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Very basic civil engineering question
I'm designing a concrete pad for an elevator that will be built on the outside of a two-story concrete block building. I would like to get some feedback on the design of the pad. Specifically, I would like to know the following.
* Should I have a foundation around the outside that goes below the frost line, to keep the pad stable? The frost line defined in the building code in this jurisdiction is 18 inches below ground level, so that would not be difficult or expensive.
* How thick should the floor part of the pad be?
* Anything else important I might have missed.
[U]Background and Detail[/U]
I work for the company that builds the elevators, but we are all mechanical and electrical engineers and have no experience with concrete and structures. We have the agreement of the building owner to install the elevator, but he doesn't want us to pin the concrete to his structure since it is only temporary. (It's a test and development unit.) So it will be a stand-alone pad adjacent to the building. However, we also want to minimize any relative movement between the building and the elevator, so we want to be sure that the concrete pad settles or moves around as little as possible.
I've attached a sketch of the proposed pad. It has a raised lip about 8 inches high on the three sides that aren't adjacent to the building, so that the elevator sits in an 8 inch deep pit. The elevator rail system, which supports all the weight, sits on the raised rectangle on the floor of the pit. The pit floor has a slight slope, for drainage, which goes out to ground through a small pipe. There is an enclosure that sits on the top of the lip, and the mass of the enclosure is transferred to the concrete through the four corner posts.
Here are the approximate masses.
Elevator, rail system, and payload: 2,500 kg/5,400 lb
Enclosure: 1,900 kg/4,200 lb
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