Static Performance Study On Irregular Concrete Box Girder Bridge

With the rapid development of expressway and main road, more interchanges will be built. At the joint of main structure and the ramp, irregular box girder that is tapered and curvature-changing is always adopted. Therefore, on account of the increasing application of irregular box girder in the bridge project of interchanges, the study of irregular box girder turns to be necessary.On background of the design proposal of some irregular box girder bridge, this dissertation aims at investigating the feasibility of using grillage analogy method to analyze irregular box girder, and focuses on the space response of the irregular box girder at some load conditions. Midas/Civil, a large-scale FEM software package is used to model and analysis. And the main content is as follows:1. The basic theory of grillage analogy method to module box girder is studied systemic, the principles that how to divide the grillage, how to calculate the constants for longitude beams and transverse beams, and how to deal with the results gotten by grillage analogy in box girder bridge are analyzed detailedly, and the reasonable principles are proposed.2. In order to investigate the feasibility and accuracy of grillage analogy method, the grillage model as well as the shell element FE-model is established, and the corresponding stress and displacement results from the two models are compared, then reaches the conclusion that the displacement results are in good agreement, and the normal stress results from grillage analogy method are acceptable from an engineering design standpoint.3. With the FEM software Midas/Civil the dissertation builds the computation model of some irregular box girder bridge in Qing Dao, calculates the distortion, internal force and the constraint reaction of bearings which produced by the action of dead load, system temperature, gradient temperature and pre-stressed load, summarizes the load effect rule by analyzing the estimated data, and puts forward the design process and principles of tendons based on grillage analogy method.4. The effects that the cross diaphragm rigidity, girder bending rigidity and girder torsional rigidity have on the mechanical performance of the irregular box are analyzed, some beneficial conclusions are obtained, and may be available for use in irregular box girder engineering designs.