analysis and design of cold-formed steel channels subjected

Analysis and design of cold-formed steel channels subjected

to combined bending and web crippling

Wei-Xin Ren a,*, Sheng-En Fang a,b, Ben Young c

a Department of Civil Engineering, Central South University, Changsha, Hunan Province 410075, People’s Republic of Chinab E.T.S.de Ingenieros Industriales, Universidad Politecnica de Madrid, Madrid 28006, Spain

c Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China

Received 15 July 2005; received in revised form 7 March 2006; accepted 20 March 2006

Available online 4 May 2006

Abstract

The channel failures due to combined bending and web crippling may occur at the highly concentrated interior loading when there is no load

stiffener in cold-formed thin-walled steel beams. This paper presents accurate finite element models to predict the behavior and ultimate strengths

of cold-formed steel channels subjected to pure bending as well as combined bending and web crippling. Both geometric and material

nonlinearities are considered in the finite element analysis. The nonlinear finite element models are verified against experimental results of cold-

formed steel channels subjected to pure bending as well as combined bending and web crippling. The finite element analytical results show a good

agreement with the experimental results in terms of the ultimate loads and moments, failure modes and web load-deformation curves thus

validating the accuracy of the finite element models. The verified finite element models are then used for an extensive parametric study of different

channel dimensions. The channel strengths predicted from the parametric study are compared with the design strengths calculated from the North

American Specification for cold-formed steel structures. It is shown that the design rules in the North American Specification are generally

conservative for channel sections with unstiffened flanges having the web slenderness ranged from 7.8 to 108.5 subjected to combined bending

and web crippling. It is demonstrated that the nonlinear finite element analysis by using the verified finite element models against test results is an

effective way to predict the ultimate strengths of cold-formed thin-walled steel members.

q 2006 Elsevier Ltd. All rights reserved.

Keywords: Bending; Cold-formed steel channels; Design specification; Finite element analysis; Interaction; Nonlinearity; Thin-walled structures; Web crippling

1. Introduction

The failure of cold-formed steel channels subjected to

combined bending and web crippling may occur when there is

no load stiffener in cold-formed steel beams under highly

concentrated interior forces. The cold-formed channels without

transverse stiffeners against such loading are more susceptible

to failure because of the added bending moment, which may

obviously reduce the ultimate web crippling strengths of

channels [1]. Cold-formed steel sections are usually thinner

than hot-rolled sections and have modes of failure and

deformation, which are not commonly encountered in normal

structural steel design, and so corresponding design specifica-

tions are required to provide a guideline for the design of

0263-8231/$ - see front matter q 2006 Elsevier Ltd. All rights reserved.

doi:10.1016/j.tws.2006.03.009

* Corresponding author. Tel.: C86 731 2654349; fax: C86 731 5571736.

E-mail address: [email protected] (W.-X. Ren).

URL: http://bridge.csu.edu.cn (W.-X. Ren).

cold-formed thin-wall structural members [2]. The design rules

used in the Australian/New Zealand Standard [3] and the North

American Specification [4] for cold-formed steel structures

subjected to combined bending and web crippling are empirical

in nature based on a limited number of specimens tested in the

laboratory, and thus the design rules are only applicable for a

specific range of web slenderness and material properties. As

the appearance of new materials and the improvement of cold-

forming techniques, the material strength and sheet thickness

of cold-formed steel channels could be increased. Thus, the

applicability of the design rules to the cold-formed steel

channels subjected to combined bending and web crippling

needs to be investigated.

For that purpose, a series of tests on cold-formed high

strength steel channels subjected to combined bending and web

crippling were carried out by Young and Hancock [5]. The web

slenderness of the tested channels was stocky ranged from 15.3

to 45.0. The tests were conducted under the loading conditions

specified in the Australian/New Zealand Standard [3] and

American Specification [6] for cold-formed steel structures.

Thin-Walled Structures 44 (2006) 314–320

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Fig. 2. Comparison of failure modes under pure bending.

bf

t

dx

y

ri

Fig. 1. Geometry and symbol definition of cross-section of channel specimen.

W.-X. Ren et al. / Thin-Walled Structures 44 (2006) 314–320 315

The test results demonstrated that the design strengths

predicted by these specifications were generally conservative

for the tested channels.

Several tools are available when considering the analysis

and design of cold-formed sections such as testing, classical

methods based on explicit solutions of the governing

differential equations, finite element method, and finite strip

method [7]. Among these methods, the finite element method is

mostly used in dealing with both geometrical and material

nonlinearities. Finite element analysis (FEA) of cold-formed

steel structures is increasingly important in engineering

practice for its relatively inexpensive and time efficiency

compared with laboratory experiments, especially when a

parametric study of cross-section geometries is involved [8].

Thus, the numerical investigation based on nonlinear finite

element method is an effective way to solve engineering

problems. The key of numerical investigation is that the

validity of the finite element model. The material and

geometric nonlinearities as well as the complex boundary

conditions bring the difficulty to establish an accurate finite

element model.

The objective of this paper is intended to present analysis

and design of the cold-formed high strength steel channels

subjected to combined bending and web crippling. The finite

element program ANSYSw [9] was used to develop accurate

nonlinear finite element models for the numerical analysis. The

3D finite element models were established based on the

measured material properties obtained from tensile coupon

tests where the material nonlinearity is taken into account. The

developed finite element models were carefully calibrated

against the tests of channel sections in terms of the ultimate

loads, failure modes and load versus web deformation curves.

The verified finite element models were then used for an

extensive parametric study for a wide range of channel

dimensions with the web slenderness (h/t) ranged from 7.8 to

108.5. The results obtained from the numerical investigation

were compared with design predictions. The structural

behavior of cold-formed steel channels in terms of strength

and stiffness is quantified rationally for general design.

Consequently, the study provides understanding to the

structural performance of cold-formed steel channels subjected

to combined bending and web crippling.

2. Description of laboratory tests

A test program described by Young and Hancock [5,10]

provided the experimental ultimate loads and moments, failure

modes, load versus web deformation curves and interaction

curves for cold-formed steel channels subjected to pure

bending, pure web crippling as well as combined bending

and web crippling. The channel specimens were tested using

the loading conditions specified in the Australian/New Zealand

Standard [3] and American Specification [6] for cold-formed

steel structures. The test specimens were cold-rolled from

structural steel sheets having a nominal yield stress of

450 MPa, a nominal thicknesses ranged from 4 to 6 mm, a

nominal depth of the webs ranged from 75 to 300 mm, and

a nominal flange width ranged from 40 to 90 mm. The web

slenderness (h/t) values ranged from 15.3 to 45.0. The cross-

section geometry and symbol definition of channel specimens

are as shown in Fig. 1.

The test arrangement of pure bending is shown in Fig. 2(a)

where two channel specimens were used to provide the

symmetric loading. Hinge and roller supports were simulated

by half rounds and Teflon pads. The simply supported

specimens were loaded symmetrically at two points to the

load transfer blocks within the span using a spreader beam. The

pure in-plane bending of the specimens can be achieved

between two loading points without the presence of shear and

axial forces. The displacement transducers were used to

record the vertical deflections and curvatures of the specimens.

The specimens were labeled according to the test types and

their cross-section dimensions. For example, the label

‘BT100!50!4’ stands for a pure bending test of the specimen

Fig. 3. Comparison of failure modes under combined bending and web

crippling.

Table 1

Nominal and measured material properties

Channel Nominal Measured

d!bf!t

(mm)

E

(GPa)

s0.2(MPa)

s0.2(MPa)

su(MPa)

3f(%)

75!40!4 200 450 450 525 20

100!50!4 200 450 440 545 20

125!65!4 200 450 405 510 23

200!75!5 200 450 415 520 24

250!90!6 200 450 445 530 21

300!90!6 200 450 435 535 23

W.-X. Ren et al. / Thin-Walled Structures 44 (2006) 314–320316

having a nominal overall depth of the web of 100 mm, an

overall flange width of 50 mm, and a plate thickness of 4 mm.

The test arrangements and test results of the pure web

crippling under interior-one-flange (IOF) loading condition are

detailed in Young and Hancock [10,11]. The test results of the

cold-formed steel channels subjected to pure bending and pure

web crippling under IOF loading are herein used to

nondimensionalise the channels subjected to combined

bending and web crippling. Fig. 3(a) shows the test

arrangements of the cold-formed steel channels subjected to

combined bending and web crippling. Two channel specimens

were bolted to load transfer blocks at the end supports and a

bearing plate was poisoned at the mid-length of the specimens.

Hinge and roller supports were also simulated by half rounds

and Teflon pads. In addition, restraining frames were utilized to

prevent out-of-plane buckling of the long specimens. The web

deformations were measured between the bearing plate and the

bottom flanges of the specimens.

The loads were applied by means of bearing plate for the

combined bending and web crippling loading condition. They

were designed to act across the full flange widths of channels

excluding the rounded corners. The length of bearing (N) was

chosen to be the full and half flange widths of the channels. The

tests are detailed in Young and Hancock [5]. The specimens

were labeled such that the test type, web depth, interaction

factor and bearing length could be identified from the label. For

example, the label ‘C200K1.0N75’ defines the combined

bending and web crippling test specimen of 200 mm web depth

with an interaction factor of 1.0, and a bearing length of

75 mm. The pure bending test specimens had the same batch of

specimens as the web crippling tests as well as the combined

bending and web crippling tests. Hence, the material properties

of the test specimens for these tests were identical. Table 1

shows the material properties of the test specimens obtained

from tensile coupon tests.

3. Finite element modeling and analysis

3.1. General

The finite element (FE) package ANSYSw [9] was used in

this study to carry out the nonlinear finite element analysis and

simulate the tested cold-formed steel channels. It is aimed to

establish accurate finite element models for cold-formed steel

channels subjected to pure bending as well as combined

bending and web crippling. The FE models were calibrated

against the test data and performed an extensive parametric

study of channel geometries. The measured cross-section

dimensions, material properties and boundary conditions of the

tests were used in developing the FE models. The channel

sections of the FE models were based on the centerline

dimensions of the cross-sections together with the plate

thickness and rounded corners.

3.2. Element type and mesh

A thin shell element (Shell181 in ANSYS finite element

package) is used in the FE models. This is a four-node element

with six degrees of freedom at each node. The Shell181

element is suitable for thin to moderately thick structures with

powerful nonlinear capabilities such as large deflection, large

rotation, and large strain so that the web crippling deformation

and ultimate strength can be simulated. A 3D structural solid

element (Solid45) is utilized to model the load transfer blocks

and the bearing plates. The Solid45 element is suitable for the

3D modeling of structures with plasticity, stress stiffening,

large deflection, and large strain capabilities. The element is

defined by eight nodes having three translational degrees of

freedom at each node. The finite element mesh used in the

models has been investigated by varying the size of the

elements. The mesh sizes of approximately 15!15 mm or 9!9 mm (length by width) for both flange and web elements were

used to simulate the local deformation of channel web

crippling. The corresponding element aspect ratios (length-

to-width ratio) are chosen to be 1.0 for both flange and web of

the channel sections. A finer mesh is implemented at the

corners of channels due to its importance in transferring the

stress from flange to web. The typical finite element models of


cold-formed channels subjected to pure bending, and combined

bending and web crippling are shown in Figs. 2(b) and 3(b),

respectively.

3.3. Simulation of boundary conditions

The boundary conditions were carefully simulated in the FE

models. In the test setup, the channels were bolted to the load

transfer blocks. The coupled node method was herein used in

the region where the channel connected to the load transfer

blocks. The nodes at the x and y coordinates in the region were

coupled together by all degrees of freedom. For the regions

where the load applied through the bearing plates, the same

technique was implemented for the flanges connected to the

bearing plates. For the combined bending and web crippling

loading condition, the end load transfer blocks could only

rotate about the z-axis at the hinge support end, thus the nodes

on the z (vertical axis to web plane) symmetry axis of bottom

surface were restrained by x, y, z, rotx and roty five degrees of

freedom. As the load transfer blocks could also translate along

the x-axis at the roller support end, the translational degree of

freedom x was released in addition to the degree of freedom

rotz. The rest of the nodes were free to translate and rotate in

any directions.

3.4. Simulation of applied loading

The simulation of applied load in the finite element models

was identical to the tests. The displacement control method was

used. For the combined bending and web crippling loading

condition, the load was applied to the elements of the inner

strip at the flange corners. This is better than applying the

applied load on the bearing plate and then transferring the load

to the flange through contact elements [12]. For the pure

bending loading condition, the applied load was applied by

specifying a displacement to the two mid nodes at the top

surface of the load transfer blocks at the loading points. For the

interior-one-flange (IOF) loading condition of web crippling,

the model is detailed in Ren et al. [15].

3.5. Modeling of material properties

The measured material properties were used in the FE

models. The material properties of the test specimens were

determined by tensile coupon tests. The coupons were taken

from the center of the web plate of the untested specimens. The

tensile coupons were prepared and tested according to the

Australian Standard AS1391 [13] using 12.5 mm wide coupons

of gauge length 50 mm. Table 1 shows the material properties

of the test specimens.

The material of the channels behaves nonlinear when loaded

to the ultimate load-carrying capacity. The large strain

behavior of the material was implemented by using the

Isotropic Hardening material model. The material nonlinearity

behavior was herein incorporated with the true stress–strain

curve defined by true stress and logarithmic (true) strain

calculated from the coupon test data. The relationships

between true and engineering stresses or strains are given in

ANSYSw [9].

It should be noted that the cold-forming process enhances

the yield stress, but reduces the ductility of the material. This

influence is significant in the case of the corner material that the

yield stress increased by approximately 50% compared to the

flat material as shown in the tests conducted by Popovic et al.

[14]. Therefore, the corners material properties of the channels

were considered in the FE models. Ren et al. [15] detailed the

modeling of corners material properties of cold-formed steel

channels.

4. Verification of FE model

4.1. General

The FE models were verified against the experimental

results in terms of failure modes, web deformation, and

ultimate loads and moments. A nonlinear finite element

analysis by incorporating material nonlinearity was performed

using Newton–Raphson iteration method and displacement-

based convergent criterion.

4.2. Small strain and large strain

As mentioned earlier, the cold-formed steel channels

subjected bending, web crippling, and combined bending and

web crippling may experience large strains. Ren et al. [15]

investigated the effects of large strain on the web crippling

strength of the channels, where both small and large strain

analyses involved material nonlinearity were carried out. It is

shown that the small strain analysis slightly under-estimates

the web crippling strength of the channels, and the large strain

analysis provided a much better prediction of web deformation

and ultimate strength. Subsequently, the large strain analysis is

employed in the finite element analysis.

4.3. Failure modes

The failure modes of the cold-formed steel channels

subjected to pure bending as well as combined bending and

web crippling were simulated using the FE models. Figs. 2(b)

and 3(b) show the failure modes of the FE predictions for pure

bending, and combined bending and web crippling, respect-

ively. It is demonstrated that the FE predictions are in good

agreement with the failure modes observed from the tests.

4.4. Web deformation

Figs. 4 and 5 show the comparison of the web deformation

curves for channel specimens subjected to pure bending and

combined bending and web crippling, respectively. In general,

the web deformation curves predicted by the finite element

analysis agree well with the test curves. Therefore, the FE

models using large strain analysis are capable to predict the

web deformations of the cold-formed steel channels.

0 5 10 15 20 25 30 35 400

10

20

30

40

50

60

70

80

90

Test curveFEA curve

Mom

ent (

kNm

)

Web deformation (mm)

Fig. 4. Comparison of web deformation curves for specimen BT250!90!6

under pure bending.


4.5. Ultimate load-carrying capacity

The ultimate load-carrying capacities of moments [Mb-Exp

and Mb-FEA for channels subjected to pure bending are

shown in Table 2. The ultimate load-carrying capacities of

loads Pc-Exp and Pc-FEA as well as moments Mc-Exp and Mc-FEA

for channels subjected to combined bending and web crippling

are shown in Table 3.

The ultimate strengths predicted by the nonlinear FEA are

compared in Tables 2 and 3 with the experimental ultimate

strengths for pure bending as well as combined bending and

web crippling, respectively. The mean value of experimental-

to-FEA strength ratios Mb-Exp/Mb-FEA and Mb-Exp/Mb-FEA are

0.97 and 1.09 with the corresponding coefficients of variation

(COV) of 0.046 and 0.041 for pure bending, and combined

bending and web crippling, respectively. Fig. 6 illustrates the

moment-load interaction curves obtained from laboratory tests

with those predicted by the finite element analysis for different

size of channels subjected to combined bending and web

0 1 2 3 4 5 6 7 60

10

20

30

40

50

60

Web deformation (mm)

Loa

d (k

N)

Test curveFEA curve

Fig. 5. Comparison of web deformation curves for specimen C200K1.5N37

under combined bending and web crippling.

crippling. In most cases, the ultimate strengths of the channels

predicted by the nonlinear FEA are slightly less than the

experimental results, which indicate the FE predictions are

slightly conservative.

5. Parametric study

The calibrated FE models of the cold-formed steel


bending and web crippling were used to carry out an

extensive parametric study of different channel dimensions.

Twelve series of different channel sizes of cold-formed steel

channels were investigated with a wide range of web

slenderness h/t from 7.8 to 108.5. The channels for

parametric study have the plate thickness t of 4 and 6 mm

as well as the inside corner radius ri of 4 and 8 mm,

respectively. The overall depth of the web ranged from 75 to

450 mm, and the overall flange width ranged from 40 to

120 mm. The channel lengths were remained at 1270 mm for

the pure bending loading condition and ranged from 462 to

8590 mm for the combined bending and web crippling

loading condition. The bearing length (N) ranged from 20 to

120 mm, which was chosen to be the full and half flange

widths of the channels.

The total number of specimens in the parametric study is 12

for pure bending loading condition and 123 for combined

bending and web crippling loading condition. The finite

element analysis of cold-formed steel channels subjected to

pure web crippling has been carried out by Ren et al. [15]. In

the parametric study, the material properties of channels with

plate thickness of 4 mm are identical to those of the tested

channel section 75!40!4, and the channels with plate

thickness of 6 mm are identical to those of the tested channel

section 250!90!6 as shown in Table 1. The element aspect

ratio (length to width) of finite element mesh is approximately

1.0 for the flange and web of the channel sections. The element

meshes are 15!15 mm and 9!9 mm (length by width)

depending on the channel size. The loading method and the

boundary conditions of the parametric study are identical to

those used in the FE models calibration against the laboratory

tests.

6. Design rules

The design strengths obtained from the interaction equation

specified in the North American Specification (NAS) for cold-

formed steel structures [4] is used to compare with the

numerical results obtained from the parametric study for

channels subjected to combined bending and web crippling.

The design equation is empirical based on the limited test

results carried out by different researchers, where the

geometries and material properties of the tested channels are

limited. The design interaction equation specified in the NAS

Specification is herein further examined by the extensive

parametric study using finite element analysis. The unfactored

design strengths of channel sections having single unreinforced

webs were calculated using the following interaction equation

Table 2

Comparison of pure bending test strengths with FEA strengths

Specimen Web

d (mm)

Flanges

bf (mm)

Thickness

t (mm)

Radius

ri (mm)

Length

L (mm)

Exp. Ult. moment

per channel

Mb-Exp (kNm)

FEA moment per

channel

Mb-FEA (kNm)

Ratio

Mb-Exp/Mb-FEA

BT75!40!4 74.4 40.3 3.85 3.9 1267.9 6.44 6.68 0.96

BT100!50!4 99.2 50.4 3.83 4.1 1269.6 11.64 11.22 1.04

BT125!65!4 124.9 65.5 3.84 3.9 1269.2 16.20 16.51 0.98

BT200!75!5 198.8 75.9 4.70 4.2 1271.9 40.48 43.44 0.93

BT250!90!6 249.4 90.1 6.01 7.9 1269.5 79.90 80.28 1.00

BT300!90!6 298.7 91.2 6.00 8.4 1270.7 92.89 101.50 0.92

Mean 0.97

COV 0.046


for cold-formed steel channels subjected to combined bending

and web crippling,

1:07P

PFEA

� �C

M

MFEA

� �%1:42 (1)

The numerical results obtained from the parametric study

are plotted in Fig. 7 and the interaction curve of NAS

Specification are also plotted. For the purpose of comparison,

the design strengths have been nondimensionalised

with respect to the numerical results PFEA for pure web

crippling and MFEA for pure bending loading conditions.

Therefore, Pc-FEA/PFEA and Mc-FEA/MFEA were plotted for the

combined bending and web crippling as shown in Fig. 7. It can

be observed from Fig. 7 that the design strengths predicted by

the NAS Specification for channel sections with unstiffened

flanges are generally conservative.

Table 3

Comparison of combined bending and web crippling test strengths with FEA stren

Specimen Bearing

N (mm)

Web

d (mm)

Flanges

bf (mm)

Thickness

t (mm)

Radius

ri (mm)

Le

L (

C100K0.7N50 50.0 99.4 50.5 3.84 4.1 65

C100K1.0N50 50.0 99.6 50.5 3.83 4.1 89

C100K1.5N50 50.0 99.5 50.5 3.83 4.1 12

C100K0.7N25 25.0 99.4 50.5 3.84 4.1 66

C100K1.0N25 25.0 99.5 50.4 3.83 4.1 91

C100K1.5N25 25.0 99.5 50.4 3.84 4.1 13

C200K0.5N75 75.0 198.7 75.9 4.72 4.2 94

C200K1.0N75 75.0 198.8 75.9 4.71 4.2 18

C200K1.5N75 75.0 198.7 75.9 4.73 4.2 26

C200K0.5N37 37.5 198.4 75.8 4.71 4.2 97

C200K1.0N37 37.5 198.5 75.7 4.70 4.2 18

C200K1.5N37 37.5 198.6 75.7 4.72 4.2 26

C300K0.5N90 90.0 298.5 91.2 6.01 8.4 13

C300K1.0N90 90.0 298.5 91.2 6.01 8.4 26

C300K0.5N45 45.0 298.1 91.4 6.00 8.4 14

C300K1.0N45 45.0 298.2 91.3 6.01 8.4 28

Mean

COV

7. Conclusions

A nonlinear finite element analysis of cold-formed steel


bending and web crippling has been presented. The finite

element models have been verified against experimental

results. The failure modes, web deformations and ultimate

strengths of the channels have been simulated. The failure

modes predicted by the finite element analysis are in good

agreement with the failure modes observed in the tests for

pure bending as well as combined bending and web

crippling loading conditions. The ultimate strengths of the

channels predicted by the nonlinear finite element analysis

are generally agreed with the test results. The calibrated

finite element models were used to perform an extensive

parametric study for a wide range of channel dimensions

with unstiffened flanges having the web slenderness ranged

from 7.8 to 108.5. The ultimate strengths predicted by the

finite element analysis were compared with the design

strengths calculated using the North American Specification

gths

ngth

mm)

Exp. Ult. load per

channel

Ratio

Pc-Exp/

Pc-FEA

Exp. Ult. moment per

channel

Ratio

Mc-Exp

Pc-Exp

(kN)

Pc-FEA

(kN)

Mc-Exp

(kNm)

Mc-FEA

(kNm)

Mc-FEA

3.0 54.2 49.2 1.10 7.63 6.93 1.10

3.4 44.0 41.1 1.07 8.83 8.25 1.07

97.0 34.6 31.4 1.10 10.44 9.47 1.10

8.7 48.9 41.9 1.17 7.07 6.06 1.17

4.7 40.7 35.8 1.14 8.38 7.37 1.14

31.8 31.6 28.5 1.11 9.80 8.84 1.11

7.0 91.8 87.4 1.05 19.66 18.72 1.05

04.8 68.5 65.7 1.04 29.39 28.19 1.04

62.1 53.0 50.2 1.06 34.08 32.28 1.06

7.4 82.9 72.3 1.15 18.38 16.03 1.15

66.5 61.4 57.8 1.06 27.26 25.66 1.06

54.1 49.1 48.9 1.00 31.46 31.33 1.00

84.7 138.4 123.7 1.12 44.79 40.03 1.12

79.0 107.6 99.4 1.08 69.65 64.34 1.08

69.8 124.2 111.4 1.11 42.85 38.43 1.11

48.0 90.2 86.8 1.04 62.22 59.87 1.04

1.09 1.09

0.041 0.041

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Non

-dim

ensi

onal

ised

mom

ent,

M/M

Exp

Non-dimensionalised load, P/PExp

N=50.0mm (test) N=25.0mm (test) N=50.0mm (FEA) N=25.0mm (FEA) NAS 2001

(a) channel 100×50×4

Non

-dim

ensi

onal

ised

mom

ent,

M/M

Exp


(b) channel 200×75×5

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0


Non

-dim

ensi

onal

ised

mom

ent,

M/M

Exp


(c) channel 300×90×6

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0


Fig. 6. Test and FEA results for combined bending and web crippling.

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.10.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

Non

-dim

ensi

onal

ised

mom

ent,

M/M

FEA

Non-dimensionalised load, P/PFEA

FEA NAS 2001

Fig. 7. Comparison of FEA results with design curve for cold-formed steel

channels subjected to combined bending and web crippling.


for cold-formed steel structures for channels subjected to

combined bending and web crippling. It is observed that the

interaction equation specified in the North American

Specification are generally conservative for cold-formed

steel channels with web slenderness ranged from 7.8 to

108.5.

References

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analysis and design of cold-formed steel channels subjected

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