Elevator in 3-story Wood
Elevator in 3-story Wood
(OP)
Folks,
This is my first rodeo with an elevator in a multi-story all wood framed building (Endura 3500# model by Thyssen Krupp). A few questions:
1. In the past with steel structures I didn't care about the hoist beam reaction in terms of how often it is utilized. The steel was good whether it was a constant load or a onetime thing. Somewhere I think I heard that the hoist load is a one time deal (or rarely needed). I'm thinking wood creep, etc. Am I imagining hearing that?
2. Arch has the 2.5" steel stud shaft walls that I'm surrounding with multiply LVLs at the floor levels. The rail forces seem small (3500# elevator) based on the submittal I have. Is this what is typically done?
3. Does anyone do the hoist beam out of wood, or just do steel? Im considering running steel tubes in the walls the entire structure height with a steel beam and moving on. (Of course, bracing the steel column at each floor level too.
4. Any other things I need to be thinking through?
Thanks,
Nick
This is my first rodeo with an elevator in a multi-story all wood framed building (Endura 3500# model by Thyssen Krupp). A few questions:
1. In the past with steel structures I didn't care about the hoist beam reaction in terms of how often it is utilized. The steel was good whether it was a constant load or a onetime thing. Somewhere I think I heard that the hoist load is a one time deal (or rarely needed). I'm thinking wood creep, etc. Am I imagining hearing that?
2. Arch has the 2.5" steel stud shaft walls that I'm surrounding with multiply LVLs at the floor levels. The rail forces seem small (3500# elevator) based on the submittal I have. Is this what is typically done?
3. Does anyone do the hoist beam out of wood, or just do steel? Im considering running steel tubes in the walls the entire structure height with a steel beam and moving on. (Of course, bracing the steel column at each floor level too.
4. Any other things I need to be thinking through?
Thanks,
Nick






RE: Elevator in 3-story Wood
Short answer; don't do it. Long answer is you can do this but it's likely easier to just use concrete or a masonry shaft. Mostly for fire protection reasons but structural as well. Check out my topic here: http://www.eng-tips.com/viewthread.cfm?qid=378935
A google search can turn up a lot as well.
1. I would consider it infrequent enough to not worry about creep.
2. I used a multi-ply LVL built-up using SDS screws. The biggest issue I faced was not strength but deflection, make sure the rail supports are sufficient. My elevator was one of the ones without a machine room so you may have some different loads than I did. However, I remember my rail loads weren't that large either. Definitely check those deflection limits though, they're really small. The elevator manufacturer can provide a lot of design help.
3. I would only try this with a steel hoist beam. Trying to do that out of wood seems like a recipe for disaster. Steel beams for the rail supports would be better but as I found you can do it with wood for the rail supports.
4. FIRE! Fire protection is critical. The shaft must be fire rated per the code and this typically will be an unbroken fire barrier on the roof, walls, etc. This is very hard to detail with plywood and gypsum wallboard but can be done.
Professional and Structural Engineer (ME, NH)
American Concrete Industries
www.americanconcrete.com
RE: Elevator in 3-story Wood
1. Thanks for the google/eng tips links. I actually looked up some of those and my main question is in regards to the frequency of the hoist beam load which I couldn't find.
2. So the arch (see below pic) is showing those 2.5" steel shaft wall studs. I plan to put a 2-ply LVL right behind that. Do they attach the rails to through that wall to the LVLs on either side? I'm not sure how that all works, but I want to have something for them to attach to. The stud walls are outside of my scope (IE archs).
3. How do you calculate the deflection you mention? If they connect to my LVL's at the floor, it won't be any more than the story drift because it's all tied to the diaphragm, which it will be anyway. Maybe I'm missing something?
4. Fire protection is architect's baby. I want to be accommodating though.
Attached is the arch plan.
Thanks!!!!!
RE: Elevator in 3-story Wood
Professional and Structural Engineer (ME, NH)
American Concrete Industries
www.americanconcrete.com
RE: Elevator in 3-story Wood
RE: Elevator in 3-story Wood
2. I had them attach the elevator to the LVLs through a steel plate (which was provided by the elevator manufacturer) and a wood squash block with SDS screws.
3. I used the NDS deflection equations for a wood member. However, the issue I found is there is no research (or at least none I found) on nail/screw slip between plys which will add to the deflection. To hopefully remove this ply-slip deflection I had them glue the plys together as well as screw them.
4. Yeah, as long as the arch can provide the fire rating needed you can get an acceptable elevator shaft. About the biggest problem will be the penetrations where the rails go through the firewall to bolt onto your LVLs. This can be an issue which I never 100% resolved (I also wasn't in charge of the fire protection design).
Professional and Structural Engineer (ME, NH)
American Concrete Industries
www.americanconcrete.com
RE: Elevator in 3-story Wood
RE: Elevator in 3-story Wood
Thankfully njlutzwe is going to use LVLs and metal studs so hopefully his shrinkage effects will also be minimized.
Professional and Structural Engineer (ME, NH)
American Concrete Industries
www.americanconcrete.com
RE: Elevator in 3-story Wood
RE: Elevator in 3-story Wood
Professional and Structural Engineer (ME, NH)
American Concrete Industries
www.americanconcrete.com
RE: Elevator in 3-story Wood
RE: Elevator in 3-story Wood
RE: Elevator in 3-story Wood
Here's what I have shown now. A floor opening equal to the elevator shaft + width of the steel shaft wall studs. LVLs installed tight to that. I don't know how they will connect through the shaft wall yet. I'm sure it's possible, otherwise no one would manufacturer these shaft wall studs. I need to keep digging.
RE: Elevator in 3-story Wood
RE: Elevator in 3-story Wood
RE: Elevator in 3-story Wood
Yes I think that's it. I don't have project specific info yet. Just general info.
RE: Elevator in 3-story Wood
RE: Elevator in 3-story Wood
Also, they want a CMU pit instead of concrete. I don't see why not (grouted solid and reinforced of course), other than the waterproofing/waterstop detail. But then again, I've never seen a pit out of CMU. Anyone done a PIT out of CMU?
Thanks,
Nick
RE: Elevator in 3-story Wood
Professional and Structural Engineer (ME, NH)
American Concrete Industries
www.americanconcrete.com
RE: Elevator in 3-story Wood