Analytical Investigation of the Thermal Performance of ...
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Structural and Thermal Performance of Precast Concrete Sandwich Wall Panels Stephen Pessiki Professor and Chairperson Department of Civil and Environmental Engineering Lehigh University Bethlehem, PA USA [email protected]
Transcript of Analytical Investigation of the Thermal Performance of ...
Structural and Thermal Performance of
Precast Concrete Sandwich Wall Panels
Stephen Pessiki
Professor and Chairperson
Department of Civil and Environmental Engineering
Lehigh University
Bethlehem, PA USA
Sponsors
• Precast/Prestressed Concrete Institute
• Pennsylvania Infrastructure Technology
Alliance
• Lehigh University
• Composite Technologies Corporation
• Dayton Superior Corporation
• H. Wilden and Associates
• High Concrete Structures Inc.
• Metromont Prestress Company
• Morse Bros. Inc.
• Nitterhouse Concrete Products
• Owens Corning
• Stresscon Corporation
• Tindall Concrete
High Concrete Structures, Inc.
High Concrete Structures, Inc.
“Sandwich” Wall Panel
3-2-3
( 75-50-75 mm )
2.5 ft
2.5 ft
40 ft
3-2-3
1.0 ft
12 ft 12 ft
3-2-3
Typical Two-wythe Sandwich Wall Panels1.0 ft
12 ft
3-2-3
Panel Fabrication
High Concrete Structures Inc.
High Concrete Structures Inc.
Panel Fabrication
High Concrete Structures Inc.
Panel Fabrication
High Concrete Structures Inc.
Panel Fabrication
High Concrete Structures Inc.
Panel Fabrication
Problem 1:
Designers made different
assumptions for flexure design:
• Non-composite panel
• Composite panel
• Partially composite panel
Composite action depends upon
shear transfer mechanisms between
concrete wythes
• Solid concrete regions
• Mechanical connectors
• Bond
High Concrete Structures Inc.
Common mechanical connector –
M-tie
Areas of solid concrete through
the entire panel thickness
are “thermal bridges”
Problem 2:
Thermal Performance of 2-
wythe panels
Objectives
1. Investigate flexural behavior with a
focus on composite action
2. Investigate thermal performance
with a focus on thermal bridges
Test Matrix – Flexural Tests
Panel M-tie Bond Solid
Concrete Primary Variable
1 Prototype panel
2 M-tie connector
3 Solid concrete
4 Bond
Test Specimen 1 - Prototype Panel
2’-0”
4’-6” 6’-0” 16’-0” 6’-0” 4’-6”
37’-0”
6’-0”
8”
1’-0”
3-2-3
Test Specimen 2 - M-tie Panel
4’-6” 6’-0” 16’-0” 6’-0” 4’-6”
37’-0”
6’-0”
8”
2’-0”
3-2-3bond breaker
removable lifting insert
Test Specimen 3 - Concrete Panel
4’-6” 6’-0” 16’-0” 6’-0” 4’-6”
37’-0”
6’-0”
8”
1’-0”
3-2-3bond breaker
Test Specimen 4 - Bond Panel
4’-6” 6’-0” 16’-0” 6’-0” 4’-6”
37’-0”
6’-0”
8”
3-2-3
removable lifting insert
Test Set-up
Test panel
Air bladder
Vertical links
(load cell)
Reaction beam
Displacement transducer
Prototype Panel
0
5000
10000
15000
20000
0 2 4 6 8 10
Deflection (in.)
Load (
lbs.)
Cracking Behavior of Prototype Panel
0
5000
10000
15000
20000
0 2 4 6 8 10
Deflection (in.)
Load (
lbs.)
12
3 4 5 6 78
Cracking Behavior of Prototype Panel
4 8 5 2 1 3 7 6
Load Versus Deflection - All PanelsLoad (
lbs.)
0
5000
10000
15000
20000
0 2 4 6 8 10
Deflection (in.)
Prototype
M-ties
Concrete
Bond
Initial Uncracked Stiffness
0
5000
10000
15000
0 1 2 3Deflection (in.)
Load (
lbs.)
Prototype
M-ties
Concrete
Bond
Initial Uncracked Stiffness
0
5000
10000
15000
0 1 2 3
Deflection (in.)
Load (
lbs.)
Prototype
M-ties
Concrete
Bond
Initial Uncracked Stiffness
0
5000
10000
15000
0 1 2 3
Deflection (in.)
Load (
lbs.)
Composite
Non-Composite
Prototype
M-ties
Concrete
Bond
Percent Composite Action, k
k
)100(exp
ncc
nc
II
II
k
Panel M-tie Bond Solid
Concrete Primary Variable
1 Prototype panel 100
2 M-tie connector 10
3 Solid concrete 92
4 Bond 5
Prototype Panel -Relative Wythe Displacement
Relative Wythe Displacement (in.)
0
5000
10000
15000
20000
-0.5 -0.25 0 0.25 0.5
Load (
lbs.) RD1
RD2
RD3
RD4
RD5
0
5000
10000
15000
20000
-0.5 -0.25 0 0.25 0.5
Relative Wythe Displacement (in.)
Load (
lbs.) RD1
RD2
RD3
RD4
RD5
Prototype
M-ties
M-tie Panel -Relative Wythe Displacement
Load Versus Deflection - All Panels
0
5000
10000
15000
20000
0 2 4 6 8 10
Deflection (in.)
Load (
lbs.)
Composite
Non-Composite
Prototype
M-ties
Concrete
Bond
Theor. cracking load = 3710 lbs.
Theor. cracking load = 12960 lbs.
Objectives
1. Investigate flexural behavior with a
focus on composite action
2. Investigate thermal performance
with a focus on thermal bridges
Thermal Performance of 2-wythe panels
solid area / panel area (ft2/ft2)
R-value
(hrft2F/Btu)
0
1
2
3
4
5
6
7
8
9
0 0.1 0.2 0.3 0.4
Thermal Performance of 2-wythe panels
solid area / panel area (ft2/ft2)
R-value
(hrft2F/Btu)
0
1
2
3
4
5
6
7
8
9
0 0.1 0.2 0.3 0.4
Thermal Performance of 2-wythe panels
solid area / panel area (ft2/ft2)
R-value
(hrft2F/Btu)
0
1
2
3
4
5
6
7
8
9
0 0.1 0.2 0.3 0.4
Typical two-wythe panels
Conclusions
1.Composite action comes mostly
from solid concrete regions
2.Solid concrete regions significantly
degrade thermal performance
Three-wythe
Panel
Two-wythe
Panel
Three-wythe
Panel
Two-wythe
Panel
Three-wythe Panel
Objective:
Develop three-wythe sandwich wall panels to exploit
the opportunities for improved structural and thermal
performance.
Three-wythe Panel Study
• Thermal performance
• Design studies
• Lateral load tests
• Prestress transfer tests
• Design recommendations and conclusions
Research Approach
0
20
40
60
80
100
120
140
0 24 48 72 96 120 144
Temperature Distribution - Two-wythe panel
120 F
20 F
Temp.
(F)
aab
ddcc
ee
b
T = 25 F
T = 125 F
x = 24 in.
a-a
d-d
e-e
c-c
b-b
0
20
40
60
80
100
120
140
0 24 48 72 96 120 144
Temperature Distribution - Three-wythe Panel
120 F
20 F
Temp.
(F)
aa
ff eegg
bb
T = 25 F
T = 125 F
ccddx = 24 in.
f-f
e-e
g-g
a-a
d-dc-c
b-b
Thermal Bridge Width, x1 (in.)
A-series
Two-wythe Panels
B-series
x1/2 x1/2
x1
C-series
12 ft
x1/2 x1/2
x1Three-wythe Panels
x1
R-value vs. x1 for A, B & C-series Panels
R-value
(hrft2F/Btu)
x1 (in.)
0
5
10
15
20
0 12 24 36 48
3-2-3 -2-3
2-2-3 -2-2
2-2-2 -2-2
3-1-3 -1-3
2-1-3 -1-2
2-1-2 -1-2
3-2-3A-series panels
B-series panels
C-series panels
• Thermal performance
• Design studies
• Lateral load tests
• Prestress transfer tests
• Design recommendations and conclusions
Research Approach
• fci’ = 3500 psi, fc’ = 6000 psi
• Prestressing strand
7 wire low-relaxation prestressing strand - Grade 270
strand diameter = 7/16 in, Area = 0.115 in2
fu = 270 ksi, fy = 245 ksi, Ep = 28500 ksi
fpi = 0.7fu, R = 0.85
• Mild steel
fy = 60 ksi
• Wind load = 32 psf
Design Parameters
144 in
22
22
2
Flexural Design
2-2-2-2-2 panel
0
5
10
15
20
25
30
35
20 30 40 50 60 70 80
Span length (ft)
Nu
mb
er
of str
an
ds
1.2Mcr
0.9Mn
Mf
0
5
10
15
20
25
30
35
30 40 50 60 70 80
Span length (ft)
Nu
mb
er
of str
an
ds
3-2-3
2-1-2-1-2
2-1-3-1-2
3-1-3-1-3
2-2-2-2-2
2-2-3-2-2
3-2-3-2-3
3-2-3
Flexural Design
0.0
0.5
1.0
1.5
2.0
0 20 40 60 80
Span length (ft)
Deflection (
in.)
3-2-3(C)
2-1-2-1-2
3-1-3-1-3
2-2-2-2-2
3-2-3-2-3
Code-Specified Deflection Limitations
3-2-3
0.75 in.
deflection limit
L/480
• Thermal performance
• Design studies
• Lateral load tests
• Prestress transfer tests
• Design recommendations and conclusions
Research Approach
6’- 8”
Test panel (2/3-scale)35’ span, 7-7/16 in. dia. strands, 4 strands 4’ debond
Prototype panel
52.5’ span, 16-7/16 in. dia. strands, 8 strands 6’ debond
10’
3-1.5-3-1.5-3
2-1-2-1-2
Lateral Load Tests
Lateral Load Tests
• 6’- 8” 35’ span (2/3 scale)
• Two cross sections
• Uniform load over span
Panel 1
Panel 2
Test Set-up
Test panel
Air bladder
Vertical links
(load cell)
Reaction beam
Displacement transducer
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
0.0 2.0 4.0 6.0 8.0
Deflection (in.)
Tota
l lo
ad (
lbs.)
Panel 1
Panel 2
Load vs. Deflection for Panels 1 and 2
Composite Behavior
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
0.0 2.0 4.0 6.0 8.0
Deflection (in.)
Tota
l lo
ad (
lbs.)
Panel 1
Panel 2
Non-composite panel
Composite panel
Panel 1
Panel 2
k= 79 % 91 %
k= 94 % 97 %
Test FEM
Composite Behavior
Theoretical & Experimental Cracking Loads of Panel 1
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
0.0 2.0 4.0 6.0 8.0
Deflection (in.)
To
tal
loa
d (
lbs
.)
Crack #2, a=4.0, with Iexp=2501 in.4
Crack #3, a=4.8, with Iexp=2501 in.4
100% composite, Ic=3115 in.4, a=7.5
0% composite, Inc=235 in.4, a=7.5
79% composite, Iexp=2501 in.4, a=7.5
ft=afc’
Conclusions
Thermal Performance of the Three-wythe Panel:
• Improved thermal peformance compared with two-wythe panel.
Behavior under Lateral Loads:
• Reliable composite behavior due to solid concrete connection
between wythes.
• Ductile flexural behavior under the lateral load.
• Early flexural cracking at service loads (same as two-wythe panel).
More Information on Three-wythe Panel
Lee, B.J., Pessiki, S., “Experimental Evaluation of Precast Prestressed
Concrete Three-Wythe Sandwich Wall Panels,” PCI Journal,
Precast/Prestressed Concrete Institute, Vol. 53, No. 2, March-April
2008, pp. 95-115.
Lee, B.J., Pessiki, S., “Design and Analysis of Precast Prestressed
Concrete Three-Wythe Sandwich Wall Panels,” PCI Journal,
Precast/Prestressed Concrete Institute, Vol. 52, No. 4, July-August
2007, pp. 70-83.
Lee, B.J., Pessiki, S., “Thermal Performance Evaluation of Precast
Concrete Three-wythe Sandwich Wall Panels,” Energy and Buildings,
Vol. 38, Issue 8, August 2006, pp. 1006-1014.
Structural and Thermal Performance of
Precast Concrete Sandwich Wall Panels
Stephen Pessiki
Professor and Chairperson
Department of Civil and Environmental Engineering
Lehigh University
Bethlehem, PA USA
