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GFRC
Facade Panels with Steel Stud/Flex Anchor Connection
The Need
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The ability of building cladding systems to
perform successfully depends primarily on their proper design and construction. Current
practices in the United States utilize GFRC (Glass Fiber Reinforced Concrete) panels.
However, new problems are being detected with such systems. The facade and its attachments
(using GFRC) are not being adequately implemented to accommodate vertical and horizontal
differential movement between the panels and concrete frame which is resulting in failure
or cracking of the panels, and chipping off of the supporting concrete. This differential
movement results primarily from extensive GFRC shrinkage and creep, and thermal
expansion/contraction of the panels relative to the concrete frame. Thus, there is a need
for a system that provides freedom of movement under changing environmental conditions and
that establishes sufficient rigidity under gravity, wind, and seismic loads. |
Inspection disclosed a delaminated section of facing mix on a spandrel panel
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The Technology
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With proper design and construction, steel
stud-framed GFRC-skin cladding concept provides a versatile system for freedom of
expression in the architectural profile of facades. The system consists of GFRC skin
supported by light gage, cold formed, steel studs (Schultz et al. 1987). The flex-anchor
design concept can be used to support dead loads of the facade itself. It also neutralizes
wind loads, and seismic loads by resisting skin bending stresses. Most importantly, the
connection is designed to accommodate thermal expansion such that no buckling, opening of
sealed joints, excessive stresses in panel components, or other detrimental effects occur.
Also, this system offsets initial drying and shrinkage loads, and moisture movements due
to change of ambient conditions. |
This type of flex anchor is used to provide freedom of movement for GFRC cladding under
changing temperature and moisture conditions.
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The Benefits
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The benefits from implementing this system
are:
- Flexibility provision for allowance of volumetric changes in
the vertical direction related to changes in moisture (shrinkage) and temperature.
- Sound structural response against dead, wind, and earthquake
loads.
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Status
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The underlying technology is under wide
implementation in the USA. However, this specific system has not been adequately applied -
as presented here - in building construction to sufficiently produce the outlined
benefits. |
Barriers
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There is still no information available on the
overall implementation costs associated with such a system. Another important barrier lies
in the need for tight quality control and testing for the manufacturing of sufficiently
conforming stud/flex-anchor connections. |
Points of Contact
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Construction Technology Laboratories, Inc.
5420 Old Orchard Road Skokie, Illinois 60077-1030, Phone: (708) 965-7500, Fax: (708)
965-6541. |
References
- Schultz et al: 'Design Considerations for GFRC Facade Panels
Incorporating the Steel Stud/Flex-Anchor Connection', Proceedings of the 6th Biennial
Congress, October 20-23, 1987.
- Wright, Gordon: 'Inappropriate Details Spawn Cladding
Problems', Building Design and Construction, January, 1996.
Disclaimer Statement
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Neither the Construction
Industry Institute nor Purdue University in any way endorses this
technology or represents
that the information presented can be relied upon without further investigation. |
MMS06/LHM
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