Stiffeners Design Of High Web For Steel-Concrete Composite Beam With Rotationally-Restrained

The concrete deck and steel girder of the steel-concrete composite beam bridge was connected with shear stubs,traditional plate stability theory is based on the theory of simply supported on four sides,the constraint effect on the web can’t be ignored.It seems unreasonable that take the traditional theory to analysis the local buckling behavior of high web for composite beam.With the change of the web plate boundary constraint stiffness,the stiffener location and stiffener stiffness on the web has also been changed.Using the traditional method of stabilizing and stiffening design methods cannot meet the design requirements of composite beam.The local buckling behavior of high web of steel-concrete composite beam mostly depends on rotationally-restrained support.A simplified calculation model with rotationally-restrained for calculating the local buckling of high web of composite beam under different loads was proposed,and formulas of critical buckling stress with Ritz energy method were also formed,and compared the results with classical theoretical results and the finite element results.Considering boundary deformation energy and combined variation calculation method in the simplified rotationally-restrained model,the calculation formula of the critical stress under the action of uniform compression,uneven compression,uniform shear and other load conditions was derived.Basing on the critical stress formula,considering the stiffeners deformation energy,the critical buckling stress formula of plate with rigid vertical ribs and flexible longitudinal ribs,transverse ribs rigid and flexible transverse ribs,as well as the plate with rigid transverse ribs and transverse ribs of the flexible plate were derived.The method of the distribution of the lateral and longitudinal stiffeners with the rotationally-restrained supported was proposed.Transverse stiffeners contains bearing stiffeners and intermediate stiffeners,bearing stiffeners needs to meet the materials strength requirements,Intermediate stiffener spacing is calculated mainly not considering the bending normal stress.Without considering the positive bending stresses,the district after stiffening grid need to meet the principle of safety equality.According to the web stiffening conditions and actual stress situation,the size limits in the case of the web prior to undermine the strength of the material does not occur stability damage was defined.Increasing of the rotational stiffness of the boundary led to increased web critical buckling stress,the self-stabilizing limit size of the web was also increased.