Elevator Hoist Beam 2

[KimWT]

Hi!

I have a question related with elevator shaft.
This project is precast concrete parking structure, which needs passenger elevators.
By mistake, precast elevator shaft was erected 9" lower than the roof height elevator shop drawings show.
I was told elevator hoist beam cannot be installed.

Is there really no extra room to tolerate 9" deviation?
How much space is actually allowable between hoist beam and motor or device attached to elevator?
I heard elevator industry does not allow any error, which is not practical in the construction industry.

I am looking forward to your advice.

Thanks!

 

[TehMightyEngineer]

I doubt anyone would ever design with a 9" tolerance on anything in a building, especially anything mechanical like an elevator. Last elevator shaft I worked on had the hoist beam hard up against the roof. I'm sure they can accommodate standard precast industry tolerances; which is not ±9 inches.

I'd say someone has some hard choices ahead on how to modify the as-built shaft.

Ian Riley, PE, SE
Professional Engineer (ME, NH, VT, CT, MA, FL) Structural Engineer (IL)
American Concrete Industries

https://www.facebook.com/AmericanConcrete/

 

[TehMightyEngineer]

As a more practical response; get the elevator railstack drawings from the elevator supplier (if you don't have them already) they should list the maximum upward movement and the required clear height overhead the elevator cab. Standard I've seen is 5 feet of overhead clearance. Perhaps this gives you some more space but I would still doubt they can accommodate 9 inches less than as designed.

Ian Riley, PE, SE
Professional Engineer (ME, NH, VT, CT, MA, FL) Structural Engineer (IL)
American Concrete Industries

https://www.facebook.com/AmericanConcrete/

 

[KimWT]

You can see small space between hoist beam and elevator motor.
Is it big enough to absorb 9" error?

 

[Agent666]

Just because there is room there doesn't mean that the lift guys will let you use it. Best to talk with them, room might be required for some of the running gear, ventilation requirements, or more likely room for the trolley hoist to actually lift the car during installation.

They like their tolerances, they fight tooth and nail for the specified shaft sizes, and then when you see the lift in the shaft you wonder why they need all this space around it. They are in the best position to say whether its an issue or not, then you have some clear direction on what you can and cannot do to address the issue.

 

[JLNJ]

Oftentimes there is a minimum clear height over the cab for the elevator overrun (so you don't get squished when you are riding on top of the cab and it goes up to the top floor).

Plus, elevator installers are notoriously difficult to work with.

 

[wannabeSE]

Check and see if removing the hoist beam after the elevator is installed is possible. This may solve the problem

 

[CANPRO]

Looks to me like they want 550mm/21.7” clear. You’re 229mm/9” short, so if you originally planned on giving them 779mm/30.7” or more, you should be good.

How did the precast get erected 9” short? That sounds like it would create a lot more problems than just an elevator beam.

 

[KimWT]

Thanks, JLNJ!

You raised realistic problem!

Elevator companies are very tough to work with.
When precast members are designed, they do not sometimes provide elevator shop drawings on time.
(Though Contract Drawings showed many details including specific dimensions regarding elevator shafts,
all my previous projects were redone by elevator companies.
I wonder why Architects provide very detailed info,
which could be ignored/changed by the elevator companies.)
Elevator companies insist hoist beam should remain though they use it once during elevator installation,
because they may use it when repair is required in the future.

Here is my question again: Is there REALLY no extra room to adjust? In my case 9"?

Thanks!

 

[jike]

Is there enough strength in the precast roof to rig directly off of? If not, can you install the elevator beam above the roof and rig to it thru a hole in the precast roof? Architect will probably insist that beam above the roof be removed after installation and before roofing installation. Opening in precast will also have to be patched.

Cost of extra work will have to be accessed to the entity that is responsible for the problem.

 

[jittles]

wannabeSE's point is a solid option to look at. It's not ideal, but I've had to do it once and it was OK'd by the elevator folks I was working with.

 

[KimWT]

Generally, which side is against eliminating hoist beam after elevator is installed?
Is it GC or elevator company? Why?

 

[jayrod12]

Both typically. It's additional work, so the GC doesn't want that added step. The elevator guys, as mentioned above, want it there in the event of further maintenance.

 

[hoshang]

Hi
Change gearless type motor to a gearbox motor.