This Practice establishes a method for alternative shear wall systems to demonstrate equivalent seismic performance to light-frame shear walls constructed with wood structural panel (WSP) sheathing attached to dimension lumber framing using nails. Seismic equivalency for an alternative shear wall system is determined through comparison of seismic equivalency parameters (SEP) derived from cyclic in-plane racking tests to performance targets derived from tests of the reference shear wall system. This Practice considers only cyclic lateral loading, parallel to the plane of the shear wall. Design of walls with openings and performance for other wall functions, such as out of plane bending, vertical load capacity, combined shear and uplift, etc. are not considered. This Practice is applicable only to shear walls where all vertical load supporting elements are intact at the end of the in-plane lateral load test and remain capable of supporting gravity loads. Wall assemblies whose vertical load supporting elements buckle, fracture, or otherwise become incapable of supporting gravity loads during the lateral load test are outside the scope of this Practice. This Practice does not address height limitations, detailing restrictions, wall openings, derivation of design values for strength and stiffness, or other requirements and limitations that may be necessary for an alternative shear wall system. Further requirements shall be provided by a suitable product standard for the alternative shear wall system. This practice assumes that the stiffness or deformation of the alternative shear wall system can be estimated, and that design loads will be distributed among seismically equivalent wall systems based on their relative stiffness.
Shear wall systems that combine wood structural panels (WSP), wood framing, and sheathing nail fasteners, have favorable in-plane seismic performance attributes and a long history of satisfactory performance during earthquakes. Favorable seismic design coefficients are assigned to account for their inherent overstrength, drift capacity, and ductility. Where alternative lateral force resisting products (i.e. pre-fabricated shear wall products, new sheathing fasteners, sheathing products, or stud materials) are used in combination with or in lieu of the reference wood frame WSP shear wall system, the seismic performance attributes of the alternative product are frequently questioned.
Keywordsseismic; cyclic loads; earthquake, shear wall; lateral force; wood structural panel
The title and scope are in draft form and are under development within this ASTM Committee.Back to Top
Ballot Item Approved as D7989-2015 and Pending Publication