From: merrick group <merrickgroup(--nospam--at)compuserve.com>
Date: Thu, 6 Jan 2000 13:14:07 -0500
RE: Skewed (45 degree) shearwalls
No straps around corners.
It may not hurt and the cost is low so go ahead.
The top plates must overlap. Or use metal plate on top of topplate.
Detail a wedged cross section for one or both of the facing or
meeting corner studs.
If the corner has the weight of a stone fire place, I would rather
rely on additional straps that would attach directly to the body of
the fire place. It is conceivable that there may be a short top plate
of no use between the corner and the edge of fire place. I would
consider straps on diagonal blocking directing the pulling-out
tension directly into the body of the diaphragm.
The diaphragm shear may need more nailing to match a shear in
the diagonal wall. A triangular section of diaphragm at the
diagonal wall with interior edges perpendicular to framing could
be considered. The triangle body having heavier diaphragm nailing
and having the interior edges of the triangle collecting the
diaphragm load or capacity further inside the building.
If corners are not shear walls, then the triangular element is not
If a rigid diaphragm is considered.
If the corners are of shear walls. The principle axis of the whole
diaphragm may be skewed. The maximum shears will be with a
force skewed to the direction of framing. The principle axis is not
rotated, when the skewed shear walls have equal and opposite
skewed shear walls, balancing the affects of rotating the principle
axis. Get the Dennis Wish Program.
For flexible diaphragms.
If the diagonal shear wall is larger and stiffer than the walls
perpendicular to the shear wall line being considered, then as the
load is added the skewed wall will have an additional tilt. This
makes the diagonal wall very flexible and not rigid enough to
collect its tributary shear due to its other wise assumed relative
stiffness. I am not talking about the already reduced stiffness based
only on the 45 degree component.
With out correctly knowing the true stiffness it is best to design the
diagonal wall with out considering other inline walls, and design
the other inline walls with out sharing the load with the diagonal
David Merrick, SE