Shear lag effect on stress concentration in simply-supported stiffened box girder

Yamaguchi, Eiki; Kittaka, Naoto; Maho, Buchit; Sukontasukkul, Piti

doi:10.1016/j.jcsr.2021.106715

Cited by 8 publications

(4 citation statements)

References 13 publications

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“…It is worth noting that the laws of the variation of the shear lag factor of two load cases 1 and 2 are different. It can confirm that the loading condition, which is not mentioned in the standard [2][3][4], is also one factor affecting shear lag [33,34]. Sapountzakis and Dikaros [40] analyzed the problem based on BEM with (Model B) and without (Model A) shear stress correction and compared with the result obtained from 3D solid simulation by FEMAP commercial software.…”

Section: Examplementioning

confidence: 82%

“…Dikaros and Sapountzakis [27] proposed an advanced beam theory to analyze the composite beam with arbitrary cross-section using the Boundary Element Method (BEM). Lewiński and Czarnecki [28] constructed the new first-order warping function, which integrated with the theories of Vlasov [22], El Fatmi [23,24], Kim and Kim [29], Librescu and Song [30], and Timoshenko [31,32] to compose the theories of straight elastic bars Some authors, Sa-nguanmanasak et al [33], Yamaguchi et al [34], developed the 3D model to examine the shear lag phenomenon. However, the solution using shell or solid elements is still not more flexible and computationally efficient than determining the stress on the cross-section by superimposition technique, 2D cross-section, and 1D beam element.…”

Section: Introductionmentioning

confidence: 99%

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Shear Lag Analysis due to Flexure of Prismatic Beams with Arbitrary Cross-Sections by FEM

Tran¹,

Navrátil²

2021

Period. Polytech. Civil Eng.

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This paper presents the use of a finite element method (FEM) to analyze the shear lag effect due to the flexure of beams with an arbitrary cross-section and homogeneous elastic material. Beams are constrained by the most common types of supports, such as fixed, pinned, and roller. The transverse, concentrated, or distributed loads act on the beams through the shear center of the cross-section. The presented FEM transforms the 3D analysis of the shear lag phenomenon into separated 2D cross-sectional and 1D beam modeling. The characteristics of the cross-section are firstly derived from 2D FEM, which uses a 9-node isoparametric element. Then, a 1D FEM, which uses a linear isoparametric element, is developed to compute the deflection, rotation angle, bending warping parameter, and stress resultants. Finally, the stress field is obtained from the local analysis on the 2D-cross section. A MATLAB program is executed to validate the numerical method. The validation examples have proven the efficiency and reliability of the numerical method for analyzing shear lag flexure, which is a common problem in structural design.

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Section: Examplementioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Shear Lag Analysis due to Flexure of Prismatic Beams with Arbitrary Cross-Sections by FEM

Tran¹,

Navrátil²

2021

Period. Polytech. Civil Eng.

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“…A variation of deflection in the transformed box beam for α equals ½ is depicted in Figure 3. Regardless of the singularity produced at the support, the end stress could be calculated based on the intersection of the y-axis and tangent at the point where abrupt variations of normal stresses begin in the graph [51]. Additionally, the stress factor variation at the web-flange junction and along the length is demonstrated in the Figure 4.…”

Section: Resultsmentioning

confidence: 99%

Effect of Outstanding Flanges on Stress Concentration in Box Beam

Sharma¹,

Singh²

2022

cea

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Background of the research: A conventional box-type structure is generally used in constructing the core/shear wall, internal frame, and steel box girders. Tube-in-Tube with single and multiple tubes reduces the shear lag effect and lateral deformation in a tall tubular structure. Purpose: However, the present study focuses on the behavior of a modified form of the conventional box beam, i.e., a box beam with outstanding flanges. Thus, this study analyzes a box beam with outstanding flanges and compares the shear lag effect (Stress concentration) and lateral deformation with a conventional box beam. Methodologies: The minimum potential energy principle is applied to analyze the models and validated with the finite element results. Principal results: The transformation is observed to be reducing the shear lag effect at the web-flange junction and lateral deformations of the beam. In addition, the transformation also controls stress reversal. The modification demonstrated in the present study is stiffer than the conventional box-type structure as a core/shear wall or internal frame. Major conclusions and contributions to the field: This modification may be an integral part of tall tubular buildings producing significantly lowered stress concentration and lateral deformation. The present study is also applicable to strengthening steel box girders. It is possible to extend the bottom plate with the outstanding flange to increase the load-bearing capacity or strengthen the existing steel box girder. Therefore, the transformed box beam can be utilized as an economical alternative in constructing tall tubular buildings and retrofitting the steel box girder bridge. It is convenient and straightforward as there is no need to stiffen any part of the core/shear wall or internal frame. Additionally, there is no need to remove elements from the existing girder or alter its dimensions. Add the remaining flange by welding or bolting it onto the bottom flange to extend it. Limitation of the study and future research: A different assumption of stress function can be used in the flange and web when an orthotropic membrane theory is adapted to analyze the frame tube structure.

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“…The method produces accurate results for uniform loading, but inaccurate results for point loading. As with point loading, finding accurate results using finite element analysis is also challenging [37]. In addition to the well-known approaches to analyzing box beams and composite girders, the energy method is very flexible and can be applied to varying loads and support conditions.…”

Section: Introductionmentioning

confidence: 99%

Analytical modeling of stress concentration in composite box girders

Sharma,

Singh,

Kumar

et al. 2024

Eng. Res. Express

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In several structures/structural forms, including box beams, T-beams, U-beams, box girders, and tubular buildings, the stress concentration caused by the shear lag effect reduces their load-resisting capacity. The energy method has been proven to be more effective in analyzing the shear lag effect in these structures. Utilizing the minimum potential energy principle, this study illustrates a simplified approach to assessing stress concentration in composite box girders. Based on boundary conditions and shear loading conditions, closed form solutions are obtained for normal stresses and deflection. The present research results are verified with finite element analysis results and literature, demonstrating the robustness of the methodology. A composite box girder can be analyzed using the present approach under any support and loading conditions, taking material properties into account. To increase composite box girders' load carrying capacity, additional layers of material are generally added to the flange. When retrofitting a box girder in this way, cross-sectional flexural rigidity is trivially improved. The additional layer of material on the flange of the box girder may reduce stress concentrations caused by the shear lag effect when it improves the shear flow capacity (SFC) of the flange. Shear flow parameter (Γ) measures flange shear flow capacity. The flange SFC increases significantly for a core/layer with a ratio of elastic modulus to shear modulus (Ec/Gc) up to 1.26. When Ec/Gc rises even further, the flange SFC decreases. A composite box beam may have enhanced flange stiffness, with cores/layers having Ec/Gc ratios up to 2.86 and stress concentrations similar to that of a box beam without a core/layer. In composite box beams with a low aspect ratio, considering only flexural deformation in the core/layer augments the stress concentrations significantly. Deflection and negative shear lag are reduced significantly when the composite box beam flange has a high SFC.

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Shear lag effect on stress concentration in simply-supported stiffened box girder

Cited by 8 publications

References 13 publications

Shear Lag Analysis due to Flexure of Prismatic Beams with Arbitrary Cross-Sections by FEM

Shear Lag Analysis due to Flexure of Prismatic Beams with Arbitrary Cross-Sections by FEM

Effect of Outstanding Flanges on Stress Concentration in Box Beam

Analytical modeling of stress concentration in composite box girders

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