Techno Press
Techno Press

Structural Engineering and Mechanics
  Volume 84, Number 3, November10 2022 , pages 295-310
DOI: https://doi.org/10.12989/sem.2022.84.3.295
 


Shear lag effect of varied sectional cantilever box girder with multiple cells
Zengwei Guo, Xinliang Liu and Longjing Li

 
Abstract
    This paper proposes a modified bar simulation method for analyzing the shear lag effect of variable sectional box girder with multiple cells. This theoretical method formulates the equivalent area of stiffening bars and the allocation proportion of shear flows in webs, and re-derives the governing differential equations of bar simulation method. The feasibility of the proposed method is verified by the model test and finite element (FE) analysis of a simply supported multi-cell box girder with constant depth. Subsequently, parametric analysis is conducted to explore the mechanism of shear lag effect of varied sectional cantilever box girder with multiple cells. Results show that the shear lag behavior of variable box-section cantilever box girder is weaker than that of box girder with constant section. It is recommended to make the gradient of shear flow in the web with respect to span length vary as smoothly as possible for eliminating the shear lag effect of box girder. An effective countermeasure for diminishing shear lag effect is to increase the number of box chambers or change the variation manner of bridge depth. The shear lag effect of varied sectional cantilever box girder will get more server when the length of central flanges is shorter than 0.26 or longer than 0.36 times of total width of top flange, as well as the cantilever length exceeds 0.29 times of total length of box's flange. Therefore, the distance between central webs can adjust the shear lag effect of box girder. Especially, the width ratio of cantilever plate with respect to total length of top flange is proposed to be no more 1/3.
 
Key Words
    bar simulation method. mechanism. multi-cell box girder. shear lag effect. variable box-section girder
 
Address
Zengwei Guo: State Key Laboratory of Mountain Bridge and Tunnel Engineering, Chongqing Jiaotong University, Chongqing, 400074, China
Xinliang Liu, Longjing Li: School of Civil Engineering, Chongqing Jiaotong University, Chongqing, 400074, China
 

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