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Lifelines, safety belts, lanyards, and anchorage

Lifelines, safety belts, lanyards, and anchorage

(OP)
Hello All,
I am working on a project where tanker trucks will back into the building and the drivers will need to get on top of the trucks to clean them. I need to specify the loads that could enter the framing members of the structure at the points where the lifeline is anchored to the structure. I plan to design a cable to span between the mainframes of the pre-engineered metal building. This cable will be centered above the truck and run length-wise to it and allow the drivers to attach their body harnesses to. When I look at OSHA 1926.104(b), I see the anchorage of lifelines should be designed for 5,400 pounds. When I look at OSHA 1926.502(d)(15), I see the anchorage for attachment of personal fall arrest equipment shall be at least 5,000 pounds.

Do I design for 5,400 pounds or 5,000 pounds?

Thanks

RE: Lifelines, safety belts, lanyards, and anchorage

Not really either one. OSHA specifies "withstand" 5000 [or 5400], i.e. the anchorage is allowed to fail at 5100# [or 5500]. Thus in Structural Engineering terms, the terminations just need to be a 2kip connection using the AISC S.F. of 3.5. Suggest you use 3 or 4kip for the final design.

RE: Lifelines, safety belts, lanyards, and anchorage

1910.66 App C
I. "Personal fall arrest systems"
(c) Design for system components.
(10) Anchorages to which personal fall arrest equipment is attached shall be capable of supporting at least 5,000 pounds .....

1926.104(b)
Lifelines shall be secured above the point of operation to an anchorage or structural member capable of supporting a minimum dead weight of 5,400 pounds.

1926 Subpart R App G
(d)(15)
Anchorages used for attachment of personal fall arrest equipment shall be independent of any anchorage being used to support or suspend platforms and capable of supporting at least 5,000 pounds .....


I understand Duwe6's point that the force limit could be interpreted to be met without any factors, but the use of the term dead load in 1926.104 (b) is really unsettling for that purpose. Also I'm taking the PE soon and then eventually the SE and not knowing the actual value that needs to be designed for is not a fun place to be in for a test, even if in practice I can default to the more conservative value.

Anyone else looked into this?
Thank you

John-Jozef Proczka (Structural EI)

RE: Lifelines, safety belts, lanyards, and anchorage

I believe that "dead weight" in this case is meant to be a non-accelerating or static load. Further, I understand that the 5000 pounds is meant to be a default number for systems that are not engineered to withstand a fall arrest event.

RE: Lifelines, safety belts, lanyards, and anchorage

Fall Arrest Anchorages shall be capable of supporting a minimum force of
5,000 pounds per person attached; or shall be designed, installed, and used under the supervision of a qualified person. The best reference that would help you is the official copy of the ANSI Z359 Fall Protection Code from the American Society of Safety Engineers (ASSE) web site: www.asse.org

RE: Lifelines, safety belts, lanyards, and anchorage

"Fall Arrest Anchorages shall be capable of supporting a minimum force of 5,000 pounds per person attached"
Again, NOT 'normal' engineering. This anchor is allowed to fail at 5,005 lbs. Thus, per 'normal' engineering practice a 2kip connection meets this requirement.

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