Study On Reason And Regularity Of Cracking And Increasing Of Deflection For Long Span PC Continuous Rigid Frame Bridge

Prestressed concrete continuous rigid frame bridge is a kind of better structure type. With the development of prestressing technique, small and medium span prestressed concrete continuous rigid frame bridge is widely used in China. The developments of large-tonnage group anchor and cantilever casting technique make it used widely. Up to now from 1980, a number of prestressed concrete continuous rigid frame bridges were built in china and the main span length of them are between 100m and 300m. But there are something wrong with the bridges soon after useing. Girder body is cracking and the deflection of it is increasing. This phenomenon is very common and severe in Most of bridges. In order to promote the development of the prestressed concrete continuous rigid frame bridge, this dissertation is to get reasons and regularity of cracking and increasing deflection.1. Firstly, the current situation of existed prestressed concrete continuous rigid frame bridge is investigated and studied. Some representative long span prestressed concrete rigid frame bridges are analyzed importantly2. The shrinkage and creep of concrete structure have prodigious effect on girder deformation and force of bridge. By analyzing some intermestic standards and theories of the shrinkage and creep of concrete and contrasting the calculate results against the test results for five bridges, author can get how them affect the force and deformation of prestressed concrete rigid frame bridge.3. How live load affects the creep deformation of this kind of bridge is researched into. Study shows that the creep deformation which is caused by live load can't be neglected. When the bridge is closured, stretching prestressing tendon reasonably and can decrease creep deformation.4.0# block of the prestressed concrete rigid frame bridge is large volume concrete. Hydration heat in concrete is very severe and it can make concrete cracking. This dissertation analyzes the temperature distribution during casting concrete. It will promote the development of reducing hydration heat method.5. The bridge over secondary channel of the Sutong Yangty River Bridge is studied. Author summarized the main factors which affect the quality and line shape of bridge, by real-time monitoring the construction. Results show that the main factors are concrete shrinkage, creep, strong wind, temperature, prestress construction error, the weight error of construction segment, hanging basket and constructuin temporary load.6. Based on the bridge over secondary channel of the Sutong Yangty River Bridge, the influence of all design parameters and construction process on the internal force and line shape of bridge is researched.7. Monographic study include:pier of a bridge is restricted by underground foundation, stability of cantilever in construction stage, prestress efficiency in longitudinal and vertical, transverse prestress efficiency, local stress influnce and so on. The results can help us understand prestressed concrete continuous rigid frame bridge.