An Analytical Method for Shear Lag Effect of Variable Section Box Girder
An analysis method and variable cross-section technology, applied in bridges, buildings, etc.
Active Publication Date: 2020-06-16
CHONGQING JIAOTONG UNIVERSITY
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Zhao Zhifeng et al. analyzed the shear lag effect of simply supported beams and cantilever beams using the analog rod method and compared them with the plexiglass model test solution and the finite element solution of the plate and shell. The results showed that the analog rod method had better calculation accuracy, but currently Most of the researches on analog rods focus on structures with equal cross-sections
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[0075] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
[0076] A method for analyzing the shear lag effect of variable cross-section box girders, specifically comprising the following steps:
[0077] S1: Using the equivalent rod model, the box girder model is equivalent to a structural system consisting of an ideal stiffener that only bears axial force and a thin plate that only transmits in-plane shear force between them. figure 1 The box girder shown is equivalent to figure 2 The stiffener-thin plate structure system shown (for the convenience of description, the upper and lower flange plates are equivalent to 9 and 5 stiffeners, respectively). The equivalent cross-sectional area of the ideal stiffener and the equivalent thickness of the thin plate are calculated based on the principle that the bending stress of the box girder top and bottom plate is equal;
[0078] Solve the equivalent t...
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The invention relates to an analysis method of shear lag effect of a variable cross section box girder, belonging to the technical field of bridge construction. The method includes the following steps: S1: the equivalent cross-sectional area of the ideal stiffener and the equivalent thickness of the thin plate are calculated by using the equivalent model of the analogous rod to equivalent the model of the variable cross-section box girder to the structural system consisting of the ideal stiffener only bearing the axial force and the thin plate only transmitting the in-plane shear force betweenthe stiffeners; S2: according to the equilibrium conditions and deformation compatibility conditions between the ideal stiffener and the wing plate, establishing the control equations of the shear lag effect; S3: calculating that horizontal shear flow at the junction of the web plate and the top plate of the variable cross-section beam, solving the control equation group of the shear lag effect,and obtaining the axial force of the stiffener which represents the bending normal stress in the wing plate; S4: calculating the shear lag coefficient of box girder by using the stiffener axial force.The invention provides a basis for reinforcement design and checking computation of the main beam by analyzing the distribution law of shear flow along the span length in the top plate and the web plate of the box beam with variable cross section.
Description
technical field [0001] The invention belongs to the technical field of bridge construction, and relates to a method for analyzing the shear lag effect of a variable-section box girder. Background technique [0002] When the thin-walled box girder undergoes bending deformation under the action of vertical load, the section of the box girder can no longer maintain the deformation of the plane section due to the influence of the shear deformation of the upper and lower flanges, resulting in the non-uniform distribution of the longitudinal bending normal stress of the flange along the cross section. Shear lag occurs. However, the current design method of girder bridges is still based on the analysis results of the bar system finite element software, and the reinforcement design and checking calculation are carried out for each member of the bridge structure according to the combined effect of different design load cases. Due to the limitations of the plane section assumption, t...
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IPC IPC(8): E01D2/04
CPCE01D2/04
Inventor 郭增伟李龙景张俊波王旭
Owner CHONGQING JIAOTONG UNIVERSITY