Abstract:

In order to accurately analyze distortion effect of supported curved steel box composite girders with corrugated webs （CSBCG-CSWs） and flexible diaphragms， in this paper the distortion warping displacement mode of CSBCG-CSWs was established based on the relationship between distortional warping displacement， bending-torsion coupled displacement and internal force of composite girder， and the potential energy of the additional distortion frame deflection caused by the bending-torsion coupled effect was derived. The anti-distortion stiffness of flexible diaphragms was solved by using virtual work principle. The distortion differential equation was established based on the energy variational method， and the influencing factors of CSBCG-CSWs distortion effect were analyzed. The results if the study show that the analytical solution in this paper was in good agreement with the experimental value and Abaqus numerical solution. Compared with the results without the intermediate diaphragm of plate-type， the maximum distortion bi-moment is reduced by 77.7%， 85.6% respectively when 1~2 passes intermediate diaphragm of plate-type are set. Compared with the results of setting intermediate diaphragms of X-type and K-type， the maximum distortion bi-moment is reduced by 25% when diaphragm of plate-type is set. The distortion effect caused by concentrated load is mainly affected by the presence or absence of diaphragms at the loading point. The uniform load can better reflect the overall distortion effect of the composite box girder with intermediate diaphragm. When the distortion stress ratio of the steel box composite girder with corrugated webs is controlled within 10% and 5% respectively， the intermediate diaphragm spacing needs to be satisfied： the straight steel box composite girder is less than 8m and 6m， and the curved steel box composite girder is less than 6m and 5m respectively，and distortion stress ratio can be reduced when the self-gravity load is taken into account. The increase of intermediate diaphragm thickness has no obvious enhance on suppressing effect the distortion effect of the straight and curved steel box composite girder with corrugated web when the thickness of the intermediate diaphragm of plane-type is more than 6mm. When the central angle increases from 0° to 28°， the distortional warping normal stresses of 1/4-span and 1/2-span cross-setions of CSBCG-CSWs increase by 74.6% and 87.4%， respectively.

Key words: bridge engineering, composite girder with corrugated steel web, variation calculus, distortion, diaphragm rigidity