Research On The Internal Force Redistribution Of Continuous Composite Girder With Corrugated Steel Webs

Based on a three span composite model girder with corrugated steel webs,the mechanical characteristics under elastic and ultimate bearing conditions are tested.The finite element method has been used to calculate and analysis the properties of the internal force redistribution mechanism considering the influence factors such as the strength of concrete and rebar,reinforcement ratio of normal steel and prestressed strand,the shear stiffness and the thickness of webs.The influence rules of these factors to the bending moment amplitude modulation coefficient are analyzed as well.The main progress and conclusions are as follows.(1)The results of the intermediate symmetrical loading test and eccentric loading test in elastic state indicated that the strain of the top and bottom flange is in accord with the planar section assumption,whereas the shear stress of webs distributed uniformly.It can be considered that the concrete flanges bears the axial force and the webs bear shear force only.The results of the eccentric loading test in elastic state indicated that the displacement on the load side is greater than the opposite side,while the strain on the top flange presents the opposite law due to the influence of warping stress(2)During the ultimate failure test,crack presented in the middle span firstly,and then the cross section of the middle support cracked.The yield load as well as the ductility and plastic rotation capacity of the section was increased with the increase of reinforcement ratio while the cracking load was basically same.Besides,the ultimate bearing capacity was enhanced and the degree of internal force redistribution was more sufficient.During the statistical process of cracks,it was found that the development of crack was closely related to reinforcement ratio of cross sections.The improvement of the reinforcement ratio inhibited the development of cracks width,which improved the crack resistance of the structure.(3)The results in the finite element numerical simulation indicated that with the improvement of concrete strength,the bearing capacity improved while the bending moment amplitude modulation coefficient decreased.With the increase of rebar strength,the capacity of beam increase slightly as well as the bending moment amplitude modulation.The increase of the reinforcement of flanges can both increase the capacity and moment amplitude,whereas the ratio in the top flange affects more.The shear stiffness influence the capacity a lot but there is no effects on the internal force redistribution.What's more,the thickness of webs has no effects on the capacity and the moment amplitude when the web is thick enough.The increase of the prestressed strand will make the internal force redistribution increase firstly,then decrease,and improve the load-bearing capacity of the girder greatly.