Strength of the compressed thin

Saint-Petersburg State Polytechnical University
HAMK University of Applied Sciences
Report at
«International Scientific Conference and Workshop «METNET»
«Strength of the compressed thin-walled studs: tests and FEM-modelling»
Contributors:
Nikolay I. Vatin , Alexey S. Sinelnikov
Jarmo Havula, Lassi Martikainen
Saint-Petersburg, Hämeenlinna
2014
Abstract
This summary report is based on the experimental and numerical research of thinwalled cross-section’s compression resistance carried out in St. Petersburg State
Polytechnical University and HAMK University of Applied Sciences, Sheet Metal
Centre. Current situation on the Russian market concerning the usage of cold-formed
thin-walled cross-sections is aimed to find out a base foundation to start up a stipulation
of the elements under discussion in the building industry. Some questions about the
compression resistance of such cross-sections were raised on different conferences by
scientific community and by companies such as Rautaruukki Oyj (Finland). Steel
galvanized C- and U-profiles and thermo-profiles are types of thin-walled cross-sections
are normally used in small houses construction. Thermo-profiles have slots in webs that
decrease the thermal flow through the web, but have a negative effect on strength of
the profiles. These profiles were object of the research. Investigations carried out
included tests to prove the compression resistance of the single thin-walled studs and
stud-to-rack joints. Numerical modeling of thin-walled cross-sections was done with
contemporary analysis software (SCAD Office) using the finite element method
(FEM).
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Researches
Studies undertaken by the authors in recent years have revealed that today‘s
building market in Russia is looking for building materials and technologies that could
provide low-height housing industry with high-speed of construction, safety, ecological
compatibility and finance efficiency.
The lightweight thin-walled cold-formed steel structures allow getting advantages
that meet the requirements described above. Due to some reasons we, in Russia, do
not have current norms that could be applied by engineers who design houses using
the cold-formed steel structures. In this area a number of Doctoral theses have been
defended during recent years in Russia (G.I. Belyy, A.R.Tusnin, I.V. Astahov, A.U.
Kuznetsov). Theoretical research and laboratory tests were done only for specific
types of thin-walled cross-sections.
Jyrki Kesti contributed a good deal to the development of local and distortional
buckling of perforated steel wall studs (Espoo, 2000). Today thin-walled cold-formed
steel structures won a good place in the Finnish building area. Experience that Finnish
engineers have could help Russian science community to understand more exactly
behavior of such a structures and appropriate European norms.
Summary of the research described below concerns reticular-stretched thermoprofiles. Reticular-stretched thermo-profile is a new type of thin-walled cross-sections
that found its place in Russian market.
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General
As an object of research reticular-stretched thermo-profiles and their joints were
analyzed (see figure 1). The following profiles are discussed:
1. Specimen S1 (stud) - АИ ТCс 200-45-2,0;
2. Specimen S2 (rack) - АИ ПН 200-50-2,0.
Steel used for specimen production has the following parameters:
1. Steel grade - 350 (yield strength not less than 350 H/mm2);
2. Coating mass, 350g/m2;
3. Coating thickness, 25 microns.
The research goal was to form
the theoretical rationale for usage of
reticular-stretched
thermo-profile
throughout buckling analysis based
on the laboratory tests.
Fig. 1 Reticular-stretched thermo-profiles
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Research tasks
Research tasks:
1. Laboratory tests:
− Compression test: single studs and stud-to-rack joints.
2. Numerical modeling (FEM):
− Buckling analysis.
3. Comparison of results.
Fig. 2 Compression test. Single stud and Stud-to-rack joint
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Experimental investigations
Compression test
1. Test specimen:
• C–shaped thermo-slotted profiles АИ ТCс 200-45-2.0;
• Web height - 200mm, flange width - 45mm, single edge fold stiffener – 15mm,
steel thickness - 2,0mm;
• Total lengths of the specimen 350 and 1000 mm;
• Support blocks (thickness 40 mm; edge is positioned 3 mm from the end of the
profile) made of wood are placed inside the profile at the ends;
• 7 specimen (4 single studs and 3 stud-to-rack joints).
2. Test arrangement:
• The lower end of the specimen is placed on a hinged support made of steel or
on a floor;
• The load of a hydraulic cylinder is applied to the special hinged element through
a thick steel plate to the upper end of the specimen;
• Point of load application is 10mm from the outside surface of the web.
3. Test procedure:
• The specimen is loaded using the displacement control until the failure of the
specimen;
• The loading rate is different (1.0; 1.33; 2.0; 3.0; 4.0 mm/min).
4. Test results:
• Buckling form and force.
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Experimental investigations
Test results. Photos
Fig.3 Compression test
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Experimental investigations
Test results. Photos
Fig.4 Compression test
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Experimental investigations
Test results. Photos
Fig.5 Stud-to-rack joint. Specimen C1…C3
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Experimental investigations
Test results. Compression test diagram (S3)
Fig. 6 Compression test diagram (S3)
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Experimental investigations
Test results. Compression test diagram (S1,S2,S4)
Fig. 7 Compression test diagrams (S1,S2,S4)
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Experimental investigations
Test results. Compression test diagram (C1,C2,C3)
Fig. 8 Compression test diagrams (C1,C2,C3)
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Experimental investigations
Test results
Table 1. Test results
Type of profile/ Specimen number
Compression test
Buckling force, kN
АИ ТCс 200-45-2,0 (S1)
АИ ТCс 200-45-2,0 (S2)
АИ ТCс 200-45-2,0 (S3)
АИ ТCс 200-45-2,0 (S4)
АИ ТCс 200-45-2,0 (C1)
АИ ТCс 200-45-2,0 (C2)
АИ ТCс 200-45-2,0 (C3)
84.35
68.89
53.82
83.36
90.82
92.99
99.88
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Reticular-stretched VS. Usual web-slotted profile
Fig. 9 Reticular-stretched and usual web-slotted profiles
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Reticular-stretched VS. Usual web-slotted profile
Test results
Table 2. Test results (mean values)
Type of profile
АИ ТCс 200-45-2,0
АИ ТC 200-45-2,0
Compression test
Difference
Buckling force, kN
%
78.19
39.98
96
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Numerical modeling (FEM)
Numerical modeling of thin-walled cross-sections and their stud-to-rack joint was
done with contemporary analysis software (SCAD Office) using finite element method
(FEM). FEM-models’ parameters were the same as for the tests described above.
During the modeling process the thin-walled profile based on shell-elements (see figure
10).
Characteristic of shell-element models:
• Finite element dimensions – 3 mm;
• Absolute solid body;
• Hinged and combined boundary
conditions.
Fig. 10 FEM-model of reticular-stretched profile (shell-elements)
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Comparison test and FEM-modeling results
Table 3. Test and FEM analysis results
Type of profile
Compression test
350mm
1000mm
Buckling analysis
Shell
%
Buckling force, kN
АИ ТCс 200-45-2,0
АИ ТCс 200-45-2,0
93.7
53.82
-
Difference
53.5
85.9
0.6
8.3
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Numerical analysis (FEM)
Numerical modeling of reticular-stretched profile studs with length 1000, 2000 and
3000mm were done.
Types of the cross-sections (see figure 11):
• АИ ТCс 150-45-1.5 (2.0);
• АИ ТCс 175-45-1.5 (2.0);
• АИ ТCс 200-45-1.5 (2.0);
• АИ ТCс 250-45-1.5 (2.0).
Characteristic of shell-element models:
• Finite element dimensions – 3 mm;
• Absolute solid body;
• Hinged boundary conditions.
Accidental eccentricity (SNiP II-23-81*):
Fig. 11 FEM-model of reticular-stretched profile (shell-elements)
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Numerical analysis (FEM).Results
Table 4. FEM analysis results: critical load and buckling form
№
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Type of profile
Radius of
gyration
ТСс 150-45-1.5
16,41
ТСс 150-45-2.0
16,19
ТСс 175-45-1.5
16,04
ТСс 175-45-2.0
15,82
ТСс 200-45-1.5
15,65
ТСс 200-45-2.0
15,44
ТСс 250-45-1.5
14,90
ТСс 250-45-2.0
14,69
Length, m
1000
2000
3000
1000
2000
3000
1000
2000
3000
1000
2000
3000
1000
2000
3000
1000
2000
3000
1000
2000
3000
1000
2000
3000
Axial compression
Eccentrical compression
Eccentricity
Slenderness
, mm
Critical load, kN Buckling form Critical load, kN Buckling form
4,28
5,61
6,95
4,27
5,60
6,94
4,71
6,05
7,38
4,70
6,04
7,37
5,14
6,47
7,80
5,13
6,46
7,79
5,96
7,29
8,62
5,95
7,28
8,61
61
122
183
62
124
185
62
125
187
63
126
190
64
128
192
65
130
194
67
134
201
68
136
204
44,6
42,9
30,2
83,9
78,4
41,6
36,6
34,2
29,0
69,6
65,8
40,8
29,2
27,2
26,2
55,8
53,1
39,7
19,8
18,3
17,9
38,2
36,9
35,9
Local
Local
Overall
Local
Overall
Overall
Local
Local
Overall
Local
Local
Overall
Local
Local
Local
Local
Local
Overall
Local
Local
Local
Local
Local
Overall
37,7
36,2
26,6
71,3
69,0
36,9
31,4
29,1
25,1
60,2
56,0
35,6
24,8
22,8
21,2
47,7
44,3
34,1
16,4
14,7
13,9
31,8
29,8
28,1
Local
Local
Overall
Local
Local
Overall
Local
Local
Overall
Local
Local
Overall
Local
Local
Local
Local
Local
Overall
Local
Local
Local
Local
Local
Local
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Conclusions
1. New type of thin-walled thermo-profile (reticular-stretched) were analyzed.
2. Laboratory tests of the reticular-stretched profile under compression showed that
local buckling appears before overall buckling for the profiles with small slenderness
(λmax = 60…70). It was experimentally proved flexural and torsion-flexural buckling
forms.
3. Comparative analysis of experimental data for reticular-stretched profile and usual
web-slotted profile showed that bearing capacity of the first one is more than the last
one by about 95%. Middle positioned stiffener with grooved form is good design
solution.
4. Numerical analysis (FEM) of the reticular-stretched profiles with parameters that
are the same as for the tested specimens showed good results with normalized
difference not more than 8%.
5. Numerical analysis (FEM) of the reticular-stretched profiles with different web
height (150, 175, 200 and 250mm) and steel thickness (1.5 and 2.0mm) showed that
dominant type of buckling form depends on slenderness of the cross-section.
6. Summary of the investigations should be taken as a step to apply finite element
method for modeling profile behavior without real tests.
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Acknowledgements
The experimental work was commented by Arto Ranta-Eskola, director of research,
Rautaruukki Oyj (Finland).
The authors also gratefully acknowledge the helpful comments and suggestions of
the reviewers, which have improved the presentation.
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References
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
Astakhov, I. V. Prostranstvennaia ustoichivost' elementov konstruktsii iz kholodnognutykh profilei,
Dissertation, St.-Petersburg, 2006, 123 p.
Belyi, G. I. Raschet uprugoplasticheskikh tonkostennykh sterzhnei poprostranstvenno-deformiruemoi
scheme, Stroitel'naia mekhanika sooruzhenii: Mezhvuz. temat. sb. tr, LISI. №42, 1983, pp. 40-48.
EN 1993-1-3, Design of Steel Structures: Cold-formed thin gauge members and sheeting.
Gordeeva, A. O. and Vatin, N. I. Magazine of Civil Engineering, №3(21), 2011, pp. 36-46.
Hartmut Pasternak and John Ermopoulos. Design of steel frames with slender joint-panels, Journal of
Constructional Steel Research, Vol.35, Issue 2, 1995, pp. 165-187.
Kesti, J. Local and distortional buckling of perforated steel wall studs, Dissertation for the degree of
Doctor of Science in Technology, Espoo, 2000, 101p. + app.19p.
Kriksunov, E.Z., Perel'muter, A.V. and Urchenko ,V.V. Proektirovanie flantsevykh soedinenii ramnykh
uzlov, Promyshlennoe i grazhdanskoe stroitel'stvo, №2, 2010, pp. 33-37.
Rasmussen, K. J. R. Journal of Constructional Steel Research,Vol.65,Issues 8-9,2009,pp.1677-1684.
Schafer, W. and Pekoz, T. Computational modeling of cold-formed steel: characterizing geometric
imperfections and residual stresses, Journal of Constructional Steel Research, Vol.47,1998, pp.193-210.
Shatov, D. S. Magazine of Civil Engineering, №3(21), 2011, pp. 32-35.
Smaznov D.N. Konechno-elementnoe modelirovanie stoek zamknutogo secheniia iz kholodnognutykh
profilei
,
Nauchno-tekhnicheskie
vedomosti
Sankt-Peterburgskogo
gosudarstvennogo
politekhnicheskogo universiteta, №123, 2011, pp. 334-337.
SP 16.13330.2011, Steel structure, М. Minregion razvitiya RF, 2011, 171 p.
Tusnin, A. R. Chislennyi raschet konstruktsii iz tonkostennykh sterzhnei otkrytogo profilia, Moscow: Izdvo ASV, 2009, 143 p.
Vatin, N.I. and Sinelnikov ,A.S. Strength and Durability of Thin-Walled Cross-Sections, Design,
Fabrication and Economy of Metal Structures. International Conference Proceedings, 2013, Miskolc,
Hungary, April 24-26, Miskolc, 2013, pp. 165-170.
Winter, George. Light Gauge (Thin-Walled) Steel Structures for Building in the U.S.A. preliminary
publication, 4th Congress of the International Association for Bridge and Engineering, 1952, 524 p.
Zhmarin E.N. Internet Journal "Construction of Unique Buildings and Structures", №2, 2012, pp. 27-30.
22 of 23
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