Constrution Control Of Swivel Bridge Which Using Scaffold And Segmented Construction Technology And Study Of Key Issue

With the constant improvement of our country road transportation network andthe need for construction of three-dimensional transport urban road, in recent years,the swivel construction technology has been more and more widely used. Because ofits simple structure, convenient construction, mature technology and goodperformance across, T-rigid frame swivel bridge has been favored by bridgeengineers.Swivel bridge, especially those using scaffold and segmented constructiontechnology, often requires multiple construction phase and system conversion, inorder to achieve the design requirements of bridge statue, construction control hasbecome a very important aspect in construction process. This paper, relying onpractical engineering, made a comprehensive exposition of construction control.First, summarize the structural calculations in construction control process. Thestructural calculations is a combination of formal analysis and flip analysis todetermine the value of pre-camber, and to analysis and forecast section stress in theconstruction process. Research deduced that the value of pre-camber will bedifferent when the bridge use two different construction methods of cantileverconstruction and taking scaffold construction, and the later one is relatively large.After the completion of each construction phase, by monitoring the structure of thestate (including linear, stress, cross-sectional dimensions), ensure the safety of thebridge construction and the quality of the project. This type of bridge design have itsspecial nature, so this paper made a checking calculation of the section stress in theprocess of prestressed tension, and gave guidance programs of prestressed steel bars,which has certain significance for the same type bridges.In swivel construction, cast-in-place and assembling are used most. Thesegment length is determined mostly by engineering experience at present. Thispaper, from pre-camber settings, section stress, long-term shrinkage and creep of thebridge, prestressing loss and other aspects, made a comparative analysis ofconstruction program for different segments, getting some basis for determining the segment length in bridge construction.â‘ the longer segment length the larger thereserve of compressive stress on the section of the upper edge, and the better for thestructure.â‘¡The longer segment length, the smaller the secondary stress inducedby shrinkage and creep. Because the smaller segment length, the more of segmentnumber, the larger the difference of concrete age, and more obvious of the effects ofshrinkage and creep.â‘¢The longer segment length, the fewer segments, moreobvious of prestressed structural effect, the smaller the prestressing losses.â‘£Thelonger segment length, the higher the cost of the project. So during the bridge design,it is need to take full account of the impact of segment length on pre-camber settings,shrinkage and creep, and prestressed loss and make a good balance between cost andconstruction schedule.This paper discussed the unbalanced weight control during the swivel bridgeconstruction, analyzed and calculated the weighing experimental data of swivelsection on Beijing-Baotou separated railway overpass, getting the unbalanced torque,friction torque, static friction coefficient of ball joints and eccentricity of the rotatingbody. Beyond that, this paper also calculated and verified the eccentricity of thestructure using pier bottom stress. The results show that the value of the two testmethods is very close, indicating that the pier bottom stress can be used to test outthe structure eccentric as a simple way.