Table 3.17D in the Wood Frame Construction Manual provides maximum shear wall segment aspect ratios for various wood and gypsum assemblies. Also see Special Design Provisions for Wind and Seismic Table 4.3.4. Typically, 3.5:1 is the maximum aspect ratio for design of blocked wood structural panel shear walls. For an 8′ tall shear wall, that would mean 27-1/2″ of…
The segmented shear wall method considers each full-height segment individually, and has hold-downs at the ends of each full-height segment. The perforated shear wall method only requires hold downs at the very ends of the shear wall length. Both methods are covered in various AWC standards including Special Design Provisions for Wind and Seismic and the Wood Frame…
Values of apparent shear stiffness, Ga, are tabulated in seismic columns of the SDPWS to facilitate calculation of seismic story drift in accordance with ASCE 7 Minimum Design Loads for Buildings and Other Structures. Values of Ga are equally applicable for calculation of the shear deformation component of total deflection due to wind loads up to the ASD wind…
AWC Wood Frame Construction Manual (WFCM) 2015 Edition is presently referenced in model building codes such as the IBC (International Building Code) and IRC (International Residential Code). The WFCM is an ANSI-approved document that provides engineered and prescriptive requirements for wood frame construction based on dead, live, snow, seismic, and wind loads from ASCE 7-10 Minimum Design Loads for Buildings and Other Structures. AWC Special…
For the perforated shear wall method, the internal vertical members are not designed to resist tension due to overturning; but for compression due to overturning the design force would be the same as would result from using a segmented shear wall method. See Special Design Provisions for Wind and Seismic and the Wood Frame Construction Manual. Read…
Guidance for this issue can be found in the commentary to the Permanent Wood Foundation Design Specification. The PWF commentary states in C5.4.5: Since nominal unit shear capacities for shear walls and diaphragms published in the Special Design Provisions for Wind and Seismic (SDPWS) Specification are based on short-term load duration, it is necessary to multiply…
No. The code will always take precedence over a standard because the code is adopted as law. However, IBC 2015 references SDPWS as follows: “2305.1 General. Structures using wood-frame shear walls or wood-frame diaphragms to resist wind, seismic or other lateral loads shall be designed and constructed in accordance with AF&PA SDPWS and the applicable…
Blocking can be oriented in either direction, so long as other requirements are met. Fastener penetration requirements vary with fastener diameter, so blocking orientation may require consideration to accommodate required penetrations.
Requirements for use of Omega are based on ASCE 7. SDPWS does not have specific provisions for Omega force design when ASCE 7’s two-stage procedure is used.
A diaphragm is not prescribed to be blocked for open front structures. The determination of whether blocking is needed is based on compliance with seismic drift limits and where added strength associated with blocked diaphragms is needed as part of the design.