The Crack Cause Analysis Of Web And Roof Plate Of Continuous Rigid Frame Bridge And Consolidation Maintenance

Along with the rapid development of national infrastructure construction,prestressed concrete continuous box girder bridge has become one of the main bridge type with its large stiffness well smooth driving less expansion joints and simple maintenance on the highway construction.However the prevalence of the cracking problem has drawed more and more people’s attention as large numbers of the bridge was built.These bridges have no cracks under the checking of current code,but many of them appear serious cracks during its operation process,which is an threat for its safety and durability,thus affecting its further application on the highway construction.Therefore analysising crack cause and putting forward reinforcement and reconstruction measures is of great significance for continuous rigid frame box girder bridge.This paper first briefly list different types of cracks and the method of calculation analysis and the theory of finite element analysis of the continuous rigid frame box girder bridge,and then based on a prestressed concrete continuous rigid frame box girder bridge of heilongjiang province as engineering example,and do the field and load test for it.The test results shows that the bridge exists varying degree of cracking of its web anh roof plate,the bearing capacity of the superstructure and the crack resistance of the oblique section is insufficient.Using the Docter Bridge and Midas FEA finite element program to analysis the crack cause of the web and roof plate,the analysis shows that the loss of longitudinal and vertical prestress,overloading of live load,the lack consideration of the web plate inside and outside temperature is the main cause of the web cracking.Tensioning the roof of prestressed steel and overloading of live load is the main cause of the roof plate cracking. Last according to the result of appearance detection and the loading test result and the cause of cracking analysis to make the reinforcement principle and two reinforcement scheme,then making comparison of the scheme.As the scheme of external prestress unite paste steel is better then that of external prestress unite increase web thickness in improving the bearing capacity and the right and oblique section stress state and in controling construction quality.So choosing the scheme of external prestress unite paste steel as the final reinforcement scheme.