Buckling Behaviour of Stainless Steel Square Hollow Sections

2016 ◽  
Vol 853 ◽  
pp. 301-305
Author(s):  
Shameem Ahmed ◽  
Mahmud Ashraf ◽  
Mohammad Anwar-Us-Saadat
Keyword(s):  
Stainless Steel ◽  
Strain Hardening ◽  
Cross Sections ◽  
Design Method ◽  
Numerical Models ◽  
Slenderness Ratio ◽  
Design Guidelines ◽  
Material Nonlinearity ◽  
Cross Sectional ◽  
Steel Design

Structural stainless steel design guidelines should appropriately recognise its characteristic beneficial properties such as material nonlinearity and significant strain hardening. The Continuous Strength Method (CSM) exploits those through a strain based approach for both stocky and slender cross-sections. In this paper, a new design method is proposed that combines the CSM with Perry type buckling curves. Numerical models were developed to investigate effects of various parameters on column strength and to develop full column curves. It was observed that material nonlinearity significantly influence column strengths, and hence, different column curves were developed for a total of 20 material property combinations by calibrating imperfection factor and limiting slenderness ratio for each set. Proposed method includes the strain hardening benefits for stocky section, and abolished the necessity of calculating effective cross-sectional properties for slender sections. Performance of the proposed technique is compared against those obtained by the Eurocode EN1993-1-4.

scholarly journals Performance Optimization of Polymer Fibre Actuators for Soft Robotics

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 454 ◽  
Author(s):  
Ivan D. Rukhlenko ◽  
Syamak Farajikhah ◽  
Charles Lilley ◽  
Andre Georgis ◽  
Maryanne Large ◽  
...  
Keyword(s):  
Cross Sections ◽  
Performance Optimization ◽  
Analytical Calculation ◽  
Design Guidelines ◽  
Soft Robotics ◽  
Positive Pressure ◽  
Cross Sectional ◽  
Bending Angle ◽  
Pneumatic Actuators ◽  
Wide Range

Analytical modeling of soft pneumatic actuators constitutes a powerful tool for the systematic design and characterization of these key components of soft robotics. Here, we maximize the quasi-static bending angle of a soft pneumatic actuator by optimizing its cross-section for a fixed positive pressure inside it. We begin by formulating a general theoretical framework for the analytical calculation of the bending angle of pneumatic actuators with arbitrary cross-sections, which is then applied to an actuator made of a circular polymer tube and an asymmetric patch in the shape of a hollow-cylinder sector on its outer surface. It is shown that the maximal bending angle of this actuator can be achieved using a wide range of patches with different optimal dimensions and approximately the same cross-sectional area, which decreases with pressure. We also calculate the optimal dimensions of thin and small patches in thin pneumatic actuators. Our analytical results lead to clear design guidelines, which may prove useful for engineering and optimization of the key components of soft robotics with superior features.

Design of cold-formed compression web members with periodically varying section properties

2007 ◽  
Vol 34 (2) ◽  
pp. 253-265
Author(s):  
Serge Parent ◽  
Joseph J Pote ◽  
Kenneth W Neale
Keyword(s):  
Cross Sections ◽  
Design Method ◽  
Design Procedure ◽  
Effective Length ◽  
Cross Sectional ◽  
The North ◽  
Stub Column ◽  
Flexural Torsional Buckling ◽  
Open Face

In this paper, a design procedure for cold-formed channels periodically closed on their open face and utilized as joist web members is detailed. The design method for periodically closed sections is based on the representation of the cross-sectional properties using Fourier series introduced in Timoshenko quotients for the determination of the buckling loads about each of the three member axes. Once those loads are computed, they are used in the current framework of the North American Specification for the design of cold-formed structures with appropriate effective length coefficients. The proposed design methodology is compared with test results obtained from 36 stub column samples and 21 full-scale joist specimens, also presented in this paper.Key words: cold-formed struts, periodically varying cross sections, steel joists, flexural–torsional buckling, effective length coefficients.

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.

COMPRESSION CAPACITY OF SLENDER STAINLESS STEEL CROSS-SECTIONS

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Shameem Ahmed ◽  
Mahmud Ashraf
Keyword(s):  
Stainless Steel ◽  
Elastic Deformation ◽  
Cross Section ◽  
Cross Sections ◽  
Current Knowledge ◽  
Design Guidelines ◽  
Deformation Capacity ◽  
Post Buckling ◽  
Steel Sections ◽  
Definition Of

The Continuous Strength Method (CSM) is a new strain based design approach developed for nonlinear metallic materials, and has recently been successfully used for stocky stainless steel sections for which the benefit of strain hardening is more pronounced. Typically available stainless steel cross-sections are quite slender, and their failure is dominated by local plate buckling before yielding showing significant post buckling, which does not allow the definition of cross-section deformation capacity currently adopted in CSM. In this paper, a concept of equivalent elastic deformation capacity is introduced for slender sections, and the scope of CSM is extended to predict capacities for slender cross-sections under compression. Design guidelines are proposed to calculate equivalent elastic deformation capacities for various cross-section types using the current knowledge of CSM, which is used to predict the ultimate section capacity when subjected to compression. The proposed rules are verified against all available test results, and are found to in good agreement with experimental evidence.

INFLUENCE OF STRAIN HARDENING ON THE BEHAVIOR AND DESIGN OF STEEL STRUCTURES

2011 ◽  
Vol 11 (05) ◽  
pp. 855-875 ◽  
Author(s):  
LEROY GARDNER ◽  
FACHENG WANG ◽  
ANDREW LIEW
Keyword(s):  
Structural Steel ◽  
Strain Hardening ◽  
Plastic Material ◽  
Design Method ◽  
Steel Structures ◽  
Material Model ◽  
Rigid Plastic ◽  
Cross Sectional ◽  
Present Generation ◽  
Indeterminate Structures

The present generation of international structural steel design codes treats material nonlinearity through simplified elastic-plastic or rigid-plastic material models. However, the actual stress–strain response of structural steel is more complex than this and features, in particular, strain hardening. Strain hardening refers to the increase in strength beyond yield because of plastic deformation. The influence of strain hardening on the behavior and design of steel structures is examined in this study through both the experimentation and the analysis of existing data, and a method to exploit the additional capacity that arises is outlined. Both determinate and indeterminate structures are considered. The proposed design method, referred to as the continuous strength method (CSM), is a deformation-based design approach employing a continuous relationship between cross-sectional slenderness and cross-sectional deformation capacity, together with a material model that allows for strain hardening. Comparisons are made between test results generated as part of the present study and collected from existing studies, and the predictions from the CSM and Eurocode 3 (EC3). For all cases considered, the CSM, through a rational exploitation of strain hardening, offers a more accurate prediction of observed physical behavior.

scholarly journals Validation of Stainless-Steel CHS Columns Finite Element Models

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1785
Author(s):  
Daniel Jindra ◽  
Zdeněk Kala ◽  
Jiří Kala
Keyword(s):  
Stainless Steel ◽  
Cross Sections ◽  
Numerical Models ◽  
Initial Imperfection ◽  
Material Model ◽  
Nonlinear Material ◽  
Geometric Imperfection ◽  
Local Loss ◽  
Aesthetic Appearance ◽  
Wide Range

Stainless-steel elements are increasingly used in a wide range of load-bearing structures due to their strength, minimal maintenance requirements, and aesthetic appearance. Their response differs from standard steels; therefore, it is necessary to choose a different procedure when creating a correct computational model. Seven groups of numerical models differing in the used formulation of elements integration, mesh density localization, nonlinear material model, and initial geometric imperfection were calibrated. The results of these advanced simulations were validated with published results obtained by an extensive experimental approach on circular hollow sections columns. With regard to the different slenderness of the cross-sections, the influence of the initial imperfection in the form of global and local loss of stability on the response was studied. Responses of all models were validated by comparing the averaged normalized ultimate loads and the averaged normalized deflections with experimentally obtained results.

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.

STABILITY BEHAVIOR AND DESIGN OF NONCONVENTIONAL COLD-FORMED STEEL STRUCTURES — RESEARCH REVIEW

2011 ◽  
Vol 11 (05) ◽  
pp. 903-927 ◽  
Author(s):  
LÁSZLÓ DUNAI ◽  
GÁBOR JAKAB
Keyword(s):  
Laboratory Tests ◽  
Method Development ◽  
Failure Modes ◽  
Design Method ◽  
Numerical Models ◽  
Steel Structures ◽  
Product Line ◽  
Research Review ◽  
Cross Sectional ◽  
Cold Formed Steel

In the paper, the methodology and main results of two research projects on nonconventional cold-formed thin-walled steel structures are presented. Laboratory tests, standard-based calculations, numerical models, and the connection of these to design method development are summarized. The implementation of the methodology is presented on two areas in detail: CompressionC-section members and a truss made of C-section members. The studied CompressionC-section members are of various cross-sectional arrangement and end- and lateral-supporting conditions. They consist of single or double asymmetric C-section members; in the latter case, either a back-to-back arrangement is applied or two sections are stuck in each other, forming a box-like closed section. The applied load is in each case compression with different eccentricities. Test arrangement, program, and results are presented; measured load-bearing capacities are compared to resistances calculated according to Eurocode 3, Part 1–3 where applicable, design rules for the cases not covered by the code are proposed. Trusses made of C-sections from the same product line are analyzed in the light of full-scale laboratory tests. EC3-based design formulae are derived for the failure modes obtained in the tests either by modifying existing application rules or by deriving new ones from these. Advanced numerical models of both structures are presented with focus on modeling imperfections, bolted connections, and joint rigidities.

scholarly journals PARAMETRIC STUDY ON THE LATERAL TORSIONAL BUCKLING OF STAINLESS STEEL I BEAMS WITH CLASS 4 CROSS-SECTIONS IN CASE OF FIRE

2016 ◽  
Author(s):  
Nuno Lopes ◽  
Pedro Gamelas ◽  
Paulo Vila Real
Keyword(s):  
Stainless Steel ◽  
Cross Sections ◽  
Elevated Temperatures ◽  
Numerical Study ◽  
Design Guidelines ◽  
Steel Grade ◽  
Steel Beams ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Steel Members

For predicting the behaviour of beams with thin-walled I sections, named Class 4 in Eurocode 3 (EC3), it is necessary to account for the occurrence of both local and lateral torsional buckling (LTB). These instability phenomena, which are intensified at elevated temperatures, should be accurately considered in design rules. The fire design guidelines for stainless steel members, given in Part 1-2 of EC3, propose the use of the same formulae developed for carbon steel (CS) elements. However, these two materials have different constitutive laws, leading to believe that the use of those formulae should be validated. This work presents a parametric numerical study on the behaviour of stainless steel beams with Class 4 I sections at elevated temperatures. The influences of several parameters such as stainless steel grade, loading type and cross section slenderness are evaluated, and comparisons between the obtained numerical results and EC3 rules are presented.

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