Temporary reduction of wind load
Temporary reduction of wind load
(OP)
Guys,
I am in the business of designing movable equipment similar to giant cranes. I am looking for a code that allows the temporary reduction of wind load design during transient conditions. For me, my transient condition is less than 5 minutes. Both before and after the transient I will extend outriggers and will be able to withstand at least 100km/h plus LRFD safety factor. But many times during the day I have the need to retract, move for 5 minutes or less to a new site, extend again.
Does anyone have any idea of a Canadian or US code that allows temporary reduction to say, 50% of wind load during those 5 minutes? I found a German DIN standard 1055-4 that allows 50% reduction for transient condition up to 3 days. But that's German.
Thanks!
I am in the business of designing movable equipment similar to giant cranes. I am looking for a code that allows the temporary reduction of wind load design during transient conditions. For me, my transient condition is less than 5 minutes. Both before and after the transient I will extend outriggers and will be able to withstand at least 100km/h plus LRFD safety factor. But many times during the day I have the need to retract, move for 5 minutes or less to a new site, extend again.
Does anyone have any idea of a Canadian or US code that allows temporary reduction to say, 50% of wind load during those 5 minutes? I found a German DIN standard 1055-4 that allows 50% reduction for transient condition up to 3 days. But that's German.
Thanks!






RE: Temporary reduction of wind load
RE: Temporary reduction of wind load
RE: Temporary reduction of wind load
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ASCE's "Design Loads on Structures During Construction, SEI/ASCE 37-02".
<https://www.asce.org/bookstore/book.cfm?book=4242>
RE: Temporary reduction of wind load
http://www.babcock.com/pgg/tt/pdf/BR-1670.pdf
I realize this is not exactly a regulatory code that you are looking for, but B&W is well qualified to speak on this issue. Raising a steam drum at an electric power station can take several days.
boo1 - Thanks for bringing up the California Falsework Manual reference, I had forgotten about that one.
www.SlideRuleEra.net
RE: Temporary reduction of wind load
RE: Temporary reduction of wind load
RE: Temporary reduction of wind load
I am not familiar with the Canadian Code, the IBC code used in the US though did away with the general allowable stress increase for transient loads with exception of wood structures. This is dealt with in Section 1605.3.11.
Eric McDonald, PE
McDonald Structural Engineering, PLLC
RE: Temporary reduction of wind load
Underslung Type)". There is a 2002 Addenda to the document. I reviewed the document at Linda Hall Library and copied a few pages. Wind loads are typed as operating wind loads, stored or out of service wind loads, and extreme (tornado) wnd loads. ASCE 7 is referenced for stored wind loads. Section Num-III-8000 describes load cases, design criteria and allowables. (They use a percentage of yield for some stress or use AISC ASD and then modify the result.)