core, structure, designfindings of the diaphragm action tests • the shear diaphragm action depends...
TRANSCRIPT
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Prof. Dr.-Ing. Jörg Lange
Institut für Stahlbau und Werkstoffmechanik, TU Darmstadt, Germany
Core, Structure, Design
Research with Sandwich Panels
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Core Made of Corrugated Cardboard
picture: A. von der Heyden
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• Problems of common core materials:
• Petroleum-based
• Production is energy consumptive
• Recycling difficult and expensive
• Disposal pollutes the environment
Ecological core material for sandwich panels
has to be found…Corrugated Cardboard?
Introduction
Source: polyurethan.isopol.de
Source: cafol.my-icg.de
Source: commons.wikimedia.orgSource: www.ybj-print.com
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Experimental Assessment
• Cardboard is considered to be orthotropic
• Orthotropy due to geometry of corrugations and
due to fibre orientation in paper
• Tests conducted:
• Compression tests
• Tensile test
• Shear tests
• Bending tests
on sandwich beams
• Thermal conductivity
• Controlled climate 20°C, 65 % RH
in different
directions
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Summary
• Corrugated cardboard with regard to bearing properties suitable for
sandwich panels in building industry
• Corrugated cardboard has many advantages in respect of
ecological issues compared to common core materials
Corrugatedcardboard
Polyurethane foam Mineral wool
Density in kg/m³ 100 to 140 35 to 45 90 to 150
Young‘s modulusin N/mm²
3 to 450 2 to 6 3 to 15
Shear modulusin N/mm²
5 to 200 2 to 5 3 to 15
Compressive strengthin N/mm²
0.08 to 1,4 0.1 to 0.15 0.05 to 0.15
Thermal conductivity in W/(m·K)
0.04 to 0.09 0.02 to 0.03 0.03 to 0.05
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Diaphragm Action of Sandwich Panels
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Diaphragm Action of Sandwich PanelsExperimental Assessment
picture: Ch. Kunkel
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Experimental AssessmentExperimental Set-Up for the Diaphragm Action Tests
A
HEB 140
HEB 260
View A
Sandwich Panel
Square tube 40x40
(4 mm)
2,86 m
HEB 260
HEB 260
HE
B 1
40
4,0
5 m
F
HE
B 1
40
C
D
AB
picture: Ch. Kunkel
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Experimental AssessmentResults of the Diaphragm Action Tests
0
2
4
6
8
10
12
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18
20
0 5 10 15 20 25 30 35
Load
in k
N
Displacement of the rig in mm
Diaphragm action (Wall panels dc = 100 mm - 4 x 2,86 m)
Wall panel 100 mmType I - Test 1
Wall panel 100 mmType I - Test 2
Wall panel 100 mm -Hook-and-Loop-Tape -Type I - Test 1
Wall panel 100 mm -Hook-and-Loop-Tape -Type I - Test 2
0
2
4
6
8
10
12
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16
18
20
0 5 10 15 20 25 30 35
Load
in k
N
Displacement of the rig in mm
Diaphragm action (Wall panels dc = 100 mm - 4 x 2,86 m)
Wall panel 100 mmType I - Test 1
Wall panel 100 mmType I - Test 2
hook-and-
loop-tape}
picture: Ch. Kunkel
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Experimental AssessmentFindings of the Diaphragm Action Tests
• The shear diaphragm action depends on the stiffness of the
connection between panels and substructure.
• The assembly of the fastenings is accountable for the maximum
bearing capacity.
• The connections of the panels via the longitudinal joint
participate in the shear diaphragm action.
How does the longitudinal joint transfer
the load between the panels?
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Experimental AssessmentExperimental Set-Up for the Longitudinal Joint Tests
Load steps of the
horizontal force:
0,5 kN
1,0 kN
1,5 kN
2,0 kN
picture: Ch. Kunkel
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Experimental AssessmentResults of the Longitudinal Joint Tests
Longitudinal joint with standard sealing tape
Sealing tape
picture: Ch. Kunkel
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Experimental AssessmentStrengthening of the Longitudinal Joint
Hook-and-loop-tape (glued with one component polyurethane prepolymer adhesive)
picture: Ch. Kunkel
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Experimental AssessmentResults of the Longitudinal Joint Tests
Longitudinal joint with hook-and-loop-tape
Hook-and-loop-tape
instead of sealing tape
picture: Ch. Kunkel
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• Longitudinal joints effect the bearing capacity of the diaphragm action
→ Integration of the joint in the calculation model
• Improvement by strengthening the joint by hook-and-loop-tape
→ Maximum load up to twice as high
Summary
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ETA
pull-out
pull-over
shear
V
N
Interaction
picture: K. Kilian
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Interaction - Tests
picture: K. Kilian
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Bearing capacity of the sandwich panel
if VE,d
VR,I,d≤ 0,25
NE,d
NR,I,d≤ 1,0
only if VEd is cyclic or deflections are restricted (3 mm)
0,25 <VE,d
VR,I,d≤ 1,00
NE,d
NR,I,d+
VE,d
VR,I,d≤ 1,0
NR,I,d Design value for pull-over
VR,I,d Design value for shear
Bearing capacity of supporting structure
according to
• for steel: EN 1993-1-3:2006
• for aluminum: EN 1999-1-4:2007
• for timber: EN 1995-1-1:2004+A1:2008
NR,II,d Design value of pull-out
VR,II,d Design value for shear
N
Interaction – Recommendation (Bracing)
V
picture: K. Kilian
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Curved Panels
picture: St. Schäfer
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Curved Panels
picture: St. Schäfer
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Curved Panels
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Curved Panels
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Prof. Dr.-Ing. Jörg Lange
Institut für Stahlbau und Werkstoffmechanik, TU Darmstadt, Germany
Core, Structure, Design
Research with Sandwich Panels