Study On Construction Control Of Long Span Prestressed Concrete Continuous Girder Bridges

Recent years, prestressed concrete continuous girder bridges develop vigorously inour country. At present, the construction methods chiefly have cantilever casts method,cantilever assembles method, simple becomes continuously method and the top pushesmethod. Among these methods, cantilever casts method and cantilever assemblesmethod have been used widely, this construction methods results in the complex changeof the inter forces and displacements in the bridge. Therefore, in bridge engineering, thereasonable selection construction method, correctly forecasting construct possess thevery important meaning in the bridge construction.Through the analysis and summary of the development of continuous beam and thedevelopment actuality of the construction control techniques in our country andabroad,the paper givers the study of the construction control techniques for long-spanpre-stressing concrete continuous beam bridge.According to its specia character of the construction control, the paperbringsforward are reasonable scheme of observation in the course of constructionconlrol, and establishes a comprehensive monitoring system.During the constructioncontrol of the west navigable bridge of Jin tang bridge, the system makes the structiondisplacement and stress of main section be acquired successfully.And throughMidas/civil software establishing the computer model,the thesis analyses the differencebetween theory and actuality, and discerns and changes parameters.Through analyzingcontrolling methods,the paper uses the method of the kalman’s filtering to forecastinflection of main beams,deflections. Provides each construction stage the formworkerection elevation, to guide the construction, based on the actual construction processmonitoring, the results showed that, the application of construction project and achievedgood results, and finishes the construction control of the west navigable bridge of Jin tang bridge.Through to the west navigable bridge of Jin tang bridge, the27、31main controlsection (roof) of the stress analysis of the data, the results show that the stress of themeasured value and the theoretical value was very close, ratio of0.55~1.12range,explain the basic normal stress distribution box girder.Temperature variation exerts great influence on the bridge alignment during thelong-span prestressed conerete continuos beam bridge consturetion.The longer thelength of main beam, the greater the deformation caused by sunshine temperaturedieffrenee.In order to find out the box girder section of difference in temperature andtemperature distribution in the section, by the time-temperature deflection test toobtain accurate temperature change on deflection effect law.The results of test show that,in the large span prestressed continuous beam bridge design and construction, thevariation in temperature is greater, the cantilever deflection is bigger, and the cantileveris long, the effect is obvious.Therefore, the change in temperature is the important factorto influence,should cause enough attention, should be considered in construction controlof main girder formwork elevation of temperature difference correction.The work done in this paper, provides us a technical support to learn more aboutthe structural characteristic of continuous beam bridge, control the constructionappropriately, guarantee the safety during bridge construction and ensure a reasonablecompletion ultimately. The researches of this paper can be used as a reference for theconstruction control of similar bridge in future.