Experiment And Research On Concrete Creep For Long Spans Continuous Rigid-Framed Bridge

Shrinkage and creep are the inherent time-dependent characters of concrete which belongs to a viscoelastic material. The shrinkage and creep of concrete structure have prodigious effect on bridge alignment and stress control during bridge construction. In the mean time, the problems such as pre-stress loss,bearing asymmetry sink,concrete box-beam deflection,box-beam web crack,structure stress re-distributing and so on, which cause bridge structure invalidation or lose function early while it works. For these reasons, accurate estimation and predication of the deformation and long-term deflection of long-span bridges with high piers which arise from the effect of shrinkage and creep is of high importance for engineering design,quality control and construction process.This thesis collected masses of information about concrete shrinkage and creep from both domestic and abroad as well as the newly research results on concrete shrinkage and creep. And based on it, The deeply discussion and analysis was carried out such as the theory of concrete shrinkage and creep,the nature of shrinkage and creep,the effect of load on shrinkage and creep. In order to calculate the bridge creep under the condition of construction the software of GQJS was used to create model. The calculate results were compared with the measured ones. Finally the GM model was used to forecast concrete creep.Through the foregoing research work, the major results are as follows:(1) Based on the GL 2000 model and the china academy of building research (1986) model the concrete creep was calculated and forecasted and then get the concrete creep formula (5-11) by the power-exponent function. The factor main include concrete age,load hold time,stress and temperature. It has credible precision to forecast concrete creep. The concrete creep computation provides the reference for the same type bridge during the construction process and working.(2) This article combined with the actual data,the formula (5-11) computing results and the model analysis results. Used the GM model to optimize and forecast the concrete creep which occurred on bridge piers and the pre-stressed box beam. The result indicated that use the formula (5-11) forecast model the computed results combined well with the actual ones.(3) Bridge pier concrete creep computation indicated that from the upper structure begin to construct to the bridge completely constructed 1000 days after, the left bridge 2~# pier (100meter). 3~#pier (139 meter) and 4~# pier (133 meter) respectively has the creep value is: 29millimeter, 36 millimeter, 33 millimeter; right bridge 5~# pier (112 meter), 6~#pier (142 meter) and 7~#pier (135 meter) respectively has the creep value is: 30 millimeter, 37 millimeter, 35 millimeter. It has provided the powerful basis for Ma Shui-he bridge on upper structure camber installation and ensure the bridge alignment.