Civil Engineering Reference
In-Depth Information
moments and forces in the members on the right side of the frame. The location of the
inflection points and distribution of forces can also be influenced by the following:
• Walls that include members with varying stiffness
• Walls that contain multiple openings with unequal header spans
• Walls that support skip loads or spans having loads with different magnitudes
• The installation of piers or columns with no effective lateral stiffness
• A flexible or failed foundation
• Headers having spans greater than the column heights
The determination of the force distribution through the wall is greatly simplified by
the use of a simple plane frame program, which will also account for all the issues noted
above. When the wall frame includes members with unequal pier widths, the wall must
be analyzed for lateral loads in both directions to determine the critical load case for
each pier member.
Relevant Information
Information on the design methods for simple span beams with composite sections
using plywood webs and lumber flanges and plywood stress-skin panels have been
available for decades. The following is a list of reports can be downloaded from the
APA—The Engineered Wood Association website or elsewhere on the Internet.
• APA-PDS Supplement 2,
Design and Fabrication of Glued Plywood—Lumber Beams
,
1992. This publication addresses the design and fabrication of composite beam
sections utilizing plywood webs with lumber flanges. The beams are fabricated
using adhesive-only web-to-flange connections. The methods outlined in this
publication are used as the basis for the design of the walls in this chapter.
• APA-PDS Supplement 3,
Design and Fabrication of Plywood-Stress-Skin Panels
,
1990.
4
This publication addresses the design and fabrication of glued composite
floor or roof sections utilizing plywood sheathing with lumber joists or string-
ers. The design examples include framing components with different moduli of
elasticity for calculating transformed sections.
• APA Research Report 151,
Plywood End Shear Walls in Mobile Homes
, 1988.
5
This
report addresses tests on shear walls with large openings. The header sections all
exceeded allowable aspect ratios. The results of the tests showed that the design
shear load was controlled by strength and not deflection. A second observation
from the first two wall tests showed that glued walls were only slightly stiffer than
the same wall without glue and that the ultimate load capacity was only increased
by about 21 percent for glued walls. A final observation noted that full composite
action is inappropriate for mechanically fastened walls without adhesives.
•
Design Guide for Plywood Webbed Beams,
2007.
6
The guide provides guidelines for
the design and fabrication of glued or nailed-only plywood beams with lumber
flanges.
• “Modelling Deformation in Nailed, Thin-Webbed Timber Box Beams.”
7
The
report provides the method of calculating the effects of nail slip on “nailed
only” semicomposite sections.
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