Research On Several Problems In Construction Stage Of Long Multi-span PC Continuous Girder Bridge Of Haizi Lake

The Haizi Lake Bridge is currently the first double-length PC continuous girder bridge in China.Therefore,there are many key technologies that need to be studied and solved,such as the problem of bearing offset setting,expansion joint installation,the closure order,and stiff skeleton stress analysis.This paper mainly analyzes the construction stage of Haizi Lake Bridge,and then discussed the selection and installation of expansion joints.Finally,the stress analysis of the stiff skeleton is carried out under the temperature load.The main research contents are as follows:After the cantilever construction simulation analysis by Midas civil,it was found that the tensile stress appeared on the top of the box girder.After comparing the design documents,it is considered that the wet weight condition of the concrete was not considered in the design stage of the cantilever casting.Then increase the number of prestressed steel bundles and carry out various simulation analysis.The results show that no tensile stress appears in the whole section,which proves that the prestressing adjustment scheme is feasible.In the expansion joint setting,the temperature of closure determines the reference length of the beam.The analysis shows that as long as the temperature range of the closure is determined,the beam will not interfere with the abutment when warm up.Then conducted the parameter analysis of the factors affecting the contraction and creep displacement.Based on the displacement of 5-year shrinkage and creep displacement superimposed by extreme temperature,the end expansion device of Haizi Lake Bridge is selected as D100 steel comb plate expansion joint.Because of the influence of temperature and installation time on the actual installation of expansion joints,the beam end will have longitudinal displacement,so the pre-compression of expansion device is calculated.When the system is warming up,the temperature force generated in the stiffening skeleton of the closure segment is greater than the frictional resistance of the support.When the temporary restraint is released,the temperature force can be released.Then the space shell element model of ANSYS is established,and the strength after the calculation meets the requirements of Q235 steel specification.Finally,the eigenvalue buckling analysis of the stiff skeleton is carried out.After analysis,the buckling coefficient is larger than the standard value,which meets the stability requirements.