Research On Concrete Creep In Pre-camber Setup Of Bridge

It is important to accurately estimate and predicate the deformation and long-term deflection of long-span bridges with high piers which arise from the effect of shrinkage and creep for engineering design,quality control and construction process. To set pre-camber properly is the guarantee that the surface structure of bridge could reach perfect linearity expected under the course of construction and force by vehicles, after upwards and downwards again and again.The setting of pre-camber of bridge is not just related to computing model, but more is to many factors which including first constant load, namely is the weight of beam and pre-stress of bridge, temporary load in construction, base subside, humidity variety, construction error and so on. There are many illegible and random factors in those main factors. It is the most difficult thatThere are many theories about concrete creep, the calculation modeling is different which based on different influencing factors. In conclusion, there are two calculation modeling style of creep coefficient: one is expressed by multiplication of different subentry coefficient, for example as ACI209(1982). Another is expressed by addition of different subentry coefficient ,for example as CEB-FIP(1978).The paper studies the creep theory and creep mathematic modeling in mashuihe brige, The achievements and conclusions are listed as follows:(1) Based on the ACI model and CEB-FIP model the concrete creep was calculated and forecasted. The results have more than 20% error. But if the material parameters is correct, the results still can be used.(2) The existing shrinkage and creep forecast model, material parameters are passed to the large number of data and determine the return fitting. Through regression method parameters are satisfied with the overall test data representative of the "common". But concrete shrinkage and creep properties of the materials, construction technology very influential "personality" significantly. Therefore, the large-span prestressed concrete bridge, in view of the actual concrete materials, through on-site test the accuracy of the material parameters, we can get more accurately the material properties, so shrinkage and creep of concrete long-term forecast accuracy.(3) The impact of concrete shrinkage and creep of very complex factors, the current forecast model is not fully consider the impact of these factors, as accurately as possible the reaction in the prediction model the impact of the factors was very necessary.