Large Span Continuous Beam-Through Steel Truss Combination Bridge Construction Monitoring Research And Practice

As a new type of bridge structure, The continuous beam-through steel trussCombination Bridge not only can effectively reduce the concrete box girder height,promote the overall stiffness of Bridges, at the same time also has the good dynamiccharacteristics.The study of new bridge structure form of this kind of work at home andabroad is still in its infancy, there are many problems worth studying.Based on the Lanxi railway bridge which was the nation’s largest continuousbeam-through steel truss Combination Bridge with a mainspan of168meters, the mainwork of this paper in the construction monitoring are as follows:①Determined thecontents of the construction monitoring,optimize the constructionprocess of formal analysis method, conducted in-depth research in the selection ofconcrete shrinkage and creep model and established a set of relatively completemonitoring and control systemaccording to the actual situation.②Established the finite element model of the ontinuous beam-through steel trussCombination Bridge,analysed the linear change and stress distribution in theconstruction processof the main girder, compared the results of MIDAS to the CSB inorder to ensure that the resultsare reliable to guiding the construction.③Analysed the sensitivity of the bulk density, strength,elastic modulus,prestressedload, and the temperature parameters based on the MIDAS civil finite elementmodel.According to the results,Corresponding measures have bean taken to modify thestructure’s line shape and stress control variable structure.④This paper made a deep study of prestressing camber, proposed the method ofdeterming the vertical mold elevation,provided a reasonable estimate high value,observed the elevation points and amended the formwork’s theory elevation value torealize the construction control of the practical engineeringaccording to practicalengineering and considering various factors.At the same time, through the embeddedprecision of the next node plate’s control and the reasonable choice of the steel trussassemble scheme to ensure the accuracy of closed late steel truss.⑤Controled the stress at the key section of the main girderin the process ofconstruction, ensured the safety of the structure in the construction process. Analysisedthe shear lag effect of themain girder’s cross section at block2, The measured data andtheoretical verified that during the process of cantilever construction of section2 showed the positive shear lag and the roof and floor of the girder’s shear lag coefficientis1.1-1.4respectively, won’t appear too much local stress phenomenon.