Research On Concrete Creep For Continuousgrider Bridge Camber Setting

In order to ensure the two folded cantilever end at the same level and make into a linear desired by the design elevation, setting up the reasonable camber is necessary in cantilever construction. Construction of the centre sill gravity and provisional load, the prestressed load, concrete creep, error will affect the prestressing camber. In these factors, creep has a great influence on the bridge and linear change caused by the concrete shrinkage is difficult to determine.The factors that affect concrete creep are many. Therefore it receive widespread attention.On the existing research results, this paper using MIDAS/Civil analysis software set up old Zhang bridge finite element model and analysis camber at each creep theoretical models generated. Simulated old zhang bridge modle camber construction in concrete creep, prestressed load, and load cradle. And studied the bridge camber variation at all of factors. Concluded as follows:(1) ACI creep coefficient prediction model predicted values is more accurately, predictive value in the vicinity of the pier is a little too small. The overall prediction of creep is basically consistent with the actual value. Chinese norms and CEB-FIP model predicts is a little small. At the time of the camber forecast, in addition to Chinese norms forecasts, also consider ACI prediction model for adjust the predicting.(2) Through the analysis of the model, the biggest boom in the construction of the state, deformation generated by concrete creep is closest to the vertical total deformation.So it is the primary consideration when setting camber construction.(3) Concrete creep still cause long girder bridge scratch.The bridge deflection will increase with the development and continuous time. The humidity, temperature will also affect the deflection. The more humidity, the small deflection; the small humidity,the lower torsion increases. Therefore, it is needed to establish a model consistent with the construction of environmental design, and consider the creep factors,in order to improve long-term reliability of the bridge.(4) Vertical prestressing losses and vehicle load is also an important factor affecting the bridge camber. Among them, the deflection of the roof longitudinal prestressing loss that occurs deformation is large than the floor prestressed loss of deflection. So in the camber settings, it is also need to give full consideration in order to make the cambe prediction more accurate.