shear testing of precast concrete sandwich wall panel
TRANSCRIPT
Shear Testing of Precast Concrete Sandwich Wall Panel Composite Shear Connectors Taylor Sorensen, Jaiden Olsen, Dr. Marc Maguire
[email protected], [email protected], [email protected]
Test Method
Conclusion
References
1. Frankl, B. A., Lucier, G. W., Hassan, T. K., Rizkalla, S. H., “Behavior of Precast, Prestressed Concrete Sandwich Wall Panels Reinforced with CFRP Shear Grid,” PCI Journal, V 56, No 2, March 2011, 42-54.
2. Bai, F., and Davidson, J. (2015). “Analysis of partially composite foam insulated concrete sandwich structures” Engineering Structures 91, pp 197-209.
3. Woltman, G., Tomlinson, D., Fam, A., “Investigation of Various GFRP Shear Connectors for Insulated Precast Concrete Sandwich Wall Panels,” Journal of Composites for Construction, V. 17, September/October 2013, 711-721.
4. Naito, C. J., Hoemann, J. M., Shull, J., Saucier A., Salim, H., Bewick, B., Hammons, M (2011) “Precast/Prestressed Concrete Experiments Performance on Non-Loadbearing Sandwich Wall Panels.” Air Force Research Laboratory Report, AFRL-RX-TY-TR-2011-0021, Panama City, FL: Tyndall Air Force Base.
Research Significance Results Simplified Model
Figure1- Concrete Sandwich Wall Panel with Company A Connections
• The push for more sustainable engineering designs in the past 20 years has encouraged greater focus on thermally efficient connections for concrete wall panels (shown in Fig. 1). One of the most challenging aspects of insulated panel design is creating composite action between the concrete wythes, without causing a thermal bridge. Thermal bridging occurs when the thermally efficient foam is penetrated by a more conductive material like concrete or steel, and can greatly reduce the R value of the component.
• The objective of this research is to use existing information and new testing to develop general tools for use in every day practice to better generalize composite action in wall panels.
• Foam types used included Extruded Polystyrene (XPS), Polyisocyanurate (ISO), Expanded Polystyrene (EPS)
• Concrete reinforced by #3 rebar spaced at 6” on center
• Load applied to center wythe with relative displacement measured of inner wythe to outer wythe
• Specimens were each 3 ft. wide by 4 ft. tall • Each of four connectors manufactured using Glass Fiber Reinforced
Polymer (GFRP) but with differing processes and companies • Specimen depth consisted of three concrete wythes and two foam
wythes • Wythe dimensions were either 3”x3”x6”x3”x3” or 4”x4”x8”x4”x4”
Figure 2- Four Types of Push-off Concrete Test Specimens
Figure 3- Push-off Test Setup
• Many connectors maintained significant load while continuing to deform; others failed soon after they reached peak load
• Foam type and bond between concrete and foam interface had insignificant effect on strength or ductility, though unbonded specimens showed consistent reduction in capacity
• Analytical model developed using personal matrix analysis software • Model panels with only beam and spring elements
• Connectors provide less strength and stiffness with larger wythe thicknesses or when debonded
• Stiffness and strength were found to be unrelated and likely due more to the orientation of the connectors
• Simplified beam spring model is accurate as compared to literature • A triangular distribution of shear connectors is the most structurally
efficient (more connectors lumped toward ends) • Composite action was shown to increase with the increase of shear
connectors
Figure 4- Shear Load vs. Deflection for specimens
0
5
10
15
Load per Con
nector (kips) CA 3" SPECIMENS
NU EPS UB 3 NU EPS B 3 NU XPS UB 3 NU XPS B 3 NU ISO B 3 NU ISO UB 3
0
5
10
15
Load per Con
nector (kips) CA 4" SPECIMENS NUEPSB4 NUEPSUB4 NUXPSB4 NUXPSUB4 NUISOB4 NUISOUB4
0
5
10
15
Load per Con
nector (kips) CB 3" SPECIMENS
TSC XPS UB 3 TSC XPS B 3 TSC ISO UB 3 TSC ISO B 3
0
5
10
15
Load per Con
nector (kips) CB 4" SPECIMENS
TSCXPSB4
TSCXPSUB4
0
5
10
15
Load per Con
nector (kips)
CC 3" SPECIMENS TSX ISO 3B
TSX ISO 3c
TSX XPS UB 3
TSX XPS B 3b
0
5
10
15
Load per Con
nector (kips)
CC 4" SPECIMENS TSXXPSB4 TSXXPSUB4 TSXISOB4 TSXISOUB4
0
5
10
15
0.0 0.2 0.4 0.6 0.8 1.0
Load per Con
nector (kips)
DeflecKon (inches)
CD 3" SPECIMENS HK EPS UB 3 HK EPS B 3 HK XPS UB 3 HK XPS B 3 HK ISO B 3 HK ISO UB 3
0
5
10
15
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Load per Con
nector (kips)
DeflecKon (inches)
CD 4" SPECIMENS HKEPSUB4 HKXPSB4 HKXPSUB4 HKISOUB4
0
5
10
15
20
CA-‐EPS CA-‐XPS CA-‐ISO CB-‐XPS CB-‐ISO CC-‐XPS CC-‐ISO CD-‐EPS CD-‐XPS CD-‐ISO Ul#mate Load
per Con
nector
(kips)
3 Inch 3 Inch 4 Inch 4 Inch
Figure 5- Ultimate Load per Connector Comparison
Figure 8- Elastic Stiffness (KE) Comparison per Connector
0.00
2.00
4.00
6.00
8.00
10.00
12.00
CAEPS CAXPS CAISO CBXPS CBISO CCXPS CCISO CDEPS CDXPS CDISO
Shear Loa
d pe
r Con
nector
(kips)
3 Inch 3 Inch 4 Inch 4 Inch
Figure 7- Elastic Limit (FE) Comparison per Connector
0.00
50.00
100.00
150.00
200.00
250.00
CAEPS CAXPS CAISO CBXPS CBISO CCXPS CCISO CDEPS CDXPS CDISO
Conn
ector S
hear S#ff
ness
(kips/in)
3 Inch 3 Inch 4 Inch 4 Inch
• Elastic limit load (FE) and elastic stiffness (KE) identified visually
• Aside from strength and stiffness, other factors that should be considered include cost, ease of fabrication, and durability
0
10
20
30
40
50
60
0 0.2 0.4 0.6 0.8 1
Shear Loa
d (kips)
Shear Deflec#on (inches)
FE
KE
Fmax
Figure 6- Determination of Elastic Load and Stiffness
• Beam elements assigned individual concrete wythe properties, separated by distance between the concrete wythe centroids
• Springs placed to represent both connectors and insulation stiffness
• Equivalent point loads placed for corresponding applied pressure
• Model agreed with tested results, but only Connector B was modeled
• Further testing is currently in progress
0
0.5
1
1.5
2
2.5
3
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35
Pre
ssur
e (p
si)
Midspan Deflection (inches)
Bai and Davidson 2015 w/ Foam
PCS5 Specimen A
PCS 5 Specimen C
SAP Model w/o Foam
SAP Model w/ Foam
Bai and Davidson 2015 w/o Foam
Figure 9- Beam Spring Model
Figure 10- Deflection and Resistance Comparison (Naito)