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Articles - cladding
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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.
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Inspection disclosed a delaminated
section of facing mix on a spandrel
panel |
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. |
The Benefits
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The benefits from implementing this
system are:
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Flexibility provision for
allowance of volumetric changes
in the vertical direction
related to changes in moisture
(shrinkage) and temperature.
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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. |
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