Research On The Mechanics Behaviors Of High-strength Prestressed Concrete Simply Supported Box Girder

Prefabricated prestrssed reinforced concrete box girder bridge is the preferred bridge type which is 20 to 40 meters in length,because of its reasonable structure stress,good integer property,high stability,controllable construction quality,fast-track construction,low cast,and so on.So far,there are thousands of prefabricated prestressed reinforced concrete box girder bridges in our country.This kind bridge is plagued by some problems caused by concrete crack,which affects durability and safety.High-strength concrete has some properties such as,high compressive strength,the relatively high tensile strength,high elastic modulus,low shrinkage and creep,uniform texture,good anti-permeability.This properties can raise the crack load of the box girder,increase the crack resistance,decrease the deformation,decrease initial cracks,prevent the premature cracks,decrease the prestress loss value caused by the shrinkage and creep and elastic shortening.This thesis carried out the destruction test of one C70 high-strength prestressed reinforced concrete box girder and one C50 prestressed concrete box girder,and made the nonlinear analysis by the finite element software ABAQUS.Then researched the impact of concrete strength on carrying capacity,crack resistance,deformation,characteristics of cracks,ductility properties.At last,we got the following conclusions:with the concrete strength increased from C50 to C70,the cracking load increased and the crack resistance improved obviously,the deformation of beam reduced,the distribution and development of fractures had few difference,but the carrying capacity did not increase,the ductility properties got worse.