.Then through the control section of the special-shaped beam stress check.It is concluded that the stress of each section of the special-shaped beam can meet the requirement of bearing capacity.Finally,in the case of the most unfavorable load combination,the maximum deflection of the shaped-beam could meet the requirements of the specification.