Steel Lift Shaft Design Guidline

[fourpm]

Hi, I have a steel lift shaft to design in a 3 storey apartment. Can anyone give me any example or any recommendation of books on this because I haven't done one before. Thank you very much.

 

[dhengr]

Fourpm:
If lift in your area/vernacular means elevator (vert. transport system), why isn’t the elevator supplier designing the entire elevator running gear/lifting mechanism? Normally, they are responsible for this entire system, and they give us (structural engineers) reaction forces and allowable deflections of our components as they relate to their system. They have fairly significant factors of safety and design restrictions peculiar to the nature of their industry. I would want to know much more about the entire situation before I started designing some components for their system.

 

[fourpm]

Thank you dhengr. I agree with you that it is normally the supplier's job and that's why I have never designed before. That being said, I have seen some engineers designing the steel lift shaft on their plans and for the current job I am working on I was asked to provide the design as well. And I have no clue what to start like what loads and how it works or what consideration need to be taken as a start point. Can you simply walk me through the basic design procedure for this or do you have any example by any chance? Thank you.

 

[phamENG]

When you say "lift shaft" are you referring to all the mechanical parts as dhengr mentioned or is it just the space in the structure where the car goes up and down? In the states, when I say "elevator shaft" I'm just referring to the space and not the components. I account for their anchorage up front, and then double check shop drawings for the actual reactions during construction.

Around here, the architect will proportion the space based on a particular model of elevator they want. It's usually pretty easy to get an old set of shop drawings from the manufacturer for a similar installation, or you can run the numbers yourself. Here we have ASME 17.1, which gives guidance on the design of elevator cars, craddles, hoisting mechanisms, and shafts. I would suggest doing to both - try to get a set of "go-by" shop drawings from an elevator installer who wants the job and get your local elevator code and deconstruct their reactions to understand what's going on.

 

[LittleInch]

Finding out what type of lift would be a start point. At 3 storeys a hydraulic one might be used which has different issues to a cable type.

https://platformliftco.co.uk/news-pr/traction-versus-hydraulic-lifts-advantages-and-disadvantages

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[drbrainsol]

I assume what you have been asked to provide is the empty shell that the lift will be installed in. This can be steel, concrete or even masonry. I suggest the following process:

-get in touch with your client and work out which lift type / supplier they have in mind (if any). Also...how many people the lift is meant to be used by.
-get in touch with the supplier and ask them to provide some typical lift installation drawings and typical structure loads (for the lift type your client wants).
-using the supplier's info you should be able to design the lift shaft (don't be afraid to ask the manufacturer further questions if needed)

I have designed many lift shafts for public sector clients and the process above generally works well.

 

[dhengr]

Fourpm:
I must confess, I must have been sound asleep while writing my first post, I never gave a thought to the vert. shaft space that the elevator car rides up-n-down in. This is certainly more likely the your area of concern. And, Drbrainsol pretty well lays out the std. steps to get started. The elevator supplier will be concerned about things like deflections of their support points, about deflections of the vert. running rails and their attachments, about drift of the bldg., so that their mechanicals can run within these structural movement envelopes. Then, you have to be concerned about mating the rest of the structure, and its deflections and movements, with this somewhat stiffer structural element/area in the bldg.

 

[fourpm]

Thanks guys.
Sorry my bad. It is an empty steel shell like drbrainsol mentioned. I have found something similar online as below.

It is an indoor one. I will do what you guys say - ask the manufacturer for more information.
Before that, I am wondering how it works normally. Do I apply the machine self weight as point load at mid-span of the top beam under dead load load case and the people as live load and then I control the defection of the beam? What about the lateral load? Thank you.

 

[RicheS]

as mentioned previously, the supplier will give you the required design loads and locations of application. Many lifts these days serving 2 - 3 floors are self contained (ie don't require a separate motor room or are hydraulic with a base ram)

The main forces are transmitted through the connections between the car guide rails and counterweight guides. These are both vertical and horizontal. You need to look at these connections carefully as intermediate support is usually required between floors for the rails unless the supplier provides all this as part of the package. Also look at tolerances (typically the lift supplier will specify an envelope and I usually go +25mm above this to allow for tolerances)

Lifting hook or beam may be required at the head of the shaft to suspend the car for maintenance purposes. hydraulic lifts may exert loads at the pit base. Counterweights and Buffers also exert forces at base level.

Depending on the car size and system, the lifting eye at the top of the shaft my be up to 2000 kg (or more for very large lifts)

Horizontal forces from guides for an 8 person lift are typically low but if you need eccentric outriggers to support them you might have local secondary forces, moments etc

You need to know the overrun above the top floor..most lifts require clear headroom above the top pf the lift car. Again the manufacturers envelope will specify this. You will also need to look at the door details as the cross members may need to support door framing, door threshold, control panel etc. This is usually supported from secondary steel framing if not self contained.

This is typical:

 

[phamENG]

If your shaft is going to be steel framed, you need to get whatever elevator safety/design code governs in your area and read it carefully. ASME 17.1 has some very strict performance and testing requirements for the members involved. For instance, shieve beams supporting equipment for traction elevators is limited to the rather odd deflection limit of L/1666. Guide rails can't move more than 1/2" under design loading (I think that's the number - it's been a few months). I've seen engineers mistakenly take this as rail deflection only. It's not. It's cumulative. So the rail deflects, the brackets may deflect, the steel supporting the brackets deflects, etc. Elevators can be very temperamental machines that need pretty precise design in their shafts. Failure to get it right can cause really expensive fixes.