Investigation of the rotation behaviour of hollow section beams

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EURO PEAN COMMISSION SCIENCE RESEARCH DEVELOPMENT technical steel research Properties and in-service performance Investigation of the rotation behaviour of hollow section beams Report EUR 17994 EN STEEL RESEARCH EUROPEAN COMMISSION Edith CRESSON, Member of the Commission responsible for research, innovation, education, training and youth DG XII/C.2 — RTD actions: Industrial and materials technologies — Materials and steel Contact: Mr H. J.-L. Martin Address: European Commission, rue de la Loi 200 (MO 75 1/10), B-1049 Brussels — Tel. (32-2) 29-53453; fax (32-2) 29-65987 European Commission mmmà si»s rssiirai Properties and in-service performance Investigation of the rotation behaviour of hollow section beams G. Sedlacek, W. Dahl, N. Stranghöner, Β. Kalinowski RWTH-Lehrstuhl für Stahlbau/Institut für Eisenhüttenkunde D-52056 Aachen J. Rondai, Ph. Boeraeve Université de Liège MSM Institut du Génie Civil Quai Banning 6 B-4000 Liège Contract No 7210-SA/119 1 December 1991 to 30 November 1994 Final report Directorate-General Science, Research and Development 1998 EUR 17994 EN LEGAL NOTICE Neither the European Commission nor any person acting on behalf of the Commission is responsible for the use which might be made of the following information. A great deal of additional information on the European Union is available on the Internet. It can be accessed through the Europa server (http://europa.eu.int).

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EURO PEAN
COMMISSION
SCIENCE
RESEARCH
DEVELOPMENT
technical steel research
Properties and in-service performance
Investigation of the
rotation behaviour of
hollow section beams
Report
EUR 17994 EN
STEEL RESEARCH EUROPEAN COMMISSION
Edith CRESSON, Member of the Commission
responsible for research, innovation, education, training and youth
DG XII/C.2 — RTD actions: Industrial and materials technologies —
Materials and steel
Contact: Mr H. J.-L. Martin
Address: European Commission, rue de la Loi 200 (MO 75 1/10),
B-1049 Brussels — Tel. (32-2) 29-53453; fax (32-2) 29-65987 European Commission
mmmà si»s rssiirai
Properties and in-service performance
Investigation of the rotation behaviour
of hollow section beams
G. Sedlacek, W. Dahl, N. Stranghöner, Β. Kalinowski
RWTH-Lehrstuhl für Stahlbau/Institut für Eisenhüttenkunde
D-52056 Aachen
J. Rondai, Ph. Boeraeve
Université de Liège MSM Institut du Génie Civil
Quai Banning 6
B-4000 Liège
Contract No 7210-SA/119
1 December 1991 to 30 November 1994
Final report
Directorate-General
Science, Research and Development
1998 EUR 17994 EN LEGAL NOTICE
Neither the European Commission nor any person acting on behalf of the Commission
is responsible for the use which might be made of the following information.
A great deal of additional information on the European Union is available on the Internet.
It can be accessed through the Europa server (http://europa.eu.int).
Cataloguing data can be found at the end of this publication.
Luxembourg: Office for Official Publications of the European Communities, 1998
ISBN 92-828-4473-0
© European Communities, 1998
Reproduction is authorised provided the source is acknowledged.
Printed in Luxembourg
PRINTED ON WHITE CHLORINE-FREE PAPER Investigation of the rotation behaviour of hollow section beams
Technical Final Report to ECSC
Contents
7
I Objectives
II Summary 7
ΙΠ Conclusions 8
IV Table of Symbols *l
1. Introduction 13
2. Definition of Determining the Rotation Capacity 14
3. Investigations of the Rectangular Hollow Sections5
3.1 Experimental Investigations ^
3.1.1 Test-Setup8
3.1.2 Measurements zu
3.1.2.1s of the Section Geometry and Imperfections 20 2s of the Residual Stresses 2^
3.1.2.3 Measurements during Testing 32
3.1.3 Test Results 33
3.1.4 Stress-Strain-Behaviour6
3.2 Numerical Investigations 4
3.2.1 Finite Element Model
3.2.2l Observations Concerning the Moment-Rotation-Behaviour 4
3.2.3 Investigations Regarding the Influence of the Production Process on the
Moment-Rotation-Behaviour 70
3.2.3.1 Hot-Formed SHS1 2 Cold-Formed SHS
3.2.3.3 Conclusions4
4. Investigations of the Circular Hollow Sections5
4.1 First Test Series
4.1 1 Experimental Investigations
1.1 Test-Setup 76 4.1
1.2 Measurements7 4.1
4.1 1.2.1s of the Section Geometry and Imperfections 7
1.2.2s during Testing9 4.1 4.1.1.3 Test Results 79 4 Stress-Strain-Behaviour 80
4.1.2 Numerical Investigations2
4.1.2.1 Finite Element Model2 Comparison Experimental Results - Numerical Results 8
4.2 Second Test Series 9
4.2.1 Experimental Investigations
4.2.1.1 Test-Setup4 2 Measurements5
4.2.1.2.1s of the Section Geometry and Imperfections 92s during Testing7
4.2.1.3 Test Results 100 4 Stress-Strain-Behaviour1
4.2.2 Numerical Investigations3
4.2.2.1 Finite Element Model2 Comparison Experimental Results - Numerical Results 104
5. Investigations of the Thin Walled Holllow Sections 11
5.1 Rectangular Hollow Sections4
5.1.1 Experimental Investigations
5.1.1.1 Test-Setup 112 Measurements
5.1.1.3 Stress-Strain-Behaviour5 4 Test Results6
5.1.2 Numerical Investigations8
5.1.2.1 Finite Element Model
5.1.2.2 Comparison Experimental Results - Numerical Results π
5.2 Circular Hollow Sections 120
5.2.1 Experimental Investigations
5.2.1.1 Test-Setup2 Measurements
5.2.1.3 Stress-Strain-Behaviour2 4 Test Results
5.2.2 Numerical Investigations5
5.2.2.1 Finite Element Model
5.2.2.2 Comparison Experimental Results - Numerical Results 12
6. Investigations of the Concrete Filled Holllow Sections 127
6.1 Rectangular Hollow Sections
6.1.1 Experimental Investigations127
6.1.1.1 Test-Setup
127 2 Measurements
128
6.1.1.2.1s of the Concrete
129 6.1.1.3 Stress-Strain-Behaviour
129 4 Test Results
JJ 6.2 Circular Hollow Sections
1 jj 6.2.1 Experimental Investigations
l jj
6.2.1.1 Test-Setup
133 2 Measurements
134 6.2.1.2.1 s of the Concrete
134 6.2.1.3 Stress-Strain-Behaviour
135 4 Test Results
139 . References
j
Annex I - RHS 143
Part 1 True Stress-Strain-Curves
Part 2 Locations of Buckles Occured in the Experimental Tests 154
Annex U - CHS 157
Parti True Stress-Strain-Curves
Annex III - Thin Walled Hollow Sections 165
Part 1 True Stress-Strain-Curves 16
Annex IV - Concrete Filled Hollow Sections 167
Part 1 True Stress-Strain-CurvesI Objectives
The research programme shall provide evidence for the moment-rotation characteristics
(moment capacity, rotation capacity) of hollow section beams on the basis of 4-point-bending
tests. Furtheron the present code requirements for plastic and elastic design, which are given
by b/t-ratios, shall also be checked.
The research programme includes 4-point-bending-tests for RHS, CHS and concrete filled
RHS and CHS profiles.
The results of these tests shall be used for the calibration of a computer simulation
programme. The results of the calculations shall be used to identify the influence of the
different parameters on the moment and rotation capacity.
The overall objective of this research project is to check whether the classification of hollow
sections according to the b/t- or d/t-ratios in Eurocode 3 is acceptable or could be improved.
Those ratios tabled in codes are controlled by the yield strength.
The checks should include hollow sections (circular, square and rectangular sections) for
various cross sectional classes without and with concrete infill. Steel grades with yield
stresses up to 460 MN/m2 should be used.
Π Summary
1. The works in the experimental field compose the following tests:
Four-point bending tests have been carried out for cold- and hot-formed square and
rectangular hollow sections made of different steel grades. For circular hollow sections,
which have been investigated as well, two different test-setups have been arranged:
(a) In the first test-setup the beams have been tested in four point bending.
(b) In the secondp the sections have been tested in three- and four-point bending.
2. The numerical simulations show a good agreement with the experimental results when the
following conditions are observed:
Tensile tests to determine the characteristic yield strength should be carried out with coupon
tests taken from a location representative for the 'mean value' of the actual yield strength
distribution for all sections. In the case of hot-formed sections the distribution is almost equal.
In the case of cold-formed sections the 'representative location' has been determined as the
quarter point of a flange and the corner.
Residual stresses have been measured for three section types: one hot-formed section and two
cold-formed sections. It has been shown that they do not have an influence on the rotation
capacity.
Additional comperative tests have been carried out for square and circular thin walled hollow
sections with and without concrete infill. These tests demonstrate that concrete infill reduces
the tendency to local buckling and hence improves the rotation capacity. Failure may occur
by the exceeding of ultimate strain. III Conclusions
1. Rectangular Hollow Sections
1.1 The investigations of the cold-formed square and rectangular hollow sections have shown
that the stress-strain-distribution achieved from tensile tests has an important influence on the
numerical simulations as well as on the definition of the rotation capacities. The locations of
the tensile coupons representative for the characteristic yield strength should be chosen such
that the characteristic yield strength distributions are taken into account. For the determination
of thec yieldh of cold-formed sections, where the influence is significant,
it is proposed to investigate tensile coupons of the quarter points of the flanges and the
corners.
1.2 The rotation behaviour of hot-formed hollow sections is different to the rotation behaviour
of cold-formed sections. Hot-formed class 1 hollow sections (according to Eurocode 3)
behave like class 2 sections, i.e. they do not exceed the plastic moment, they only reach it.
Therefore, they do not exhibit rotation capacity by definition. However, cold-formed class
1 sections exceed their plastic moments and therefore by definition rotation capacities are
achieved.
1.3 The numerical simulations corresponded in general with the experimental results. In
comparison with the results of finite element simulations, somel results, achieved
for the hot-formed sections, lead to too high rotation capacities, when based on the 0.95 Mpl-
level, because in the decreasing slope of these sections the moment resistance does not
decrease in the 'typical' way.
1.4 Two dependences can be seen from the simulations as well as from the experiments for
the cold-formed square hollow sections:
The smaller the yield strengths in the flanges are, the higher are the rotation
capacities.
The smaller the momentgradient is, the smaller is the rotation capacity.
The last conclusion is also valid for the hot-formed square hollow sections.
1.5 Cold-Formed square hollow sections seem to have higher moment resistance, they achieve
rotation capacities by definition and are therefore useable for plastic design. Hot-formed
square hollow sections do not achieve rotation capacities on the Μ,,,-level. Therefore, they
only seem to be useable for plastic design when the existing definition of the rotation
capacitiy is amended and rotation capacity can be given also for other levels rather than Mpl.
2. Circular Hollow Sections
2.1 In both test-setups the achieved rotation capacities for the circular hollow sections are
higher than those for the square hollow sections. Therefore, it seems that hot-formed circular