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Steel and Composite Structures
  Volume 39, Number 4, May25 2021 , pages 435-451
DOI: https://doi.org/10.12989/scs.2021.39.4.435
 


Analysis of shear lag effect in the negative moment region of steel-concrete composite beams under fatigue load
Jinquan Zhang, Bing Han, Huibing Xie, Wutong Yan, Wangwang Li and Jiaping Yu

 
Abstract
    Shear lag effect was a significant mechanical behavior of steel-concrete composite beams, and the effective flange width was needed to consider this effect. However, the effective flange width is mostly determined by static load test. The cyclic vehicle loading cases, which is more practical, was not well considered. This paper focuses on the study of shear lag effect of the concrete slab in the negative moment region under fatigue cyclic load. Two specimens of two-span steel-concrete composite beams were tested under fatigue load and static load respectively to compare the differences in the negative moment region. The reinforcement strain in the negative moment region was measured and the stress was also analyzed under different loads. Based on the OpenSees framework, finite element analysis model of steel-concrete composite beam is established, which is used to simulate transverse reinforcement stress distribution as well as the variation trends under fatigue cycles. With the established model, effects of fatigue stress amplitude, flange width to span ratio, concrete slab thickness and shear connector stiffness on the shear lag effect of concrete slab in negative moment area are analyzed, and the effective flange width ratio of concrete slab under different working conditions is calculated. The simulated results of effective flange width are compared with calculated results of the commonly used specifications, and it is found that the methods in the specifications can better estimate the shear lag effect in concrete slab under static load, but the effective flange width in the negative moment zone under fatigue load has a large deviation.
 
Key Words
    steel-concrete composite beam; fatigue; shear lag; negative moment region; effective flange width
 
Address
Jinquan Zhang: Research Institute of Highway Ministry of Transport, Beijing, China
Bing Han, Huibing Xie, Wutong Yan and Jiaping Yu: School of Civil Engineering, Beijing Jiaotong University, Beijing, China
Wangwang Li: China Academy of Railway Sciences Corporation Limited, Beijing, China
 

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