Evaluation of CSA S16-14 asymmetry parameter for singly-symmetric beams

2019 ◽  
Vol 46 (3) ◽  
pp. 230-235
Author(s):  
James C. Koch ◽  
Robert G. Driver ◽  
Yong Li ◽  
Michael Manarin
Keyword(s):  
Exact Solutions ◽  
Asymmetry Parameter ◽  
Steel Structures ◽  
Approximate Equation ◽  
Lateral Torsional Buckling ◽  
Current Standard ◽  
Torsional Buckling ◽  
Cross Sectional ◽  
Design Standard ◽  
Sectional Shape

The provisions in the Canadian design standard S16, Design of Steel Structures, for determining the lateral–torsional buckling capacity of unequal-flange I-shaped beams employ an asymmetry parameter, βx, that is a function of the cross-sectional shape. It has been observed that the approximate equation for this parameter in the standard can be highly inaccurate in some cases. A study was completed to compare the approximate values of βx to the exact solutions for 16 312 singly-symmetric I-sections and 188 standard WT-shapes from the CISC Handbook of Steel Construction. It is concluded that the current standard provides extremely variable results, but is generally conservative for use in design, with the exception of T-sections, as long as the larger flange is in compression. Recommendations for adoption into the next edition of the standard are provided.

scholarly journals A comparative study of beam design curves against lateral torsional buckling using AISC, EC and SP

2019 ◽  
Vol 15 (1) ◽  
pp. 25-32 ◽  
Author(s):  
Vera V Galishnikova ◽  
Tesfaldet H Gebre
Keyword(s):  
Steel Structures ◽  
Reduction Factor ◽  
Steel Beams ◽  
Steel Beam ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Vertical Loading ◽  
Beam Design ◽  
Overall Stability

Introduction. Structural stability is an essential part of design process for steel structures and checking the overall stability is very important for the determination of the optimum steel beams section. Lateral torsional buckling (LTB) normally associated with beams subject to vertical loading, buckling out of the plane of the applied loads and it is a primary consideration in the design of steel structures, consequently it may reduce the load currying capacity. Methods. There are several national codes to verify the steel beam against LTB. All specifications have different approach for the treatment of LTB and this paper is concentrated on three different methods: America Institute of Steel Construction (AISC), Eurocode (EC) and Russian Code (SP). The attention is focused to the methods of developing LTB curves and their characteristics. Results. AISC specification identifies three regimes of buckling depending on the unbraced length of the member ( Lb ). However, EC and SP utilize a reduction factor (χ LT ) to treat lateral torsional buckling problem. In general, flexural capacities according to AISC are higher than those of EC and SP for non-compact sections.

Numerical Investigation of Stainless Steel Welded I-Sections Subjected to Lateral-Torsional Buckling

2016 ◽  
Vol 853 ◽  
pp. 317-321
Author(s):  
Mohammad Anwar-Us-Saadat ◽  
Mahmud Ashraf ◽  
Shameem Ahmed
Keyword(s):  
Stainless Steel ◽  
Rational Design ◽  
Slenderness Ratio ◽  
Numerical Results ◽  
Maintenance Cost ◽  
Test Results ◽  
Structural Members ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Cross Sectional

Stainless steel is now widely used in construction as structural members in recognition to its unique beneficial properties such as corrosion resistance, higher strength and ductility, andnegligible maintenance cost. Recent research on stainless steel has seen development of rational design rules to predict cross-sectional resistances but still lacks in appropriate knowledge at the member level. The current paper investigates the lateral-torsional buckling (LTB) behaviour of welded stainless steel I sections. Available test results were used to develop and validate nonlinear finite element (FE) models. Limited experimental evidences were supplemented by a large number of reliable numerical results covering wider range of member slenderness ratio. All test and numerical results were used to investigate the performance of Eurocode EN-1993-1-4 and Australian code AS/NZS 4673 in predicting member resistances against lateral-torsional buckling.

scholarly journals Optimisation of Shear and Lateral–Torsional Buckling of Steel Plate Girders Using Meta-Heuristic Algorithms

2020 ◽  
Vol 10 (10) ◽  
pp. 3639 ◽  
Author(s):  
Celal Cakiroglu ◽  
Gebrail Bekdaş ◽  
Sanghun Kim ◽  
Zong Geem
Keyword(s):  
Cross Sections ◽  
Failure Modes ◽  
Heuristic Algorithms ◽  
Search Algorithm ◽  
Harmony Search ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Cross Sectional ◽  
Plate Girders ◽  
The Cross

The shear buckling of web plates and lateral–torsional buckling are among the major failure modes of plate girders. The importance of the lateral–torsional buckling capacity of plate girders was further evidenced when several plate girders of a bridge in Edmonton, Alberta, Canada failed in 2015, because insufficient bracing led to the lateral buckling of the plate girders. In this study, we focus on the optimisation of the cross-sections of plate girders using a well-known and extremely efficient meta-heuristic optimisation algorithm called the harmony search algorithm. The objective of this optimisation is to design the cross-sections of the plate girders with the minimum area that satisfies requirements, such as the lateral–torsional buckling load and ultimate shear stress. The base geometry, material properties, applied load and boundary conditions were taken from an experimental study and optimised. It was revealed that the same amount of load-carrying capacity demonstrated by this model can be achieved with a cross-sectional area 16% smaller than that of the original specimen. Furthermore, the slenderness of the web plate was found to have a decisive effect on the cost-efficiency of the plate girder design.

Analysis of Lateral Torsional Buckling Strength of Single Symmetric I Beam

2020 ◽  
Vol 846 ◽  
pp. 226-231
Author(s):  
Wei Hsun Hsu ◽  
Yu Xin Liu ◽  
Kun Ze Ho ◽  
Wei Ting Hsu
Keyword(s):  
Cross Sections ◽  
Bending Moment ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Cross Sectional ◽  
Buckling Strength ◽  
Difference Analysis ◽  
Beam Design ◽  
Plastic Phase ◽  
Strength Difference

This study evaluates the variation of the bending moment strength of the single symmetrical and double symmetrical I-beam design. This study compares the use of a double-symmetric I-section with a large, small flange, a single-symmetric I-section with a large compression and large tension flange. The study shows that the four sections have the largest wing strength with double-symmetric I-section, and the inelastic and elastic strengths are similar to those of the single-symmetric I-section, especially the elastic region is almost the same. In the plastic phase, the double symmetrical flanges have a high cross-sectional strength. In the inelastic phase, the intensity of two individual symmetrical sections of the same area is close to a double symmetrical section. The use of a single symmetrical I-beam can be preferred over a double-symmetric I-beam. This study provides a single-symmetric I-beam strength difference analysis, providing users with a variety of options for comparing cross-sections.

Lateral-torsional buckling of girders with class 4 web: Investigation of coupled instability in EC3-based design approach

2020 ◽  
Vol 23 (11) ◽  
pp. 2442-2457
Author(s):  
Noémi Seres ◽  
Krisztina Fejes
Keyword(s):  
Cross Sections ◽  
Slenderness Ratio ◽  
Limit State ◽  
General Definition ◽  
Ultimate Limit State ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Cross Sectional ◽  
Plate Buckling ◽  
Buckling Resistance

This article focuses on the lateral-torsional buckling resistance of girders with slender, class 4 cross-sections with a research aim to check the accuracy of the design resistance model of EN1993-1-1 and EN1993-1-5 on the coupled instability of lateral-torsional buckling and local plate buckling resistances. The current Eurocode-based design method considers in the effective cross-sectional resistance calculation that yield strength is reached in the extreme fibre of the cross-section, and the reduction factor [Formula: see text] related to local plate buckling is calculated based on this assumption. However, if lateral-torsional buckling occurs, maximum stress in the web can be significantly smaller at the ultimate limit state which is not considered in the effective cross-sectional resistance calculation. On the other side, EN1993-1-1 proposes to consider the effective bending moment resistance in the relative slenderness calculation of lateral-torsional buckling, which is in contradiction with the general definition of the relative slenderness ratio [Formula: see text], which should refer to the plastic resistance divided by the critical load of the structure. This article aims to check if the current Eurocode-based design rules need improvement and to check the effect of the above-mentioned specific issues on the calculated lateral-torsional buckling resistance. An extensive numerical research programme is executed to check and compare the lateral-torsional buckling resistance of class 3 (as reference) and class 4 cross-sections, and results are compared to Eurocode-based design models.

scholarly journals Experimental and Numerical Study on the Lateral-Torsional Buckling of Steel C-Beams with Variable Cross-Section

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 941
Author(s):  
Ida Mascolo ◽  
Mariano Modano ◽  
Antimo Fiorillo ◽  
Marcello Fulgione ◽  
Vittorio Pasquino ◽  
...  
Keyword(s):  
Cross Section ◽  
Numerical Study ◽  
Numerical Approach ◽  
Computational Effort ◽  
Experimental Results ◽  
Variable Cross ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Cross Sectional ◽  
Thin Walled

Metallic thin-walled beams with continuously varying cross-sections loaded in compression are particularly sensitive to instability problems due to lateral-torsional buckling. Such a phenomenon depends on several parameters, including the cross-sectional properties along the entire length, material properties, load distribution, support, and restraint conditions. Due to the difficulty of obtaining analytic solutions for the problem under consideration, the present study takes a numerical approach based on a variational formulation of the lateral-torsional buckling problem of tapered C-beams. Numerical simulations are compared with experimental results on the buckling of a physical model of at thin-walled beam with uniformly varying cross-section, with the aim of assessing the accuracy of the proposed approach. The good agreement between numerical and experimental results and the reduced computational effort highlight that the proposed variational approach is a powerful tool, provided that the geometry of the structure and the boundary conditions are accurately modeled.

scholarly journals Development of a computer program for the design of laterally unrestrained steel beams

2018 ◽  
Vol 16 (3) ◽  
pp. 465-474
Author(s):  
Oladimeji Olalusi ◽  
Tony Dirisu ◽  
Chinwuba Arum
Keyword(s):  
Computer Program ◽  
Steel Beams ◽  
Lateral Torsional Buckling ◽  
Design Standards ◽  
Torsional Buckling ◽  
Cross Sectional ◽  
Beam Section ◽  
The Difference ◽  
Principles Of Design ◽  
Comparison Of The Results

This study presents the design results of a C-sharp based computer program developed for the design of laterally unrestrained I-section steel beams. The program was developed based on the stipulations of BS 5950 and Eurocode 3 (EC3) design standards. Several sets of steel beam models having the same cross-sectional dimensions but different laterally unrestrained span lengths, were designed using the developed program, and the results were validated using an established software, Staad Pro. The design results obtained were found similar to the results obtained using Staad Pro. For a specific beam section with constant loadings, as the span length of the laterally unrestrained compression flange increases the buckling capacity reduces, thus the longer the beam, the more it is susceptible to lateral torsional buckling. Comparison of the results obtained using BS 5950 to those of EC 3 at different laterally unrestrained span lengths revealed that the areas of design sections obtained for BS 5950 are 21.5%, on the average, higher than those of EC3. Thus, beams with laterally unrestrained compression flange designed according to the requirements of EC 3 are more economical. The difference in results is because of the differences in the principles of design and measures used between the two standards.

Elastic critical moment for monosymmetric beams under linear moment gradients

2021 ◽  
Author(s):  
Wenbin Xie ◽  
Magdi MOHAREB
Keyword(s):  
Finite Element ◽  
Steel Structures ◽  
Theoretical Background ◽  
Regression Equations ◽  
Finite Element Analyses ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Double Curvature ◽  
Potential Use ◽  
Critical Moments

The present study documents some inconsistencies observed when applying the lateral torsional buckling provisions of the Canadian standards of steel structures to characterize the elastic critical moments for monosymmetric beams subjected to linear moment gradients. An overview of the underlying theoretical background is presented and the reasons behind the discrepancies observed between standard-recommended solutions on one hand, and theoretical/finite element solutions on the other hand are discussed. An improved solution is then developed by generating a parametric study based on finite element analyses and developing regression equations to estimate the critical moments for monosymmetric beams under linear moments inducing double curvature. The expressions are cast in a dimensionless form as a function of four parameters. The potential use of the proposed solution is subsequently illustrated through a design example.

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