Research On Mechanics Of Concrete Creep And Its Application In Bridge Construction

Long span concrete continuous rigid frame bridge monitoring is to facilitate the construction of the bridge,to keep abreast of the force 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 provide the basis for scientific research. Among them, the linear control is the main content of construction control, linear control is mainly concentrated in the pre-camber settings, while the pre-camber setting is closely linked with the deformation calculated of the bridge structure. Long span pre-stressed concrete continuous rigid frame is the sensitive structure which to concrete creep, accurately predict the continuous rigid frame bridge cantilever construction phase of the creep effect has important practical significance.Creep effect of concrete bring certain difficulties in bridge construction control When monitoring bridge structures's deflection, concrete creep deflection can cause deflection increase or decrease, if not consider this part of the incremental deflection, deflection monitoring results will be distorted, then resulting in the bridge's stress state is misjudgment, cannot achieve the deflection monitoring's purpose. With the extension of the construction cycle and the cantilever length increases, the concrete creep deflection of the cantilever end is also increasing. Therefore, this paper carried out study on the continuous rigid frame bridge cantilever construction stage of concrete creep effects.This paper using Lanxi bridge in Xishui county of Hubei Province for engineering background, through the bridge construction site in Lanxi surveillance monitoring, collecting the elevation and related material property data in the construction phase. And using MIDAS software construction phase of the design model to calculate the pre-camber value. Compared with the measured deflection value, we can see in the MIDAS software calculation, material parameters are depend on a lot of material on the test data for regression to determined. In the actual construction process, the concrete is influenced by its construction of concrete mix and the impact of construction technology, material parameters has its own characteristics. The parameters obtained through the regression is different from the actual situation. Finally, combine the domestic and abroad progress in creep of concrete research, in this paper, conducted in-depth study and discussion in the mechanism of concrete creep, creep nature, the cantilever construction and the increasing load on the creep. Discussion relaxation modulus of concrete in different ages. Derivation of the cantilever deflection calculation formula in continuous rigid frame bridge construction phase. Pre-stressed concrete construction phase will be divided into the deformation of elastic deformation and creep deformation of two parts, according to creep theory with age adjusted by relaxation modulus and the superposition principle, proposed the section deflection formula in cantilever Lanxi bridge in Xishui County construction phase that contains T section of concrete creep effects caused by Comparative analysis of the results, the MIDAS measured data and the monitor data, derived a theoretical calculation formula in the establishment rigid frame bridge cantilever construction phase contains creep deformation of the deflection So that research results can guide continuous rigid frame bridge design of cantilever construction and construction control, effectively improve monitoring cantilever deflection accuracy during the construction of the continuous rigid frame bridge and ensure the smooth progress of the bridge closure and a good linear control to improve the continuous rigid frame bridge project quality.