Advances in Steel Structures - part 38 doc

350
B. Young and G.J. Hancock
formed steel structural members has increased rapidly. Up to the 1980s, the thickness of cold-formed
members was limited to 3 mm. This was due to the limitations of the cold-forming technology in the
past. In the 1990s, cold-formed members of 12 mm and greater thickness can be produced, and these
members are even thicker than some of the hot-rolled members. Therefore, the
thicker cold-formed
members may be used in place of the thinner hot-rolled members in building construction.
The purpose of this paper is first to investigate the use of hot-rolled steel structures standards in the
design of thicker cold-formed members. Therefore, a series of tests was conduced on cold-formed
unlipped channels subjected to major axis bending (pure flexure in-plane bending upon the application
of loads). The test results are compared with the design strengths predicted using the Australian
Standard (AS 4100, 1998) for hot-rolled steel structures. The second purpose of this paper is to
investigate the appropriateness of the section moment capacity design equations specified in the
current cold-formed steel structures standards and specifications for thicker cold-formed members.
The test strengths are compared with the design strengths predicted using the Australian/New Zealand
Standard (AS/NZS 4600, 1996) and the American Iron and Steel Institute (AISI, 1996) Specification
for cold-formed steel structures. Design recommendations are proposed for thicker cold-formed
channel members in this paper. In addition, the paper also presents a comparison between the
experimental results and the theoretical results of the cold-formed channel members. The theoretical
elastic and plastic bending moments were calculated based on the measured material properties and the
measured cross-section dimensions.
Figure 1" Definition of symbols
TABLE 1
MEASURED SPECIMEN DIMENSIONS FOR SERIES S 1
Specimen Web Flanges Thickness Radius Length
d t ri L
75x40x4-a
75x40x4-b
100x50x4-a
100x50x4-b

125x65x4-a
125x65x4-b
200x75x5-a
200x75x5-b
250x90x6-a
250x90x6-b
300x90x6-a
300x90x6-b
(mm)
74.4
74.4
99.2
99.2
124.9
124.9
198.8
198.8
249.5
249.3
298.5
298.8
bi
(mm)
40.3
40.2
50.3
50.4
65.5
65.5
75.9

75.9
90.1
90.0
91.2
91.2
(mm)
3.84
3.85
3.83
3.83
3.84
3.83
4.70
4.69
6.01
6.00
6.00
6.00
(mm)
3.9
3.9
4.1
4.1
3.9
3.9
4.2
4.2
7.9
7.9
8.4

8.4
(mm)
1268.0
1267.8
1269.9
1269.2
1269.2
1269.1
1272.4
1271.3
1269.2
1269.7
1269.8
1271.5
Note: 1 in. = 25.4 mm
Section Moment Capacity of Cold-Formed Unlipped Channels
TABLE 2
MEASURED SPECIMEN DIMENSIONS FOR SERIES 82
Specimen Web Flanges Thickness Radius Length
d t
ri
L
80x40x4-a
80x40x4-b
140x50x4-a
140x50x4-b
150•215
150•215
(mm)
80.3

80.4
140.0
140.2
149.4
149.3
b:
(mm)
39.7
39.6
49.9
50.1
75.6
75.5
(mm)
3.82
3.80
3.86
3.86
3.85
3.84
(mm)
4.0
4.0
4.0
4.0
4.0
4.0
(mm)
1202.0
1201.0

1251.0
1252.0
1050.0
1051.0
Note: 1 in. = 25.4 mm
351
EXPERIMENTAL INVESTIGATION
Test Specimens
The tests were performed on unlipped channels cold-formed from structural steel coils. Two series of
channels were tested, having nominal yield stresses of 450 MPa and 250 MPa for Series S1 and $2
respectively. The test specimens from the test Series S1 (called DuraGal) involve cold-forming of
steel sections followed by in-line galvanising. This process considerably enhances the yield stress of
the unformed material from 300 MPa to 450 MPa. The specimens were separated into two series of
different nominal yield stress. The Series S 1 and $2 consisted of nine different section sizes, having
the nominal overall depth of the webs (d) ranged from 75 mm to 300 mm, the nominal overall width of
the flanges
(by)
ranged from 40 mm to 90 mm, and the nominal thicknesses (t) ranged from 4 mm to 6
mm. The length of the specimens was chosen, such that the section moment capacity could be
obtained. Tables 1 and 2 show the measured specimen dimensions for the Series S1 and $2
respectively, using the nomenclature defined in Fig. 1. The specimens were labelled according to their
cross-section dimensions. For example, the label "75•215 defines the specimen having nominal
overall depth of the web of 75 mm, the overall flange width of 40 mm, and the thickness of 4 mm. The
last letter "a" indicates that a pair of specimens ("a" and "b") was used in the test to provide symmetric
loading for channel sections. The pair of specimens was cut from the same long specimen. Therefore,
the cross-section dimensions and the material properties of the pair of specimens were nearly the same.
Material Properties
The material properties of all specimens were determined by tensile coupon tests. The coupons were
taken from the centre of the web plate of the finished specimens belonging to the same batches as the
bending tests. The coupon dimensions conformed to the Australian Standard AS 1391 (1991) for the

tensile testing of metals using 12.5 mm wide coupons of gauge length 50 mm. The longitudinal
coupons were also tested according to AS 1391 in a 300 kN capacity MTS displacement controlled
testing machine using friction grips. A calibrated extensometer of 50 mm gauge length was used to
measure the longitudinal strain. A data acquisition system was used to record the load and the gauge
length extensions at regular intervals during the tests. The static load was obtained by pausing the
applied straining for one minute near the 0.2% tensile proof stress and the ultimate tensile strength.
This allowed the stress relaxation associated with plastic straining to take place. The material
properties determined from the coupon tests are summarised in Table 3, namely the nominal and the
measured static 0.2% tensile proof stress (or02), the static tensile strength (O'u) and the elongation after
fracture (eu) based on a gauge length of 50 mm. The 0.2% proof stresses were used as the
corresponding yield stresses (fy).
352
B. Young and G.J. Hancock
TABLE 3
NOMINAL AND MEASURED MATERIAL PROPERTIES
Test Series
Specimen
dxbf•
75x40x4
Nominal
0"0.2 =f~
(MPa)
450
0"0. 2 =f~
(SPa)
450
Measured
0-u
(MPa)
525

(%)
bl 20
S1 100x50x4 450 440 545 20
S1 125x65x4 450 405 510 23
S1 200x75x5 450 415 520 24
S1 250x90x6 450 445 530 21
300x90x6 450 435 535 23
80x40x4 250 280 370 35
140x50x4 250 290 380 39
S1
$2
$2
250
150x75x4
275
375
$2
37
Note: 1 ksi = 6.89 MPa
Figure 2: Schematic views of bending test arrangement
Section Moment Capacity of Cold-Formed Unlipped Channels
353
Figure 3" Bending test setup of specimens 200•215
354
B. Young and G.J. Hancock
Test Rig and
Operation
The schematic views of the general test arrangement are shown in Figs 2a and 2b for the elevation and
sectional view respectively. Two channel specimens were used in the test to provide symmetric
loading, and the specimens were bolted to the load transfer blocks at the two loading points and end

supports. 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. Half rounds and Teflon pads were also used at the loading points. In this
testing arrangement, pure in-plane bending (no shear) of the specimens can be obtained between the
two loading points without the presence of axial force. The distance between the two loading points
was 480 mm for the Series S 1 and $2, and the distance from the support to the loading point was 350
mm for the Series S1. Two photographs of the test setup of specimens 200x75x5 are shown in Figs 3a
and 3b for the elevation and end view respectively.
A 2000 kN capacity DARTEC servo-controlled hydraulic testing machine was used to apply a
downwards force to the spreader beam. Displacement control was used to drive the hydraulic actuator
at a constant speed of 0.8 mm/min and 0.6 mm/min for the Series S1 and $2 respectively. Three
displacement transducers were used to measure the vertical deflections and curvature of the specimens.
A SPECTRA data acquisition system was used to record the load and the transducer readings at regular
intervals during the tests. The static load was recorded by pausing for one minute near the ultimate
load. This allowed the stress relaxation associated with plastic straining to take place.
TABLE 4
COMPARISON OF EXPERIMENTAL RESULTS WITH THEORETICAL RESULTS FOR SERIES S 1
Specimen
dxbfxt
75x40x4
100•215
125•215
200•215
250•215
300•215
Experimental
Ult. Moment per
Channel
M Exp
(kNm)

6.44
11.64
16.20
Theoretical
Elastic
Me
(kNm)
5.50
9.53
14.80
Plastic
Mp
(kNm)
6.52
11.19
17.17
Comparison
Elastic
M Exp
Me
Plastic
M Exp
Mp
1.17 0.99
1.22 1.04
1.09 0.94
1.06 0.90
40.48 38.05 45.10
79.90 77.96 93.10 1.02 0.86
92.89 98.77 119.47 0.94 0.78

Mean
COV
Note: 1 in. = 25.4 mm; 1 kip = 4.45 kN
1.08 0.92
0.094 0.101
TABLE 5
COMPARISON OF EXPERIMENTAL RESULTS WITH THEORETICAL RESULTS FOR SERIES 82
Specimen
dxbfxt
80x40x4
140x50x4
Experimental
Ult. Moment per
Channel
M Exp
Theoretical
Elastic
Me
Plastic
Mp
Comparison
Elastic
M Exp
Me
Plastic
M Exp
M r
(kNm) (kNm) (kNm)
5.51 3.72 4.43 1.48 1.24
10.11

14.50
150•215 16.11
Note:
1 in. = 25.4 mm; 1 kip = 4.45 kN
1.20
12.13
16.53
Mean
COV
1.43
1.13 0.97
14.28
1.35
1.14
0.141 0.128
Section Moment Capacity of Cold-Formed Unlipped Channels
355
Test Results
The experimental ultimate moments per channel
(MExp)
for bending about the major x-axis are given in
Tables 4 and 5 for the Series 1 (nominal yield stress of 450 MPa) and Series $2 (nominal yield stress
of 250 MPa) respectively. The moments were obtained using a quarter of the ultimate static applied
load from the actuator multiplied by the lever arm (distance from the support to the loading point) of
the specimens. Out-of-plane bending was not observed in the tests.
COMPARISON OF EXPERIMENTAL RESULTS WITH THEORETICAL RESULTS
The experimental ultimate moments per channel
(MExp)
obtained for the Series S 1 and $2 are compared
with the theoretical elastic

(Me)
and plastic
(Mp)
bending moments, as shown in Tables 4 and 5. The
elastic and plastic bending moments were calculated using the measured yield stress (fy), as listed in
Table 3, multiplied by the elastic (Zx) and plastic
(Sx)
section moduli of the full sections respectively
for bending about the major x-axis
(Me =fy Zx
and
Mp = fy Sx).
The elastic and plastic section moduli
were calculated based on the measured cross-section dimensions as detailed in Tables 1 and 2.
The theoretical elastic and plastic bending moments are generally conservative for the Series S 1 and
$2, except that the plastic bending moments are unconservative for the Series S1 having the mean
value of the experimental to theoretical bending moment
(mExp/Mp)
ratio of 0.92 and a coefficient of
variation (COV) of 0.101, as shown in Table 4.
TABLE 6
COMPARISON OF TEST STRENGTHS WITH DESIGN STRENGTHS FOR SERIES S 1
Specimen
dxbfxt
Experimental
300x90x6
Ult. Moment per
Channel
Ml,:xp
(kNm)

9~.,
12.7
16.1
20.5
19.5
18.7
18.7
75x40x4 6.44
100x50x4 11.64
125x65x4 16.20
200x75x5 40.48
250x90x6 79.90
92.89
AS 4100
Section
Non-compact
Slender
Slender
Slender
Slender
Slender
Design
( M.,.x ) hot
AS/NZS 4600
& AISI
( M.,.x ) cold
Comparison
AS 4100
M Exp
(M.,.x)hol

(kNm)
5.50 1.10
8.92 1.31
12.52 1.49
33.32 1.39
70.57 1.28
90.18 1.17
1.29
0.110
Note: 1 in. = 25.4 mm; 1 kip = 4.45 kN
(kNm)
5.83
8.87
10.85
29.21
62.62
79.10
Mean
COV
AS/NZS 4600
& AISI
M Exp
(M.,.x )c,,la
1.17
1.30
1.29
1.21
1.13
1.03
1.19

0.086
TABLE 7
COMPARISON OF TEST STRENGTHS WITH DESIGN STRENGTHS FOR SERIES 82
Specimen
dxbfxt
Experimental
Ult. Moment per
Channel
M Exp
(kNm)
2~.,.
Design
80x40x4 5.51 10.0
140x50x4 14.50 12.9
150x75x4 16.11 19.6
Note: 1 in. = 25.4 mm; 1 kip = 4.45 kN
AS 4100
Section
Non-compact
Non-compact
Slender
( M.,. x ) h,,~
(kNm)
4.23
10.72
10.95
AS/NZS 4600
& AISI
( M.,. x ) cold
(kNm)

Comparison
AS 4100
M Exp
( M.,. x ) j,,,
3.72 1.30
10.11 1.35
12.26 1.47
Mean 1.37
COV 0.064
AS/NZS 4600
& AISI
M Exp
( M.,. x ) cord
1.48
1.43
1.31
1.41
0.062
356
B. Young and G.J. Hancock
COMPARISON OF TEST STRENGTHS WITH DESIGN STRENGTHS
The ultimate moments per channel obtained from the tests are compared with the section moment
capacity
(Msx)
for bending about the major x-axis predicted using the AS 4100 for hot-rolled steel
structures as well as using the AS/NZS 4600 and AISI Specification for cold-formed steel structures.
Tables 6 and 7 show the comparison of the test strengths
(mExp)
with the unfactored design strengths
(Msx)hot

and
(Msx)cota
for hot-rolled and cold-formed steel structures standards respectively. The design
strengths were calculated using the measured cross-section dimensions and the measured material
properties. The values of the section slendemess ()~) calculated according to the AS 4100 are also
given in Tables 6 and 7 for the Series S 1 and $2 respectively. The flanges of all channels were found
to be the most slender element of the cross-sections.
The design strengths predicted by the hot-rolled and cold-formed steel structures standards are
conservative for the Series S 1 and $2. The higher yield stress Series S 1 specimens are predicted less
conservatively than the lower yield stress Series $2 specimens. The cold-formed steel structures
standards are more accurate for predicting the section moment capacity for the Series S 1 having the
mean value of the test strength to design strength
(MExp / (Msx)cold)
ratio of 1.19 and a coefficient of
variation of 0.086, as shown in Table 6.
CONCLUSIONS AND DESIGN RECOMMENDATIONS
An experimental investigation of cold-formed unlipped channels subjected to major axis bending has
been presented. The tests were conducted on channel members having plate thickness up to 6 mm. The
test specimens have
thicker
plates than the traditional cold-formed thin gauge members. Two series of
channels having nominal yield stresses of 450 MPa and 250 MPa were tested. The experimental
results were compared with the theoretical elastic and plastic bending moments. It has been shown that
the theoretical bending moments are generally conservative for all channels, except that the plastic
bending moments are unconservative for channels having nominal yield stress of 450 MPa.
The test strengths were also compared with the design strengths obtained using the Australian Standard
(AS 4100, 1998) for hot-rolled steel structures as well as using the Australian/New Zealand Standard
(AS/NZS 4600, 1996) and the American Iron and Steel Institute (AISI, 1996) Specification for cold-
formed steel structures. It is demonstrated that the design strengths predicted by the hot-rolled and the
cold-formed steel structures standards and specifications are conservative for all tested channels.

Therefore, it is recommended that the section moment capacity design equations specified in the AS
4100, AS/NZS 4600 and the AISI Specification can be used for cold-formed channel members having
plate thickness up to 6 mm. The higher yield stress specimens are predicted less conservatively than
the lower yield stress specimens.
REFERENCES
American Iron and Steel Institute (1996).
Specification for the Design of Cold-Formed Steel
Structural Members,
AISI, Washington, DC.
Australian Standard (1991).
Methods for Tensile Testing of Metals,
AS 1391, Standards Association of
Australia, Sydney, Australia.
Australian Standard (1998).
Steel Structures,
AS 4100, Standards Association of Australia, Sydney,
Australia.
Australian/New Zealand Standard (1996).
Cold-Formed Steel Structures,
AS/NZS 4600:1996,
Standards Australia, Sydney, Australia.
Hancock, G.J., (1998).
Design of Cold-Formed Steel Structures
(To Australian/New Zealand Standard
AS/NZS 4600:1996), 3rd Edition, Australian Institute of Steel Construction, Sydney, Australia.
WEB CRIPPLING TESTS OF HIGH STRENGTH
COLD-FORMED CHANNELS
B. Young ~ and G.J. Hancock 2
School of Civil and Structural Engineering, Nanyang Technological University, Singapore 639798
(Formerly, Department of Civil Engineering, University of Sydney, Sydney, NSW 2006, Australia)

2 Department of Civil Engineering, University of Sydney, Sydney, NSW 2006, Australia
ABSTRACT
The paper presents a series of web crippling tests of high strength cold-formed unlipped channels
subjected to the four ioading conditions specified in the Australian/New Zealand Standard (AS/NZS
4600, 1996) and the American Iron and Steel Institute (AISI, 1996) Specification for cold-formed steel
structures. The four specified loading conditions are the End-One-Flange (EOF), Interior-One-Flange
(IOF), End-Two-Flange (ETF) and Interior,Two-Flange (ITF) loading. The web slenderness values of
the channel sections ranged from 15.3 to 45.
The test strengths are compared with the design strengths obtained using the AS/NZS 4600 and the
AISI Specification. It is demonstrated that the design strengths predicted by the standard and the
specification are generally unconservative for unlipped channels. Test strengths as low as 43% of the
design strengths were obtained. For this reason, new web crippling design equations for unlipped
channels are proposed in this paper. The proposed design equations are derived based on a simple
plastic mechanism model, and the web crippling strength is obtained by dispersing the bearing load
through the web. The proposed design equations are calibrated with the test results. It is shown that
the web crippling strengths predicted by the proposed design equations are generally conservative for
unlipped channels with web slenderness values of less than or equal to 45. The reliability of the
current design rules and the proposed design equations used in the prediction of web crippling strength
of cold-formed channels are evaluated using reliability analysis. The safety indices of the current
design rules for different loading conditions are generally found to be lower than the target safety
index specified in the AISI Specification, while the safety indices of the proposed design equations are
higher than the target value.
KEYWORDS
Bearing capacity, Cold-formed channels, Design strength, High strength steel, Plastic mechanism
model, Reliability analysis, Steel structures, Structural design, Test program, Test strength, Web
crippling, Web slenderness.
357
358
INTRODUCTION
B. Young and G.J. Hancock

Web crippling is a form of localized buckling that occurs at points of transverse concentrated loading
or supports. Cold-formed channels that are unstiffened against this type of loading are susceptible to
structural failure caused by web crippling. The computation of the web crippling strength by means of
theoretical analysis is quite a complex process as it involves a large number of variables. Hence, the
current design rules found in most specifications for cold-formed steel structures are empirical in
nature. The empirical design rules used in the Australia/New Zealand Standard (AS/NZS 4600, 1996)
and the American Iron and Steel Institute (AISI, 1996) Specification for cold-formed steel structures
were based on the experimental findings of Winter & Pian (1946), Zetlin (1955) and Hetrakul & Yu
(1978) for sections with slender webs. The four loading conditions that are of prime interest are
namely the End-One-Flange (EOF), Interior-One-Flange (IOF), End-Two-Flange (ETF) and Interior-
Two-Flange (ITF) loading.
Although, according to Nash & Rhodes (1998), the computation of web crippling strength obtained
using empirical methods is relatively rapid and safe within their range of application, this does not
imply that empirical methods are without drawbacks. The equations, derived through empirical
methods, are only applicable for a specific range and it may be difficult to ascertain the underlying
engineering principles in parts of the complex equations. Therefore, there is a need to determine the
appropriateness of the current design rules on the various types of steel members and to propose some
design equations that are derived through a combination of both empirical and theoretical analyses.
In this paper, the appropriateness of the current design rules in the AS/NZS 4600 and the AISI
Specification for unlipped channels subjected to web crippling is investigated. A series of tests was
conducted under the four loading conditions specified in the AISI Specification. The web crippling
test strengths are compared with the design strengths obtained using the AS/NZS 4600 and the AISI
Specification. A set of equations to predict the web crippling strengths of unlipped channels with web
slenderness (depth of the flat portion of the web to thickness ratio,
h/t)
values less than or equal to 45 is
proposed. The proposed design equations are derived based on a simple plastic mechanism model, and
these equations are calibrated with the test results. The proposed design equations are derived through
a combination of theoretical and empirical analyses. Factors to account for the variation of the web
slenderness of the channel sections have also been incorporated in the proposed design equations. In

addition, the current design rules and the proposed design equations used in the prediction of web
crippling strength are evaluated using reliability analysis. The safety indices of the current design rules
and the proposed design equations are compared with the target safety index specified in the AISI
Specification.
TEST
PROGRAM
A series of tests was performed on cold-formed unlipped channels subjected to web crippling. The
specimens were rolled from structural steel sheets having nominal yield stress of 450 MPa. The
sections (called DuraGal) have in-line galvanising which increases the nominal yield stress from 300
MPa to 450 MPa when combined with roll-forming. The test specimens consisted of six different
cross-section sizes, having a nominal thicknesses ranged from 4 mm to 6 mm, a nominal depth of the
webs ranged from 75 mm to 300 mm, and a nominal flange widths ranged from 40 mm to 90 mm. The
web slenderness
(h/t):
values ranged from 15.3 to 45.0, and these values were obtained using the
measured cross-sectional dimensions. The specimens are considered to have stocky webs. The
specimen lengths were determined according to the AS/NZS 4600 and the AISI Specification. Table 1
shows the nominal specimen dimensions, using the nomenclature defined in Fig. 1, where d is the
overall depth of web,
bf
is the overall width of flange and t is the thickness of the channels. Young and
Web Crippling Tests of High Strength Cold-Formed Channels
359
Hancock (1998) also performed similar tests on cold-formed channels having different web slendemess
and material properties. The web slenderness values ranged from 16.2 to 62.7, and had nominal yield
stress values of 250 MPa and 450 MPa.
The material properties of the test specimens were determined by tensile coupon tests. The coupons
were taken from the centre of the web plate of the finished specimens. The tensile coupons were
prepared and tested according to the Australian Standard AS1391 (1991) using 12.5 mm wide coupons
of gauge length 50 mm. The static load was obtained by pausing the applied straining for one minute

near the 0.2% tensile proof stresses and the ultimate tensile strength. This allowed the stress relaxation
associated with plastic straining to take place. Table 1 summarises the material properties determined
from the coupon tests, namely the nominal and the measured static 0.2% tensile proof stress (o02), the
static tensile strength (ou) and the elongation after fracture (cu) based on a gauge length of 50 mm. The
0.2% proof stresses were used as the corresponding yield stresses.
The load or reaction forces were applied by means of bearing plates. The bearing plates were
fabricated using high strength steel having a nominal yield stress of 690 MPa. All bearing plates were
designed to act across the full flange widths of the channels excluding the rounded comer. The length
of bearing (N) was chosen to be the full and half flange width of the channels. The channel specimens
were tested using the four loading conditions according to the AISI Specification. These loading
conditions are EOF, IOF, ETF and ITF as described earlier. Displacement control was used to drive
the hydraulic actuator at a constant speed of 0.8 mm/min. The static load was recorded by pausing for
one minute near the ultimate load. Details of the test set-up and test rig are given in Young and
Hancock (1998).
The experimental ultimate web crippling loads per web
(PExp)
are
given in Tables 2 and 3. Two tests
were repeated for 125x65x4 channel subjected to ITF loading condition, and the test results for the
repeated tests are very close to their first test values, with a maximum difference of 1.5%. The small
difference between the repeated tests demonstrated the reliability of the test results. For 75x40x4
channel (stockier web having
h/t
= 15.3) subjected to EOF loading condition, web crippling was not
observed at ultimate load during testing, but specimens failed in overall twisting of the sections.
t_.
~X
/ri
!-~ bs
Figure 1" Definition of symbols

TABLE 1
NOMINAL AND MEASURED MATERIAL PROPERTIES
Channel
dx bfx t
(mm)
75x40x4
100x50x4
125x65x4
200x75x5
Nominal
0"0. 2 0"0. 2
(MPa)
(MPa)
450
450
450
450
450
440
405
415
Measured
O'u ~'u
(%)
(MPa)
525
545
510
520
20

20
23
24
250x90x6 450 445 530 21
300x90x6 450 435 535 23
Note:lin. =25.4 mm; 1 ksi = 6.89MPa
COMPARISON OF TEST STRENGTHS WITH CURRENT DESIGN STRENGTHS
The web crippling loads per web obtained from the tests are compared with the nominal web crippling
strengths predicted using the AS/NZS 4600 and the AISI Specification for cold-formed steel structures.
Table 2 shows the comparison of the test strengths
(PExp)
with the unfactored design strengths (Pn).
The current design strengths were calculated using the average measured cross-section dimensions and