A Review Paper on Finite Element Analysis on Lateral Torsional Buckling Behavior of I Beam with Web Opening Using ETABS Software

Abstract

The lateral-torsional buckling behavior of I-beams with web openings has been a topic of interest among structural engineers for many years. The presence of a web opening in the beam can significantly affect its strength and stiffness, making it more prone to buckling failure. Therefore, understanding the buckling behavior of I-beams with web openings is crucial for the design of steel structures. Finite Element Analysis (FEA) has become a widely used tool for investigating the behavior of structures under different loading conditions. In this study, FEA was used to analyze the lateral-torsional buckling behavior of I-beams with web openings. The software used for the analysis was ETABS, which is a widely used software for analyzing and designing buildings and other structures. The objective of the study was to investigate the effects of different web opening shapes, sizes, and locations on the buckling strength of the beam. The FEA simulations were validated using experimental data available in the literature. The study analyzed different types of web openings, such as circular, rectangular, and elliptical shapes, and various sizes and locations of the web opening along the beam span. The results of the study showed that the presence of a web opening significantly reduced the strength and stiffness of the I-beam, making it more susceptible to buckling failure. The location of the web opening had a more significant effect on the buckling behavior than its size and shape. The results of the FEA simulations were found to be in good agreement with the experimental data available in the literature, which validates the accuracy of the ETABS software in predicting the buckling behavior of I-beams with web openings.

Introduction

I. INTRODUCTION

In recent years, a great deal of design for both steel and composite beams with web openings. Among the benefits is the behavior of steel and composite beams is quite similar at web openings. It was found that the stress and the deflection values are higher when the web opening is provided near the support. Therefore, it is preferable to provide web openings in the predominant bending region. Besides that, by strengthening the plate with a 70mm offset and the thickness of the strengthening plate equal to the thickness of the flange, there is a reduction in stress ratio and deflection for the I section [1]. However, the behaviour of statically indeterminate castellated composite beams is more complex than that of simply supported beams [2]. This is because the instability effects of the castellated composite beam are subjected to the negative moment regions where the bottom compression flange is unrestrained. The restrained distortional buckling mode is a torsional distortional for shorter beam spans while for longer spans the buckling mode changes towards the lateral-distortional. Recently, there are two known types of open web beams: castellated beams with hexagonal openings, and cellular beams with circular web openings.

The recent increase in the usage of castellated and cellular beams highlights the need for additional research. Castellated steel beam which is fabricated from standard hot-rolled I-section has a lot of advantages such as aesthetic architectural appearance, ease of services through the web openings, optimum self-weight-depth ratio, economic construction, larger section modulus, and greater bending rigidity.

However, the castellation of the beam results in distinctive failure modes depending on the geometry of the beams, size of web openings, web slenderness, type of loading, quality of welding, and lateral restraint condition [4]. The potential failure modes comprise shear buckling of a web post, formation of flexure mechanism, lateral torsion buckling, formation of Vierendeel mechanism, rupture of welded joints in a web post, and compression buckling of a web post. Investigation of these failure modes was previously detailed by Kerdal and Netherco

A. Finite Element Analysis

Finite element analysis (FEA) is a computer-based method that is used to simulate the behavior of complex systems and structures under different loading conditions. It is widely used in engineering and scientific fields to predict the response of structures, components, and materials to various external stimuli. The basic idea behind FEA is to divide a complex structure or system into smaller, simpler parts or elements, which are then analyzed individually. These elements are typically represented mathematically as nodes and interconnecting elements or meshes. The behavior of each element is then determined by solving the mathematical equations that describe its physical response to the external loads and constraints. FEA is a powerful tool for predicting the behavior of structures and materials, as it allows engineers and scientists to analyze complex systems that would be difficult or impossible to study experimentally. It is also very flexible, as it can be used to analyze a wide range of materials and structures, from simple components to complex systems.

B. Web Opening

1. In every steel beam has a vertical section called the web, and horizontal sections at the top and bottom of the web called legs or flanges; web openings are often required to allow larger services to pass through, such as soil pipes, air conditioning ductwork, etc.
2. The web opening provided in steel beams generally are in the shape of circular, rectangular, hexagonal, square, and sinusoidal.

C. Lateral-torsional Buckling of I- Beam

Lateral torsional buckling is a phenomenon that occurs in un-restrained beams which have undergone bending. The internal compression and tension forces generated within the cross-section as a result of the bending contribute to this form of buckling. The compression half of the cross-section tends to buckle in a lateral direction, while the tension half tends to remain closer to the un-deformed location due to the restorative effects of the tension within it. The combined effects of the behaviour between the compression and tension portions of the cross-section result in a rotational and lateral displacement of the overall beam. Open sections and deep narrow sections bending about their major axis are more susceptible to lateral torsional buckling due to their low capacity against buckling in the horizontal direction under compression forces.

Lateral-torsional buckling can be avoided by properly spaced and designed lateral bracing. Bracing is usually assumed to be elastic and characterized by elastic stiffness. It is well known that an elastic lateral brace restricts partially the lateral buckling of slender beams and increases the elastic buckling moment. Accordingly, the effect of elastic lateral bracing stiffness on the inelastic flexural torsional buckling of simply supported castellated beams with an elastic lateral restraint under pure bending is investigated by previous researchers. The effect of bracing depends not only on the stiffness of the restraint but also on the modified slenderness of the beam

D. Result

The numerical analysis consists of two main models of I-beam with different types of web opening and without web opening. To study the buckling behaviour, five types of web opening models were derived by varying the shape of the web opening.

II. ACKNOWLEDGMENT

We have great pleasure in delivering the project on the topic “Finite Element Analysis on Lateral Torsional Buckling Behavior of I-Beam with web opening using E-Tab Software". This project has helped to express extracurricular knowledge with incredible help from the guide of our project Prof. P.R. Admile We would like to thank especially the HOD civil department Prof. R.B. Ghogare As well as staff members of the civil department, all of them very compassionate and went off their way to help. We would like to thank especially Prof. S.M. Kale, Project coordinator, for his timely help and guidance toward the successful completion of our project. We would like to thank especially to Dr. S.T Shirkande, Principal of S.B.P.C.O.E. INDAPUR, for his guidance toward the successful completion of our project

Conclusion

In the current analysis, the finite element analysis is used to investigate the lateral torsional buckling behavior of I-beam with and without web opening. Analysis results show that the size of the web opening has a slight effect on the buckling moment values. Furthermore, five shapes and three sizes of opening with 1.1m section length were used to find the optimum size and shapes of opening. The optimum size in this study is 0.5D due to the high values of the buckling moment compared with 0.6D and 0.7D. Therefore, the spacing-to-diameter ratio (S/Do) significantly affected the lateral torsional buckling of each model. It was noted that Chexagon has the highest buckling moment compared to other web opening shapes. Besides that, the differences in buckling moment values decrease when the opening becomes larger. However, I-beam without web opening has the highest buckling moments compared to C-hexagon.

References

[1] Finite Element Analysis on Lateral Torsional Buckling Behaviour of I-BEAM With Web Opening Fatimah De’nan, Fadzli Mohamed Nazri, Nor Salwani Hashim [2] Prakash, B.D., Gupta, L.M., Pachpor, P.D. and Deshpande, N.V. 2011. Strengthening of Steel Beam Around Rectangular Web Openings. International Journal of Engineering Science and Technology, 3, 1130-1136 [3] Gizejowski, M.A. and Salah, W.A. 2011. Numerical Modeling of Composite Castellated Beams. International Conference on Composite Construction in Steel and Concrete 2008 (Composite Construction in Steel and Concrete VI) [4] Ellobody, E. 2011. Interaction of Buckling Modes in Castellated Steel Beams. Journal of Constructional Steel Research, 67, 814-825

Copyright

Copyright © 2023 Prof. Pushkraj R. Admile, Akanksha K. Thorat, Arpita A. Deokar, Dnyanraj J. Chavan, Shishir P. Mane-Deshmukh. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.