DTIC ADA536509: Laboratory Testing of Architectural Exterior Wall Fins

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by  Defense Technical Information Center

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E Laboratory Testing of Architectural Exterior
Wall Fins

Leonard Zabilansky, William Burch, and Tommie Hall January 2009

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Approved for public release; distribution is unlimited.
COVER: Initial condition of mock-up covered in snow and ice of varying thicknesses from 2.5 to 7 inches; ice retention devices are
installed on the left side of the fin and the right side is used as the control.
ERDC/CRREL TR-09-1
January 2009
Laboratory Testing of Architectural Exterior
Wall Fins

Leonard Zabilansky, William Burch, and Tommie Hall
Cold Regions Research and Engineering Laboratory
U.S. Army Engineer Research and Development Center
72 Lyme Road
Hanover, NH 03755-1290
Final report
Approved for public release; distribution is unlimited.
Prepared for Skanska USA Building Inc.
Parsippany, NJ
Under Work Unit K42889
ERDC/CRREL TR-09-1 ii
Abstract: Ice and snow accumulation sliding from the exterior wall fins
installed on the New Meadowlands Stadium in New Jersey, future home
field for the New York Jets and New York Giants football teams, was rec-
ognized as a potential hazard to pedestrians. The objective of this test pro-
gram was first to determine if the hazard existed with the standard fin and
secondly to evaluate the performance of four ice retention devices (IRDs).
A mock-up was assembled using four fins in a vertical stack with different
angles. Four IRDs were tested: three were continuous strips and the fourth
was a truncated cone attached to the fin at 12 inches on centers. The IRDs
were mounted along the lower edge of the fin. To provide water drainage,
all the IRDs were spaced off the fin using 3/16-inch plastic spacers. To as-
sess the effectiveness of the IRDs under similar conditions, IRDs were only
installed on the fins on the left side of the mock-up while the right side, or
standard fin, was used as a control.
Testing confirmed that IRDs are needed to reduce the potential hazard of
large sheets of snow and ice sliding off the fin. The continuous barriers are
problematic because the drainage paths freeze and water travels to the end
of the fin to form large ice columns or because water travels over the top of
the barrier to form icicles with limited anchoring. The fourth option, the
truncated cone, provides discrete anchoring for the accumulation and al-
lows it to melt in place. The potential for large icicles to form still exists;
when they present a hazard to pedestrians they should be physically re-
moved.

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Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products.
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be construed as an official Department of the Army position unless so designated by other authorized documents.

DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR.
ERDC/CRREL TR-09-1 iii
Contents
Figures and Tables.................................................................................................................................iv
Preface....................................................................................................................................................vi
1 Introduction.....................................................................................................................................1
2 Laboratory Test Procedure............................................................................................................3
Fin designation.........................................................................................................................8
Test procedure..........................................................................................................................8
3 Observations.................................................................................................................................11
Shedding.................................................................................................................................11
Continuous IRDs.....................................................................................................................12
Discrete IRD............................................................................................................................22
4 Recommendations.......................................................................................................................27
Appendix A: Test 1...............................................................................................................................29
Appendix B: Test 2...............................................................................................................................41
Appendix C: Test 3...............................................................................................................................47
Appendix D: Test 4...............................................................................................................................59
Appendix E: Test 5................................................................................................................................73
Report Documentation Page
ERDC/CRREL TR-09-1 iv
Figures and Tables
Figures
Figure 1. All fins at 30° angle from horizontal with ice retention devices installed
(configuration 1).........................................................................................................................................3
Figure 2. All fins at 50° from horizontal with ice retention devices installed (con
figuration 2)................................................................................................................................................4
Figure 3. Top three fins at 50° from horizontal and bottom fin at 30° from horizontal with
ice retention devices installed (configuration 3).....................................................................................4
Figure 4. All fins at 30° from horizontal without ice retention device (configuration 4).....................5
Figure 5. All fins at 50° from horizontal without ice retention device (configuration 5).....................5
Figure 6. IRD option 1................................................................................................................................6
Figure 7. IRD option 2................................................................................................................................6
Figure 8. IRD option 3................................................................................................................................7
Figure 9. IRD option 4................................................................................................................................7
Figure 10. Icing of the model with a spray nozzle on a garden hose....................................................9
Figure 11. Snowmaking using a commercially available snow gun with an articulating
head.............................................................................................................................................................9
Figure 12. Deicing a vertical slot to isolate the modified side (“A”) from the control side
(“B”)...........................................................................................................................................................10
Figure 13. Ice cantilevered off the fin before breaking off as a large section....................................12
Figure 14. Piece of snow that fell off standard fin without the IRDs...................................................13
Figure 15. IRD option 1; with a frozen drainage path, the water is diverted to the end of
the fin........................................................................................................................................................14
Figure 16. Similar to IRD option 1 shown in Figure 15, when the drainage path is frozen,
the water is diverted to the end of the fin potentially forming a column of ice between
adjacent fin stacks...................................................................................................................................15
Figure 17. Top side of IRD option 3 showing the blocked drainage paths similar to IRD
options 1 and 2........................................................................................................................................16
Figure 18. Underside of fin A3 during icing tests..................................................................................16
Figure 19. Underside of fin A3 during snow test...................................................................................17
Figure 20. IRD option 2 modified by decreasing the 3/8-inch hole spacing to 3 inches
(IRD 2a).....................................................................................................................................................18
Figure 21. IRD option 2 with 1/2- by 2-inch-long slots 3 inches on center (IRD 2b)........................19
Figure 22. Top view of IRD 2a after 90 minutes of icing; the holes are iced over..............................20
Figure 23. Lower edge of IRD 2b after 90 minutes of icing; although the slots are still
open, they will eventually plug................................................................................................................20
Figure 24. End view of fin 3b with IRD 2a in the foreground and IRD option 2 in the
background...............................................................................................................................................21
Figure 25. Mechanical locking of the icicles by the panel joint on the leading edge of
the fin........................................................................................................................................................22
ERDC/CRREL TR-09-1 v
Figure 26. Buttons (IRD option 4) are attached to the fin at 12 inches on center............................23
Figure 27. IRD option 4. The buttons 12 inches on center are encapsulated in ice and
retain the sheet of ice (left), while the ice slides off without the IRD (right).......................................23
Figure 28. Separating the snow accumulation from the IRD to assess the size of the snow
pieces falling off the fin...........................................................................................................................24
Figure 29. Initial condition for Test 5 with IRD option 4 installed on the A side of the fin................25
Figure 30. Using radiant heaters to simulate solar heating of the top fins (A3 and A4)
while the bottom fins (A1 and A2) are shaded by the plywood...........................................................25
Figure 31. Icing conditions at the conclusion of heating fins A3 and A4 with radiant
heaters while shading fins A1 and A2....................................................................................................26
Tables
Table 1. Fin designation.............................................................................................................................8
Table 2. Test sequence............................................................................................................................11
ERDC/CRREL TR-09-1 vi
Preface
This report was prepared for Skanska USA Building Inc. headquartered in
Parsippany, NJ, contractor for the New Meadowlands Stadium in New
Jersey. The stadium, to be completed in 2010, will be the home field for
the New York Giants and New York Jets—the first facility built specifically
to accommodate two National Football League teams. The multipurpose
stadium will also be used for concerts and other entertainment and sports
activities.
The report was prepared under the general supervision of Dr. Thomas J.
Tantillo, Chief, Engineering Resources Branch, Cold Regions Research and
Engineering Laboratory (CRREL); Dr. Justin B. Berman, Chief, Research
and Engineering Division, CRREL; Dr. Lance D. Hansen, Deputy Director,
CRREL; and Dr. Robert E. Davis, Director, CRREL.
The Commander and Executive Director of the U.S. Army Engineer Re-
search and Development Center is COL Gary E. Johnston. The Director is
Dr. James R. Houston.
ERDC/CRREL TR-09-1 1
1 Introduction
Ice and snow accumulation sliding from the exterior wall fins installed on
the New Meadowlands Stadium in New Jersey, future home field for the
New York Jets and New York Giants football teams, was recognized as a
potential hazard to pedestrians. The objective of this test program was first
to determine if the hazard existed with the standard fin and secondly to
evaluate the performance of four ice retention devices (IRDs). A mock-up
was assembled using four fins in a vertical stack, in one of the following
orientations: all four fins at a 30° angle from the horizontal; all four fins at
50° from the horizontal; or the top three fins at 30° and the bottom fin at
50° from the horizontal. Four IRDs were tested: three were continuous
strips (options 1, 2, and 3) and the fourth was a truncated cone attached to
the fin at 12 inches on centers (option 4). The IRDs were mounted along
the lower edge of the fin. To provide water drainage, all the IRDs were
spaced off the fin using 3/16-inch plastic spacers. To assess the effective-
ness of the IRDs under similar conditions, IRDs were only installed on the
fins on the left side of the mock-up while the right side, or standard fin,
was used as a control.
The mock-up was subjected to five tests using ice, snow, or snow/ice ac-
cumulations. Icing of the model was done by successively spraying the
mock-up with water and allowing it to freeze before applying the next
layer. The snow cover was generated using a commercially available snow
gun while the room temperature was below 23°F. For the snow/ice accu-
mulation, the initial layer of dry snow was covered with saturated snow
and the excess water saturated the initial layer of snow. Once the required
accumulation was achieved, the refrigeration units were defrosted and the
room was cooled to freeze any available water and stabilize the accumula-
tion. Before testing, a narrow strip of the fin was deiced to assure that the
ice shedding processes on the left and right side of the fins were independ-
ent. The mock-up was subjected to wind (23 mph), localized heating, or
warming room temperatures while the melting/shedding process was
documented.
In the first test, it was apparent that IRDs were required because roughly
two-thirds of the accumulation on the standard (or control) fin slid off as
ERDC/CRREL TR-09-1 2

a single piece. This initial observation was reinforced with every subse-
quent test. The limitations of the continuous barriers (options 1, 2, and 3)
were also apparent as the drainage paths under these barriers froze. With
the drainage blocked, the upper side of the barriers served as a “gutter”
conveying the water to the end of the barrier and forming icicles at the end
of the fins. In the prototype, the IRDs are the full length of the fin; there-
fore potentially double the amount of water will be redirected to the end of
the fin. The volume of water redirected may triple because the stadium has
up to 12 fins in a stack compared to four in the mock-up. In the extreme
case, melt water off adjacent fins could form a column of ice in the narrow
gap between adjacent stacks of fins. Taking the scenario one more step, the
“gutter” would eventually fill with ice and water would flow over the bar-
rier, forming icicles along the leading edge of the fin and below the IRD.
The anchoring for these icicles could be limited because ice on the top edge
of the IRD could melt, disconnecting the icicles from the retained accumu-
lation.
Buttons (IRD option 4) are very simple, but also very effective in retaining
the accumulation. The discrete buttons allow the melt water to cascade
from fin to fin in the stack. The accumulation encapsulates the buttons,
which anchors the ice and snow in place. Spacing under the button pro-
vides additional mechanical locking of the accumulation to the buttons.
The panel joint along the leading edge of the fin provides an additional an-
choring point for the icicles. Snow and ice will slide between the buttons,
but the size of the pieces is controlled by the 12-inch spacing of the buttons
and the limited strength of the ice or snow to cantilever over the edge be-
fore it breaks off.
In summary, IRDs need to be installed on the fin to reduce the potential
for hazards to pedestrians. The continuous barriers (IRD options 1, 2, and
3) are problematic because the drainage paths freeze and water travels to
the end of the fin to form large ice columns or because water travels over
the top of the barrier to form icicles with limited anchoring. IRD option 4
provides discrete anchoring for the accumulation and allows it to melt in
place. The potential for large icicles to form still exists; when they present
a hazard to pedestrians they should be physically removed.