Study On Key Problems Of Concrete Cable-Stayed Bridges Base On Three Dimensional Analysis

The thesis states the technique level of concrete cable stayed bridges. Aiming atdeficiencies of existing design theories and associating with the practical projects, the3-D stress analysis for two types of girder sections and box section pylon is done. Themain contents are summarized as follows:1. The actual technique level and deficiencies of concrete cable stayed bridgesare discussed. The design theory frame of concrete cable stayed bridge is set up.2. The 3-D stress analysis is done for PK section and DP section girders. Theexisting Simplified calculating methods for girder effective flange width, eccentricload effect, cross beam and cross beam effective flange width are analysed andevaluated. The reasonable values of these parameters are gived out.3. The thesis demonstrates that the shear lag effect is superposed of momentshear lag effect and axial force shear lag. The shear lag coefficient is related to theratio of moment and axial force. The alterative law of shear lag coefficient with thechange of ratio of moment and axial force is presented. The shear lag distributing lawof concrete cable stayed bridge of floating system is studied. It is pointed out that theshear lag coefficient is mainly affected by the axial force and approachs to one withthe increase of axial force.4. The strut and tie model design theory is discussed in detail. The strut efficientstrength based on Chinese specification is deduced. The strut and tie model foranchorage zone of box section pylon is established. The prestress tendons aredesigned. The precision and reliability of this strut and tie model are verified by 3-Dsolid element simulation model.