| With the development of bridge construction technology in China,cantilever construction method has become the main construction method of prestressed concrete continuous beam bridge.For prestressed concrete continuous girder bridges,the use of the cantilever construction method has the advantages of low cost,utilization of navigation,and strong spanning ability.However,the formation of prestressed continuous girder bridges requires a complicated process,when the number of spans increases,As the span increases further,new problems follow.For example:how to avoid excessive stress on the section of the girder during construction;how to ensure that the bridge surface after closure is good;......,if these problems are not handled properly,they will probably be detrimental to the structure,so that the curve of the girder beam bottom will not be smooth and form a permanent defect,which will affect the appearance.Therefore,In order to solve these problems,the construction process must be monitored.This article combines the actual project Shijiazhuang City Heping Road elevated west extension of the main line bridge tenth continuous beam bridge,span combination of 51+88+51 m,the cross section form is a single tank three rooms,the use of cantilever pouring construction technology.This bridge uses Midas Civil 2015 to establish a finite element model of the beam element for calculation,and carries out simulation analysis of the construction process.Combined with the simulation analysis process of the finite element model,some sensitive parameters in the construction monitoring process are selected,and the structural weight is analyzed in detail.The degree of influence of several important parameters such as stiffness,prestressing tension control force,hanging basket load,concrete shrinkage and creep effect,provides the basis for parameter identification and correction for construction monitoring.For the cantilever cast large span prestressed concrete continuous girder bridge,the contents,methods and monitoring instruments for the construction monitoring of the bridge are determined.Based on the main influencing factors in the construction monitoring of the bridge,the structure analytical method and error adjustment theory of the construction control of the bridge are proposed.To sum up,the bridge uses a combination of closed-loop control method for predictive control methods,and the construction control structure calculation method is mainly analyzed by forward analysis method.Based on the above content,the entire construction process of the bridge is effectively monitored and controlled,with emphasis on stress and line shape monitoring.The stress,linear measurement point arrangement in the construction monitoring in the actual project,and its analysis principle,data analysis process and result are described in detail.Based on the construction errors found during the entire monitoring process,these construction errors are analyzed and the temporary support for the most unfavorable conditions are taken into account for the main construction errors(low temperature closure of closed section,pouring error of 11# block and closing section).The analysis shows that the prestressed concrete continuous girder bridge adopts the non-designed closing temperature which is lower than the design closing temperature to close the main girder.It is beneficial to the bridge structure.The factor is the error of unbalanced pouring of concrete,and it has the greatest influence on the structural line shape in the maximum cantilever state,and the effect of shortening(about 0.9m)of the cantilever prestressed steel beam on the top plate is negligible on the full-bridge line shape and stress;Under the condition of the maximum unbalanced bending moment,the stress and displacement of the temporary bearing and the temporary support all meet the construction requirements,so the error of the unbalanced pouring process of the 11# beam section also meets the requirements. |
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