behaviour of a cold-formed steel portal frame in fire: full scale testing
TRANSCRIPT
Behaviour of a cold-formed steel
portal frame in fire: full scale
testing and finite element analysis
Ross Johnston
Project Advisors:
Dr. M. Sonebi
Dr. J.B.P Lim
Prof. C.G. Armstrong
Centre for Built Environment Research
START: Simple Problem
Determine the collapse behaviour of cold-formed steel portal frame structures at elevated temperatures (fire). Provide guidance to prevent undesirable outwards collapse mechanism.
Image courtesy of BBC, http://www.bbc.co.uk/news/uk-england-london-19234182. Accessed 13/08/2012,
START: Simple Problem
FINISH: Simple Solution
Funding
Literature Review
Constraints
Time
Collaboration
Current Practice
Benchmarking
Ambient validation prior to fire
Coupled instabilities
Lab testing
C
O
M
P
L
E
X
Image courtesy of CSB.
What is a cold-formed steel portal frame?
Viable alternative Sustainable Popular in Australia/NZ
Joints possess reduced capacity Limited research + guidance
Image courtesy of SCI P313 Publication, Simms and Newman.
Current guidance Only available for hot rolled steel portal frames. Based on SCI P313 Guidance
Document. No such guidance for cold-formed steel portal frames.
WHERE TO START?
DEVELOP RESEARCH AT AMBIENT TEMPERATURE FIRST
Funding
Literature Review
Constraints
Time
Collaboration
Current Practice
Benchmarking
Ambient validation prior to fire
Coupled instabilities
Lab testing
Ambient temperature (i)
OUTPUT:- BOLT STIFFNESS
0
5
10
15
20
25
30
35
40
0 1 2 3 4 5 6 7 8 9
Load
(k
N)
Displacement (mm)
LAB test avg
ABAQUS FE
Zad./ Bryan
Ambient temperature (ii)
OUTPUT:- JOINT RIGIDITY
Ambient temperature (iii)
0
5
10
15
20
25
0 20 40 60 80 100
Load
(kN
)
Apex Displacement (mm)
OUTPUT:- VALIDATED AT AMBIENT TEMP
Elevated Temperature Study
Funding
Literature Review
Constraints
Time
Collaboration
Current Practice
Benchmarking
Ambient validation prior to fire
Coupled instabilities
Lab testing
CARRY OUT FULL SCALE SITE TEST AND VALIDATE NUMERICAL MODELS
Site test – planning
Site test – planning
Site test – construction
Site test – loading & instrumentation (i)
Site test – setup
Site test – images of building on fire
Site Fire Test Video
Site Test Results - temperature
Site Test Results – lateral eaves displacement
Site Test Results – frame displacement
Site Test Results – finite element
Firstly…What
happens to
steel in fire?
STRESS STRAIN CURVES
YOUNG’S MODULUS
EXPANSION
CONNECTION STIFFNESS
CONDUCTIVITY
SPECIFIC HEAT
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 200 400 600 800
Stif
fne
ss (
kN/m
m)
Temperature
Site Test Results – finite element
Site Test Results – finite element validation
-300
-200
-100
0
100
200
300
400
500
600
700
800
900
1000
1100
0 100 200 300 400 500 600 700 800 900 1000
La
tera
l E
av
es D
isp
lace
men
t (m
m)
Temperature (°C)
EXP Column H EXP Column B FE Column H FE Column B
Variance in FE and EXP due to beneficial effect of purlins, side-rails and
cladding?
Single portal frame model not able to accurately model this, need a multi-bay
portal frame arrangement.
Site Test Results – finite element
Parametric Study
-150
-130
-110
-90
-70
-50
-30
-10
10
30
50
0 100 200 300 400 500 600 700 800
Ve
rtic
al A
pe
x D
isp
lace
me
nt
(mm
)
Temperature (°C)
Shell Idealisation (nlgeom)
Beam Idealisation (nlgeom)
Potential for Application of Results
• Practical design guidance for engineers • Base for further research into the behaviour of such structures at elevated temperatures. •Design Procedure
•Critical Temperature
•Influence of purlins/side rails
•Effect of fire scenario
•Base fixity and Overturning moment
Acknowledgements Funding body Department for Employment and Learning (DEL). (For funding of full-scale site fire test: IStructE, ICE and EcoSteel Sdn. Bhd.) Acknowledgements My project advisors, Dr. M. Sonebi, Dr. J. Lim and Prof. C.G. Armstrong. Thanks to Mr Mei of EcoSteel Sdn. Bhd., Dr. H.H. Lau of Curtin University, Sarawak, Malaysia and Dr. Y. Xu, Strathclyde University for their expertise and continued collaboration within this research area. Dr. G. Abdelal, Dr. A. Hu and Mr A. Wrzesien for their assistance in composition of models. Further details Ross Johnston (E: [email protected]) Dr M Sonebi (E: [email protected]) Dr J Lim (E: [email protected]) Prof C. G. Armstrong (E: [email protected])
Site test – planning (iii) Thank you for your
attention