Discussions On The Analysis Of Precast Abnormal Box-beam And Study On Its Mechanical Nature

With the rapid development of express highways in China in recent years, the overlaps of street networks are getting more and more complicated, various factors such as existing roads and railroads, grid etc have to be taken into consideration when building new bridges, and abnormal bridges are inevitably and widely adopted, under which condition the study on abnormal bridges is carried with very much necessity.This paper takes the precast abnormal box beam as the focus, for it is different with traditional precast small box beam, and has its specialty in the stress of bearing. The single-beam analysis may have some limitation, and the beam grillage analysis is the only applicable method, but the beam grillage analysis also has some problems when using such as the difficulty in the dividing of longitudinal beams, the selection of stiffness of beams and etc, and the improper selection of which may lead to inaccurate results. Therefore, this paper discussed the analyzing methods of precast abnormal box beams by using Midas Finite-element Software, and drew some conclusion for realistic reference. The specific study includes:A systematic discussion on the fundamental theories of beam grillage analysis, building the beam grillage model with Midas Finite-element Software, and discussed some problems on the use of beam grillage analysis, and discussed the impact of dividing of longitudinal beams, the position of modeling points, and the theoretic stiffness of beams and so on.Making comparative analysis between the beam grillage model and the plate element modle, to find out any differences in the bearing reaction, bending deflection and stress of each model under different working conditions, so as to verify the accuracy of the beam grillage model.Built the single-beam model by adopting the conception of lateral distribution coefficient, analyzed and compared the results of beam grillage model, and verified the differences between the single-beam model and the beam grillage model, and discussed the feasibility of conducting single-beam analysis on the precast abnormal box beam.