New Hoist in Existing Construction 2

[dukeguy]

I'm a structural engineer serving in a role as owner's rep / authority having jurisdiction. One of our facilities is looking at installing new hoist equipment in an existing mechanical room. My conundrum involves a facility manager who wants to install a hoist that could exceed the capacity of the room. They provided calculations for new steel framing beneath the slab to support the hoist equipment, however, the designer only sized beams based on the LL of the mechanical room, *not* the max rating of the hoist.

The facilities manager assures me that the hoist is oversized and they will never need to lift anything that heavy. I feel like the code doesn't give me the luxury of assuming all future facilities managers would know this fact etc etc.

I was going to put my foot down and require the support steel to develop the full rating of the hoist (+ dynamic effects). However, I then started wondering if I'm just pushing the "weak link" out to the surrounding floor slab... would it be a problem if the hoist rating overloaded the adjacent floor slab (i.e. if they roll something heavy that the hoist & hoist support steel can handle into the corner of the room and now there's a slab problem) I know the live load section of IBC/ASCE references designing to the max of either the area load or the specific equipment weights. If I'm introducing a hoist into a mechanical room, is the "equipment weight" now the rating of the hoist, and that room's entire floor needs to be designed accordingly (rather than just the immediate hoist support framing) Or is that interpretation overkill?

Thanks!

 

[dik]

...that, or rate the crane for the capacity of the framing in large lettering...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[SlideRuleEra]

I'm a structural engineer serving in a role as owner's rep / authority having jurisdiction.
My conundrum involves a facility manager who wants to install a hoist that could exceed the capacity of the room.
...would it be a problem if the hoist rating overloaded the adjacent floor slab...
I know the live load section of IBC/ASCE references designing to the max of either the area load or the specific equipment weights.

IMHO, allowing the hoist to potentially overload the adjacent floor slab is not only a problem, it is unacceptable.

My employer was an electric utility (generation) and part of my job was to keep my fellow employees, contractors and consultants from doing something dumb. In heavy industry there is a good chance that a lot of different work will be performed simultaneously during an outage. That is when probability of a heavily loaded floor and a hoist making maximum lifts is greatest.

BTW, in these situations, don't go looking to "codes" for justification for a loop hole. Instead, base your decisions and actions on sound engineering principles plus inside knowledge of how the facility is used.

And, don't just tell the facility manager he can't do what he wants. Explain why and cover allowable options. Over time, if you develop a reputation for being "right", the manager (and others... word about you will get around within the company) will come to you for recommendations when something like this needs to be done.

http://www.SlideRuleEra.net

 

[JStephen]

I would consider dik's suggestion- but specifically, see if the manufacturer can furnish a de-rated nameplate to match.
Painting the capacity in big letters- 20 years from now, somebody will notice a little name plate that says higher and "correct" those big letters.