scholarly journals Experimental Study and Proposal to Improve the EWM Design of Cold-Formed Steel Lipped Channel Columns with Circular Holes under Axial Compression

2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Xingyou Yao
Keyword(s):  
Circular Hole ◽  
Axial Compression ◽  
Design Method ◽  
Local Buckling ◽  
Effective Width ◽  
Distortional Buckling ◽  
Channel Section ◽  
Circular Holes ◽  
Failure Loads ◽  
Cold Formed Steel

The cold-formed steel (CFS) lipped channel section with circular holes has been widely used in low-rise and multistory building structures as the column. However, the circular hole in the web makes the lipped channel column become susceptible to buckle. A total of 54 CFS lipped channel axial compression columns with and without circular holes were used to study the buckling behavior and the effective width design method. The interaction of the local buckling and the distortional buckling were observed for the short and intermediate columns, while the slender columns were controlled by the interaction of the local buckling, distortional buckling, and flexural buckling or flexural-torsional buckling. The experimental failure loads were gradually decreased with the increase in the diameter of the circular hole for the specimens with the same section. The failure loads of the specimens with two holes were lower than those of the specimens with one hole with same section and same diameter of holes. Then, the experimental results were used to validate a nonlinear finite element model (FEM) previously developed by the authors. The validated FEM was subsequently used to obtain additional 36 numerical failure results concerning the effects of the length, the section, and the diameter and the number of the circular holes. Furthermore, the proposal to calculate the distortional buckling coefficient of the CFS lipped channel section with circular holes were put forward based on numerical analysis considering the reduction of effect of holes. Finally, a proposal to improve the effective width method (EWM) design approach for CFS lipped channel sections with circular holes under axial compression was presented. The comparisons between experimental and numerical capacities and their calculations provided by the proposed EWM design method illustrate a great application of the proposed approach.

EWM-based design method for distortional buckling of cold-formed thin-walled lipped channel sections with holes

2022 ◽  
Vol 19 (1) ◽  
pp. 972-996
Author(s):  
Xingyou Yao ◽  
Keyword(s):  
Design Method ◽  
Effective Width ◽  
The Finite Element Method ◽  
Distortional Buckling ◽  
Buckling Strength ◽  
Channel Section ◽  
The North ◽  
Buckling Stress ◽  
Cold Formed Steel ◽  
Theoretical And Numerical Analysis

<abstract> <p>The distortional buckling is easy to occur for the cold-formed steel (CFS) lipped channel sections with holes. There is no design provision about effective width method (EWM) to predict the distortional buckling strength of CFS lipped channel sections with holes in China. His aim of this paper is to present an proposal of effective width method for the distortional buckling strength of CFS lipped channel sections with holes based on theoretical and numerical analysis on the partially stiffened element and CFS lipped channel section with holes. Firstly, the prediction methods for the distortional buckling stress and distortional buckling coefficients of CFS lipped channel sections with holes were developed based on the energy method and simplified rotation restrained stiffness. The accuracy of the proposed method for distortional buckling stress was verified by using the finite element method. Then the modified EWM was proposed to calculate the distortional buckling strength and the capacity of the interaction buckling of CFS lipped channel sections with holes based on the proposal of distortional buckling coefficient. Finally, comparisons on ultimate capacities of CFS lipped channel sections with holes of the calculated results by using the modified effective width method with 347 experimental results and 1598 numerical results indicated that the proposed EWM is reasonable and has a high accuracy and reliability for predicting the ultimate capacities of CFS lipped channel section with holes. Meanwhile, the predictions by the North America specification are slightly unconservative.</p> </abstract>

Experimental Study on Mechanical Behavior of Cold-Formed Steel Three Limbs Built-up Section Members

2010 ◽  
Vol 163-167 ◽  
pp. 651-654
Author(s):  
Tian Hua Zhou ◽  
Shao Feng Nie ◽  
Xiang Bin Liu ◽  
Guang Yi Li
Keyword(s):  
Experimental Study ◽  
Mechanical Behavior ◽  
Axial Compression ◽  
Local Buckling ◽  
Distortional Buckling ◽  
Torsional Buckling ◽  
Failure Characteristics ◽  
Compression Load ◽  
Cold Formed Steel ◽  
Flexural Torsional Buckling

18 specimens of cold-formed steel three limbs built-up section members are tested under axial compression load in this paper. The section forms are divided into two categories: A and B. Load-displacement (P-Δ) curves and failure characteristics of specimens are obtained. The results show that: As to section A members, the failure characteristics of LC, MC and SC series of specimens are flexural-torsional buckling, torsional buckling and distortional buckling, local buckling and distortional buckling. As to section B members, the failure characteristics of LC, MC series of specimens are flexural buckling, while local buckling and distortional buckling for members of SC series.

Comparison on Section Properties and Flexural Behaviour for Cold-Formed Steel Built-Up Section

2015 ◽  
Vol 735 ◽  
pp. 80-84 ◽  
Author(s):  
Yeong Huei Lee ◽  
Shahrin Mohammad ◽  
Yee Ling Lee
Keyword(s):  
Experimental Study ◽  
Local Buckling ◽  
Effective Width ◽  
Sectional Area ◽  
Flexural Behaviour ◽  
Distortional Buckling ◽  
Steel Sections ◽  
Cold Formed Steel ◽  
Flexural Resistance ◽  
Good Agreement

This paper performs analytical and experimental investigation on the section properties of locally produced cold-formed steel sections. Effective width method given by BS EN1993-1-3 is used to calculate the section properties for two slender cold-formed steel channel sections, namely KS200C20 and KS250C20. Local buckling and distortional buckling are taken into account in the calculation. Effective width method has significantly reduced the full sectional area and thus gives a relative lower value for the sectional resistance of cold-formed steel channel sections. The analytical results is compared to manufacturer’s data and differences of not more than 3.37% is recorded. Experimental study on the flexural behaviour on the two types of cold-formed steel channel sections is carried out. The results show that BS EN1993-1-3 has good agreement with experimental results for flexural resistance that included local and distortional buckling consideration. It is concluded that effective width method by BS EN1993-1-3 is suitable to calculate the section properties of of locally produced cold-formed steel channel sections.

Local buckling capacity of C-shaped cold-formed steel sections with punched webs

1984 ◽  
Vol 11 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Robert Loov
Keyword(s):  
Local Buckling ◽  
Effective Width ◽  
Test Results ◽  
Average Yield ◽  
Steel Sections ◽  
Load Tests ◽  
Cold Formed Steel ◽  
Stub Column ◽  
Best Fit ◽  
The Web

Load tests were carried out on 36 stub column samples of cold-formed steel studs having 38.1 mm wide × 44.5 mm long holes punched through their webs, steel thicknesses of 1.21–2.01 mm, and overall section depths of 63–204 mm. Based on these tests a best-fit equation for the effective width of the unstiffened portion of the web beside the holes has been developed. Suggested design equations have been proposed. The test results support the present equation for the average yield stress [Formula: see text] in Canadian Standards Association Standard S136-1974 but the present code equations for unstiffened plates are unduly conservative when applied to the design of the web adjacent to openings of the size considered.

scholarly journals Compression Test on Cold-Formed Steel Built-Up Back-to-Back Channels Stub Columns

2011 ◽  
Vol 201-203 ◽  
pp. 2900-2903 ◽  
Author(s):  
Chui Huon Tina Ting ◽  
Hieng Ho Lau
Keyword(s):  
Compression Test ◽  
Failure Modes ◽  
Local Buckling ◽  
Effective Width ◽  
Test Results ◽  
Direct Strength Method ◽  
Cold Formed Steel ◽  
Stub Column ◽  
Hot Rolled ◽  
Stub Columns

Built-up sections are used to resist load induced in a structure when a single section is not sufficient to carry the design load for example roof trusses. In current North American Specification, the provision has been substantially taken from research in hot-rolled built-up members connected with bolts or welds [1]. The aim of this paper is to investigate on built-up back-to-back channels stub columns experimentally and theoretically using Effective Width Method and Direct Strength Method. Compression test was performed on 5 lipped channel and 5 back-to-back channels stub columns fabricated from cold-formed steel sheets of 1.2mm thicknesses. The test results indicated that local buckling is the dominant failure modes of stub columns. Therefore, Effective Width Method predicts the capacity of stub columns compared to Direct Strength Method. When compared to the average test results, results based on EWM are 5% higher while results based on DSM are 12% higher for stub column.

C-section Cold-Formed Steel as Structural Members in Housing Construction in the Philippines

2019 ◽  
Author(s):  
Bernardo A. Lejano
Keyword(s):  
Axial Compression ◽  
High Speed ◽  
Failure Modes ◽  
Weight Ratio ◽  
High Strength ◽  
The Philippines ◽  
Bending Test ◽  
Housing Construction ◽  
Distortional Buckling ◽  
Cold Formed Steel

<p>Getting good lumber for housing construction is becoming difficult in the Philippines due to existing partial log ban. Although, the use of reinforced concrete is still the most popular in construction, an emerging alternative is the use of cold-formed steel (CFS). It is gaining popularity because of its high strength-to- weight ratio. However, information about the structural performance of locally-produced cold-formed steel is almost nonexistent. Although, design provisions are stipulated in the local Code, these are based on formulas developed abroad, hence the need to investigate these cold-formed steel. This study focuses on the C-section cold-formed steel, which is the most popularly used. The objective is to verify its performance when subjected to axial compression and flexure, both experimentally and computationally. For the computational part, the formulas stipulated in the National Structural Code of the Philippines were followed. For the experimental part, the cold-formed steel members were subjected to compression loads and flexural loads. Aside from usual sensors, high-speed cameras were used to capture the failure modes. For axial compression test, 80 specimens with different lengths and thicknesses were tested. For flexure, 24 specimens of back-to-back C-sections were subjected to 4-point bending test. Results showed the predicted strengths were well below the experimental values. In design, this means the use of Code-based formulas is conservative. Failure modes observed were torsional buckling and distortional buckling. Comparison of failure modes between experiment and computation shows 70% agreement for compression and 75% for flexure. Finite element method calculations were also done and were compared with experimental results.</p>

Optical Measuring Technique for the Investigation of Built-Up Cold-Formed Steel Structural Members

2011 ◽  
Vol 473 ◽  
pp. 343-351 ◽  
Author(s):  
Iveta Georgieva ◽  
Luc Schueremans ◽  
Guido De Roeck ◽  
Lincy Pyl
Keyword(s):  
Local Buckling ◽  
Structural Members ◽  
Distortional Buckling ◽  
Residential Housing ◽  
3D Motion Analysis ◽  
Vertical Displacements ◽  
Global Buckling ◽  
Cold Formed Steel ◽  
Thin Walled ◽  
Displacement Transducers

The construction industry uses cold-formed steel (CFS) sheets in the form of galvanised thin-walled profiles and corrugated sheets. In the past decade, CFS profiles have been competing with their hot-rolled counterparts as primary structural members of industrial halls, office buildings and residential housing of up to 3-4 storeys. The spans and column heights achieved with CFS profiles are ever larger. Due to the large slenderness of these members, adequate strength and stability are necessary, as well as reliability in design. Thin-walled members go through buckling during all stages of their working life. Local buckling appears at loads sometimes much lower than the design load. Distortional buckling seriously reduces the member resistance. It interacts with warping and lateral-torsional buckling, being significant for these asymmetric open sections. To restrict these effects, builders employ double sections - usually two standard cold-formed shapes bolted together to form a built-up section. These sections have the advantages of symmetry, higher stability and strength. The design of built-up members involves many uncertainties - although the European standard includes guidelines on the prediction of local, distortional and global buckling, the partial integrity and interaction between the parts of the composed members is still not studied. To study the actual behaviour, built-up members are tested in bending. An optical device for 3D motion analysis measures the displacement of points of interest on the specimen. Two interacting cameras use parallax to obtain the position of an arbitrary number of reflective markers glued to the specimen. The device tracks the movement of the markers in a 3D coordinate system without any contact with the specimen. Standard displacement transducers measure vertical displacements to validate the results. The paper gives an appraisal of the applicability of the method, a summary of the difficulties faced and the outcome of the test campaign.

scholarly journals Experimental Study and Direct Strength Method for Cold-Formed Steel Built-Up I-Sectional Columns under Axial Compression

2021 ◽  
Vol 2021 ◽  
pp. 1-22
Author(s):  
Xingyou Yao
Keyword(s):  
Finite Element ◽  
Axial Compression ◽  
Numerical Study ◽  
Experimental Results ◽  
Distortional Buckling ◽  
Cross Sectional ◽  
Direct Strength Method ◽  
Comparison Results ◽  
Cold Formed Steel ◽  
Interactive Buckling

The objective of this paper is to investigate the buckling behavior and design method of the ultimate strength for the cold-formed steel (CFS) built-up I-sectional columns under axial compression which failed in distortional buckling and interactive buckling. A total of 56 CFS built-up I-sectional columns subjected to axial compression were tested, and the different buckling modes and ultimate strengths were analyzed in detail by varying the thickness, the length, the spacing of screws, the end fastener group, and the cross-sectional dimensions of CFS built-up I-sectional columns. It was shown in the test that noticeable interaction of local and distortional buckling or interaction of local, distortional, and global buckling was observed for the built-up I-sectional columns with different lengths and cross-sectional dimensions. A finite element model (FEM) was developed and validated with experimental results. A further parametric study has been conducted including different cross sections and slenderness ratios for the built-up I-sectional columns. The load-carrying capacities obtained from the experimental and numerical study were used to investigate the feasibility of the current direct strength method (DSM) when DSM was applied to CFS built-up I-sectional columns. The comparison results showed that the current DSM is not safe for CFS built-up columns failed in distortional buckling and interactive buckling. Therefore, the improved design formulas were proposed, and their accuracy was verified by using finite element analysis (FEA) and experimental results of CFS built-up I-sectional columns subjected to axial compression.

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