Research On Concrete Creep For Prestressed Bridge Camber Setting

The construction control for large span prestressed concrete continuous rigid-frame bridge is to facilitate the construction of the bridge, to keep abreast of the health status of the construction process, to ensure construction safety and to avoid an incident, and to ensure the construction quality of the bridge, but also to provide the basis for scientific research. Among them, the linear control is the main content of the construction control. The linear control mainly concentrated in the arch set of degrees, while the preset arch bridge with the structure and degree of deformation calculation are closely linked. As the inherent characteristics of the concrete material, creep of concrete material with its many uncertain factors is one of the key technical problemsof continuous rigid frame design and construction.For the prestressed concrete continuous rigid-frame bridges with the way of cantilever irrigating construction, due to the effect of the concrete construction of self-respect and the load in the cantilever construction stage, there is very big impact to wethere consider the creep of concrete construction effect on the deflection monitoring results. If not considered, concrete creep will appear serious monitoring errors, and influence the type of the bridge after arch degrees, also it is hard to ensure alignment of the bridge control effect. On the basis of the research background, this paper analyzes the creep of concrete of long span continuous rigid frame bridges in the process of the cantilever construction, through to the analysis of the affecting factorsof the construction deflection in the type of the bridges, based on the analysis of the causes of the actual engineering example construction and the degree trend of deflection bridge in the future, and give the suggestions to the feasible questions of the concrete creep effect in the arch bridge construction control.This paper firstly discusses the impact of concrete creep main, briefly introduces various classical theory to predicts the concrete creep effect, and on the basis of the existing countries or organizations proposed some commonly used creep effect paper prediction model, discusses the establishment of the model, the main factor of the consideration mechanism, and lay the theoretical basis for practical prediction model of the reasonable choice. Secondly through the establishment of a bridge finite element model, this paper simulates cantilever construction, get the model to calculate the arch degrees value, and compares the differences to get some section with the good condition that the overall trend is less than the differences.Finally this paper analyzes the arch setting method and all kinds of the factors of the arch setting influence, from the view of mechanics deduces the calculation formula considering the creep of concrete in the construction of cantilever segments. Taking a certain bridge as the example, this paper analyzes the influences of the creep effect on the arch setting, and the contrastive analysis is made with the fixed arch degrees value for the calculation, measured deflection value and model calculation value, and at last obtains the results that the arch deflection revised and the measured value degree is consistent much better.