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Walls have to resist the
uplift forces caused by
the pull of the wind.
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Walls have to resist the
shear forces that try to
push the walls over.
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Walls have to resist the
lateral force of the
wind that tries to push
the walls in and pull
them away from the
building
For uplift purposes, walls
are the intermediate link
between the roof and the
foundation below.
To resist uplift forces
walls have to have a
continuous load path that
can be achieved through the
use of metal connectors for
wood frame construction or a
combination of metal
connectors, vertical and
horizontal reinforcement,
and a bond beam at the top
of the wall for concrete
masonry construction.
Shearing forces
Walls are also subjected to
shearing forces that act in
the direction the wind is
blowing.
As wind blows on a wall, the
walls perpendicular to the
wall the wind is blowing on,
are subjected to these
shearing forces and are
called shear walls. Shear
walls are inherently
subjected to the shearing
and sliding forces.
Wood frame walls resist
these shearing and sliding
forces through the action of
the wall studs, the wall
sheathing (preferably
plywood), and a specific
nailing pattern.
Concrete masonry walls
resist these forces through
a combination of concrete
masonry units, mortar, and
grouted and reinforced
cells.
As a result of the walls
resisting the shearing
forces and being fixed at
the base, the walls are
subjected to an overturning
force, or the tendency to
rotate over.
For wood frame construction,
this force is resisted
through the use of a holdown
or tensions tied down.
Vertical reinforcement and
grouted cells resist the
overturning forces in
concrete masonry
construction.
Wind-Ready Walls
Finally, walls have to be
capable of supporting the
push and pull from the wind.
For wood frame construction,
studs have to be sized and
spaced accordingly to resist
the lateral forces, and have
to be securely supported at
the top and bottom plates.
Concrete masonry resists the
lateral forces by using
reinforcement in grouted
cells.
Visit
www.flash.org or call
toll-free (877) 221-SAFE for
more information about
protecting your home from
disaster.
Copyright 2004 Federal
Alliance for Safe Homes --
FLASH, Inc. All rights
reserved. |
