Analysis On Structure Performance Of Bridge Cantilever Constructing Under Concrete Strength Irregularity

With the rapid development of large span prestressed concrete bridges,the cantilever casting method has the advantages of good structural integrity,easy to control the deformation, not restricted by terrain restrictions or navigation under the bridge etc,so it is used widely.In the process of cantilever casting construction,concrete is affected by the factors such as mixture ratio and the curing conditions,not only the strength and elastic modulus of concrete is different from the original design value, and the strength and elastic modulus of concrete of each segment will be,so as to make the bridge structure deviate from the value of the original design.Therefore, it has important theoretical significance and engineering practical value of researching each segment of the strength and elastic modulus of concrete differences on bridge structure.This paper took the prestressed concrete T-shaped rigid frame bridge in a new railway line as the engineering background,with the aid of the finite element calculation software,through the reasonable parameter assumptions,it was researched that the effect of different concrete strength and elastic modulus on the bridge structure.By modifying the elastic modulus of concrete,the effect on the displacement of completed bridge phase was researched, and the scope of reasonable elastic modulus was given through the qualitative analysis;By modifying concrete strength of each segment,it was studied the effect of different concrete elastic modulus of each segment on the stress of the root of cantilever,mid-span and the maximum cantilever in the construction phase.The results of the study show that the modified concrete elastic modulus affected the displacement of bridge in the stage of completed bridge.When the elastic modulus of concrete was 1.0 ~ 1.1 times of design value,the discreteness of deflection was small and got a better control.When the elastic modulus of concrete changed, it had a greater influence on the deflection of the girder from 1/4 span to max-cantilever end.When the development function of concrete strength and elastic modulus modified,it had no effect on the stress before the structure system change,But after the structure system changed,the concrete elastic modulus affected the deflection,,thus changed the stress of the root of the cantilever, mid-span and maximum cantilever end,and when the concrete strength was greater one level than the design value one level, stress deviation was smaller values of the design.