Research On Construction Control Of Prestressed Concrete Continuous Girder Bridges

With the vigorous development of the highway and railway transportation in our country, the continuous girder bridges have its significant advantages of strong adaptability, mature design,construction technology and reasonable cost in the construction of Bridges, and widely used. Currently, the main construction methods of continuous girder bridges have stents cast-in-situ method, the cantilever method and cantilever construction method, pushing method, moving die carrier, large floating crane construction method and construction method, etc. The cantilever method which has the advantages of its low cost, strong adaptability in long-span prestressed concrete continuous girder bridge is widely used. At the same time, the increase of the cantilever construction process also complicate the displacement and internal force of bridge structure. To ensure the quality of construction and meet the design requirements, it is especially important to monitor each construction stage.This article refers to relevant data of the cantilever construction technology and construction control, and combines with the engineering example of Long Xi Gang bridge, researches construction control of prestressed concrete continuous girder bridge, the main contents of this paper are as follows:(1) It introduces the domestic and foreign development status quo of the construction technology and the characteristics of the cantilever construction, and expounds analysis theory and calculation method of the concrete continuous girder bridge construction control.(2) Applying Midas/Civil software to establish simulation model for the structural calculation, and concluding the theoretical stress and theoretical deflection of each construction stage.(3) To build elevation monitoring system according to the characteristics of the cantilever construction, collet the deflection deformation data of each construction stage, analyze the error between the measured values and the theoretical value, and identify and correct parameters, further adjust to the next piece of elevation level. The results show that the bridge structural line is fluent, no abrupt and meet the design requirements.(4) To analyze the stress data of the main control section A7, the results show that the stress measured values,,75.0cpcσ≤f,cpcσ≤70.0f, and the ratio between measured stress and theoretical value is 0.4 ~ 0.8, shows that stress distribution of each construction stage is normal.(5) To analyze the temperature-deflection-time test,and conclude the deflection change rule that caused by temperatural change. The test results show that the deflection caused by temperatural change and the outside temperature showed opposite change tendency, and the deflection caused by temperature has hysteresis; In addition, the greater the temperature change, the bigger the deflection of cantilever end, and the longer the cantilever length, the effects are more obvious. And fitting out temperature distribution curve of every moment on the direction of beam,s height, in order to estimate the deflection of 14 pieces each moment which caused by temperature, reduce influences of elevation observation because of different measuring time and temperature deflection. Therefore, it is careful to consider the effect of temperature on the main girder elevation in the construction process.