Each month, the Cold-Formed Steel Engineers Institute (CFSEI) publishes answers to cold-formed steel (CFS) framing questions submitted through its 1-800-79STEEL hotline. This recent CFSEI FAQ addresses temporary out-of-plane bracing for load-bearing CFS walls during construction.
CFSEI Hotline: 1-800-79STEEL
Allowable Screw Shear and Tension Capacities
Question
Why does the “Allowable Screw Shear and Tension Capacities” table in the SFIA “Technical Guide for Cold-Formed Steel Framing” list the Fy and Fu values the same (i.e., 33 ksi) for 18, 27 and 30 mil material thicknesses?
Answer
Material thicknesses 18, 27, and 30 mil steels are used for nonstructural framing applications. The North American Standard for Cold-Formed Steel Nonstructural Framing, AISI S220, Section A3.1 stipulates the following:
ASTM A1003 Table 3 (Mechanical Properties, Base Metal) lists minimum mechanical properties requirements for the various steel grades. However, Table 3 does not list minimum requirements for the tensile strength of NS grade steels. The tensile strength is needed to calculate screw capacities per AISI S100 Chapter J. Thus, the SFIA catalog conservatively provides allowable shear and tension capacities based on the minimum required yield strength for NS grade steel.
1.800.79STEEL
If you have any cold-formed steel (CFS) questions, contact CFSEI experts online or call CFSEI Hotline at 1.800.79STEEL.
Read more CFSEI “FAQ of the Month” questions and answers here:
CFSEI Hotline: 1-800-79STEEL
Cold-Formed Steel Engineers Institute
The Cold-Formed Steel Engineers Institute (CFSEI) comprises hundreds of structural engineers and other design professionals. Together, they are finding a better way to produce safe and efficient cold-formed steel (CFS) designs for commercial and residential structures. CFSEI members develop industry standards and design methods. CFSEI issues technical bulletins, organizes seminars and provides online training so that engineers and design professionals can improve their knowledge and skills. CFSEI is part of the Steel Framing Industry Association (SFIA) family. For more information, visit www.cfsei.org.
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