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[SEAOC] Plywood Shear Walls on Metal Studs and lightweight metal roof trusses

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I previously reported that a SEAOSC Ad-Hoc committee was issuing a draft
for cyclic testing of metal stud walls. This was not quite correct. I
received a copy of the current draft this afternoon and provide the
following Scope of work as noted on the report. Please note that this is a
procedure only - for the cyclic testing of any framed wall system - not
limited to wood and steel stud. The report is a current draft only. To
obtain a copy, I suggest you contact SEA of Southern California and request
the following title dated January 18, 1996 (11 pages total):


"Standard Method of Cyclic (Reversed) Load Test for Shear Resistance of
Framed Walls for Buildings
Based upon ASTM Standard E 564-76 (Reapproved 1984)

1. Scope
1.1 This method is designed to evaluate the shear stiffness and shear
strength of a typical section of a framed wall system, including its shear
connections and hold-down connectors, under cyclic (reversed) load
conditions. 
1.2 This method may involve hazardous materials, operations, and equipment.
This method does not purport to address all of the safety problems
associated with its use. It is the responsibility of whomever uses this
standard to consult and establish appropriate safety and health practices
and determine the applicability of regulatory limitations prior to use."

Essentially, this is a proposal for establishing testing criteria for any
framed shearwall system. Once established and accepted, this criteria can
be used to obtain working stress values for various shearwall systems
including steel stud and wood frame.

What I interpret from this is that there is no conclusive standard for the
evaluation of shear wall systems under cyclic (seismic) load. Although the
values published by ICBO appear to be the most current allowable stress
which we are allowed to use, these are applicable to wood framed systems
only.

Once the Ad-hoc committee report is approved, appropriate testing can be
done by the AISI and other interested proprietary suppliers to determine
allowable values for each system.

Finally, it appears to me that there are really two choices at the present
for the design of plywood shear panels on steel stud. That is:
1. Use the values provided by APA under the research report #154 (John R.
Tissell, Structural Panel Shear Walls, APA Tacoma Washington, May 1993) for
wind governed loads only.
2. Disallow the use of steel studs with plywood sheathing for designs
governed by seismic. The steel stud system may be able to be designed as a
braced framed system rather than accounting for the capacity of plywood and
screws.
3. Design for alternative shearwall elements.

Does this sound reasonable, or is there any other information out there?

Finally, are there any standards for the manufacturing of lightweight metal
roof trusses to be used on steel stud walls. These would be trusses spaced
at 24" on center. 

You comments are greatly appreciated.
Sincerely
Dennis S. Wish PE

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