Stability behaviour of non- conventional cold-formed steel ... · cold-formed steel structures ESMC...
Transcript of Stability behaviour of non- conventional cold-formed steel ... · cold-formed steel structures ESMC...
Department of Structural EngineeringBudapest University of Technology and Economics
Stability behaviour of non -conventional
cold -formed steel structures
ESMC 2009 September 7-11, 2009, Lisbon
László Dunai Gábor Jakab
Professor Asst. Professor
Budapest University of Technology and Economics
Department of Structural Engineering
Department of Structural EngineeringBudapest University of Technology and Economics
„Non -conventional”
Cold-formed sections fabrication; new generation of products
Novel structural functions in buildings
New structural arrangements
ESMC 2009 September 7-11, 2009, Lisbon
New structural arrangements
Design rules ?
Experimental research and development
DESIGN
Department of Structural EngineeringBudapest University of Technology and Economics
Section types combined sections
Eccentricities eccentric section arrangements in joints
eccentric load introduction on section elements
Non-conventional arrangements
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Connections connectors, contacts
Lateral supports discrete position; partial rigidity
Department of Structural EngineeringBudapest University of Technology and Economics
section section
connection structural
element
Interaction
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element
structural element joint
Stability behaviour ?
Department of Structural EngineeringBudapest University of Technology and Economics
Frame
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Frame – application
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Department of Structural EngineeringBudapest University of Technology and Economics
Truss
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Department of Structural EngineeringBudapest University of Technology and Economics
Truss – application
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Department of Structural EngineeringBudapest University of Technology and Economics
FE model
EXPE
DE
Pilot test
Verification test
FE simulation
Research methodology
Analysis
Virtual
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ERI
MENT
ESIGN
Validation test
Design test
Prototype test
Design method
Struct. details
Design value
Virtual experiment
Department of Structural EngineeringBudapest University of Technology and Economics
Structural element and connection
Structural joint
Research strategy
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Structural joint
Global structure
Department of Structural EngineeringBudapest University of Technology and Economics
Structural element and connection C-section, screw connection
Research strategy
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Structural joint
Global structure truss
Department of Structural EngineeringBudapest University of Technology and Economics
Fundamental research on element behaviour
Subject of the research– centric/eccentric compression– combined built-up sections– load introduction– lateral restraints
C-section structural elements
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– lateral restraints
Aims– stability behaviour– failure mode identification– FE model development, verification, application– design method development, validation
Department of Structural EngineeringBudapest University of Technology and Economics
Experimental program
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• 10 different section and end connection arrangements• 98 tests• C150/1.0 – C200/2.5
– web b/t: 80-200• Specimen lengths
– 800, 1500, 2000, 2500, 3600 mm
Department of Structural EngineeringBudapest University of Technology and Economics
Test preliminary design
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Department of Structural EngineeringBudapest University of Technology and Economics
Single C -section elements
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Department of Structural EngineeringBudapest University of Technology and Economics
Element end failure
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Short screw layouton web
Stub column –web connection
Load introduction at the whole section end
Department of Structural EngineeringBudapest University of Technology and Economics
Screw arrangement – web/flange
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Department of Structural EngineeringBudapest University of Technology and Economics
Screw arrangement – web
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Department of Structural EngineeringBudapest University of Technology and Economics
„I-section” elements
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Department of Structural EngineeringBudapest University of Technology and Economics
Single double section
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Department of Structural EngineeringBudapest University of Technology and Economics
„Hollow” section elements
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Tension and compression side C or U loaded
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Behaviour modes
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Laterally supported elements
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Department of Structural EngineeringBudapest University of Technology and Economics
Software : ANSYS
Element : SHELL181 (4-node, 24 DOF’s)
Material model : linear elastic – hardening
plastic
Single C -section element FE model
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plastic
Contact surfaces : CONTA173/TARGE170
Self-drilling screw model :
– „beamstar”; BEAM4
– calibrated stiffness parameters
Model size : ~ 100000 DOF’s (L=2500 mm)
Contact surfaces
Shank elementRadial elements
Department of Structural EngineeringBudapest University of Technology and Economics
cFSM analysis pure modes FE model
Geometrical imperfections
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20
40
60
80
100
120
FE
res
ista
nces
[kN
]
FE analysis
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00 20 40 60 80 100 120
Test resistances [kN]
Department of Structural EngineeringBudapest University of Technology and Economics
EC3-1-3:1996y = 0.975x
R2 = 0.98
EC3-1-3:2006y = 0.9777x
R2 = 0.9596
Rt = Rd
100
120
140
160
180
200
Des
ign
resi
stan
ces
(Rd)
[kN
]Single section element resistances
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0
20
40
60
80
100
0 20 40 60 80 100 120 140 160 180 200
Test resistances (R t) [kN]
Des
ign
resi
stan
ces
(R
1996 2006 Rt = Rd EC3-1-3:1996 trend EC3-1-3:2006 trend
Department of Structural EngineeringBudapest University of Technology and Economics
1
8.0
,
8.0
,
≤
∆++
Rdb
EdEd
Rdb
Ed
M
MM
N
N
1/
)(
/ 0,,
,,
0min
≤⋅
∆+⋅+
⋅⋅ Mcomzeffyb
EdzEdzz
Meffyb
Ed
Wf
MM
Af
N
γκ
γχ nomEdEdz eNM ⋅=,
nomee ⋅= 4.1mod
Sye ⋅≥ 4.0mod
EC3-1-3:1996
EC3-1-3:2006
Buckling – bending design resistance
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( ) ( ) 165.065.0
,,≤+ ∆+
Rdb
EdEd
Rdb
Ed
MMM
NN
Sye ⋅≥ 4.0mod
Department of Structural EngineeringBudapest University of Technology and Economics
αγ
κγχ
≤⋅
∆+⋅+
⋅⋅ 1,,
,,
1min /
)(
/ Mcomzeffyb
EdzEdzz
Meffyb
Ed
Wf
MM
Af
N
Section type α
Double section design resistance
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I column 0.8·L+1.0, L – element length [m]
CC 1.8
CU1.3 – C-section loaded1.8 – U-section loaded
I brace 2.5
Department of Structural EngineeringBudapest University of Technology and Economics
Subject of the research– full-scale truss experimental study– different structural elements– different joints
Aims
C-section truss
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Aims– interacting stability behaviour– failure mode identification– FE model development, verification– design method validation
Department of Structural EngineeringBudapest University of Technology and Economics
failure in the upper
Test #1
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failure in the upper chord, interaction
of bending and flexural buckling
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failure in the lower chord
Test #5/1
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failure in the lower chord
joint nearest to the supportinteraction of shear and
tension
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failure of the upper chord; interaction of bending and
Test #5/2
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interaction of bending and flexural buckling
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30
40
50Lo
ad [k
N/ja
ck]
Load -deflection relationship
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0
10
20
0 20 40 60 80 100Deflection [mm]
Load
[kN
/jack
]
Test No. 1 Test No. 2 Test No. 3 Test No. 4 Test No. 5
Department of Structural EngineeringBudapest University of Technology and Economics
Truss FE model
Software : ANSYS
Element : SHELL181 (4-node, 24 DOF’s)
Material model : linear elastic –
hardening plastic
Contact surfaces :
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Contact surfaces :
CONTA173/TARGE170
Bolt model :
– modified „beamstar”; BEAM4
– calibrated stiffness parameter
Imperfections : selected eigenmodes
Model size : ~ 1.400.000 DOF’s
Shank element
Rigid radial link
Radial beam element
Department of Structural EngineeringBudapest University of Technology and Economics
Eigenmodes – imperfections
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FE analysis – joint failure1 2
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12
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FE analysis – chord buckling
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Department of Structural EngineeringBudapest University of Technology and Economics
1/
)5.0(
/
)(
/ 1,,
,,
1,,
,,
1min
≤⋅
∆+⋅⋅+
⋅⋅∆+⋅
+⋅⋅ Mcomzeffyb
EdzEdzz
McomyeffybLT
EdyEdyLT
Meffyb
Ed
Wf
MM
Wf
MM
Af
N
γκ
γχκ
γχ
Compression chord: single section resistance --- reduced out-of-plane eccentricity
Brace: single and I-section resistance
Design method
N-joint : shear resistance and interaction of joint and chord member
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N-joint : shear resistance and interaction of joint and chord member
5
,,
3 M
effvywRdb
AfV
γχ
⋅⋅⋅
=
( ) ( ) 52
,,,,0,0 //1 MRdbEdyeffvyeffveffRd VVfAfAAN γ
−⋅⋅+⋅−=
Department of Structural EngineeringBudapest University of Technology and Economics
Research methodology: from experiments to design of non-
conventional cold-formed steel structures.
Experiments on C-section elements: test results for a wide range of
arrangement (section, load introduction); modified stability behaviour
modes.
Concluding remarks
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FE model for screwed members: screw model, cFSM pure mode
imperfections, calibration, test domain extension.
Development of cold-formed structures: truss, frame, purlin,
composite floor beam; experimental and numerical research.
Global advanced FE model: development, verification, applicability.
Design methods: experimental and numerical validation of modified
and/or new application rules for the structural elements, joints and
structure.
Department of Structural EngineeringBudapest University of Technology and Economics
ESMC 2009 September 7-11, 2009, Lisbon
Thank you for your attention!