Simplified Calculation Method of Rib Deviator Based on Planar Frames

Abstract:

A simplified calculation method based on planar frames is proposed for mechanical analysis and reinforcement design of rib deviator. In the planar frame model, top deck, bottom deck and webs of box girder are represented by 3 dof beams, while the rib deviator is equivalent to vertical and horizontal girders. Longitudinal lengths of the top deck and webs can be set the same as the thickness of the rib deviator for its tiny effect on the analysis. Then the planar frame model can be treated as an upsidedown Tshape beam, so the longitudinal length of the bottom deck can be obtained by analogy of the effective distribution width of Tshape beam. Compared with spatial grid model and ANSYS solid model, the planar frame model has a good coherence with only 5%～20% error in most cases and the solutions are conservative. In the next part, the application results of the simplified calculation method to two practical bridge structures show that the realistic reinforcement amount of the rib deviator is much larger than that by theoretical solution. The simplified calculation method can also be applied to twolayer or multilayer ducts deviators.

Key words:external prestressing; deviator; planar frame; reinforcement design; simplified calculation method