Integrated Buildings & Structures

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  • 1.  Hanger Impact Loads in ASCE 7

    Posted 09-24-2019 05:34 PM
    In ASCE 7-05 Sec. 4.7.2, for hangers for floors and balconies a 33% impact factor is to be applied to the load.

    In ASCE 7-10 Sec. 4.6.3 any mention of hangers has been omitted.

    Why?

    Does the omission have something to do with the section referring to "machinery" and the hanger provision being open to broad interpretation?  Did the impact factor move somewhere else in the standard?

    Thank you!

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    Chad Morrison P.E., M.ASCE
    Professional Engineer
    Greenville RI
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  • 2.  RE: Hanger Impact Loads in ASCE 7

    Posted 10-29-2019 04:47 PM
    In a more general scope, it appears the load factor for Wind changes from 1.6 in ASCE 7-05 to 1.0 in ASCE 7-10.  What is the reasoning for this?  The change appears to be offset by a change in the importance factor.  Thank you!

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    Chad Morrison P.E., M.ASCE
    Professional Engineer
    Greenville RI
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  • 3.  RE: Hanger Impact Loads in ASCE 7

    Posted 10-30-2019 09:18 AM
    Edited by Tirza Austin 10-30-2019 09:17 AM
    ASCE7-10 wind loads are ultimate loads; ASCE 7-05 wind loads are unfactored​/service level.

    If you're using ASCE 7-10 winds, you need to scale them down to unfactored loads when checking wind deflections.

    IMO, I see this change as causing a lot of confusion among some engineers and a lot of owners (ie. 'why did wind speeds increase?').  It's tough to explain to owners.  It also causes confusion when coordinating with product vendors (ie. MEP vendors and window and door vendors). 

    I've taken to putting both the ultimate and the nominal wind speeds on drawings.  Ditto for clarifying whether listed C&C pressures are ultimate or service level.



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    Greg Thein, PE
    Cleveland, OH
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    Original Message


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