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O • .. Anne McAteer-Brown, PE, SE amcateer-brown@ctengineering.com i CT ENGINEERING Inc. Structural Engineers • 180 Nickerson Street•Suite 302• •Seattle,Washington 98109• • Phone:206-285-4512 Ext 308• From: Phillip Hui [mailto:PHui@strongtie.com] Sent: Monday, February 24, 2020 11:23 AM To:Anne McAteer-Brown <AMcAteer-Brown@ctengineering.com> Cc:Justin R Fox<jfox@strongtie.com> Subject: RE: Simpson holdown HDU question Hi Anne, My colleague Justin asked me to look into your question.The capacities of the HDU holdowns are either governed by fastener shear calculations or assembly tested values. When the values are test governed,the load duration factor increase shall not be applied. For the HDU5 capacities published in ESR-2330, at Cd=1.0 the capacities for using 1.5" SDS and 2.5" SDS are 3500#and 5460#, respectively. The capacities published for the HDU8 at Cd=1.6 with 2.5" screws can be used for applications at Cd=1.0.The HDU8 used with 1.5" SDS screws capacity at Cd=1.0 is 5000#. This information is assuming all lumber is DF or better. Thank you, Phillip Hui,P.E. I Branch Engineer I Simpson Strong-Tie 1209-941-1139 Begin forwarded message: From:Anne McAteer-Brown<AMcAteer-Brown@ctengineering.com> Date: February 19, 2020 at 3:54:35 PM PST To:Justin R Fox<ifox@strongtie.com> Subject:Simpson holdown HDU question Justin: I have a question about the HDU series holdowns about the capacity of the holdowns when Cd = 1.0. RE Simpson Catalogue and ICC ESR 2330 DTT2Z states the capacity is the same for Cd = 1.0 and 1.6. Is the same true for HDU5 through HDU8.The footnotes say not to use duration factor of 1.6 again. (no double dipping) but is not clear on if you need to reduce the capacity for Cd = 1.0. But table 1B of ICC ESR has the same capacity for Cd = 1.33 and 1.6. C 73