Research On Elevation Control Of PC Continuous Girder Bridge

With the rapid development of Chinese highway and railway, more long-span bridges are needed to span great rivers and bays. PC continuous beam bridges emerged as required and have been developed in recent years. There are a few construction methods of PC continuous beam bridges. Among these methods, cantilever installation and cantilever casting are widely used. In order to make sure the bridges meet the needs of linear, the bridge linear control must be emphasized in cantilever construction process.In construction process, the elevation control is the key step for ensuring linear. However, the elevation control is uncertain because it is infulenced by a lot of factors such as temperature , construction loads, materials, construction technology and so on. Combining the practical project of Song Huajiang bridge in Tong He, this paper made research on elevation supervision and control technology. On the basis of summarizing the investigation actuality of elevation supervision and control inside and outside china, long-span continuous beam bridges elevation predictive model including GM(1,1) model, SCGM(1,1) model, DGM(2,1) model and Verhulst grey preditive model were established by grey theory. Combining the construction technology scheme, theory analysis and the model preditive result in every construction steps about Song Huajiang bridge, construction supervision and control scheme was proposed. According to the supervision and control scheme, the three steps elevations about movement, placing concrete and stressing prestressed wires of steel were measured and controled, by analysing and comparing predictive precision of every models, the predictive model which was fit for elevation supervision and control of long-span continuous beam bridges was developed. The elevation supervision and control of Song Huajiang bridge in Tong He indicated that the precision of GM(1,1) model is good, which can meet the needs of precision demands, and the conclusion in this paper can be used in construction control of the long-span continuous beam bridges and continuous rigid-frame bridges.