While self-tapping screws are not yet directly addressed in either NDS 2018 or CSA O86, ASSY carbon steel self-tapping screws have been awarded product approval reports for compliance to NDS 2018 (ICC ESR-3178, ICC ESR-3179) and CSA O86 (CCMC 13677-R). Included in these product approval reports are proprietary design values calibrated to each code. CCMC 13677-R was recognized in the recent edition of the CSA O86 commentary under Cl.12.6.5. The commentary notes that (due to extensive testing) ASSY carbon steel self-tapping screws are assigned a resistance factor Φ = 0.9 in CCMC 13677-R for withdrawal resistance, giving them an increase of approximately 50% over lag screws, which use a resistance factor Φ = 0.6.
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