concrete rib dome calculations engineer

[netnimble]

I need some help from a civil engineer on a concrete rib dome building I want to build. This is too complicated for the people I've contacted locally. I could use some pointers just to make sure the design isn't crazy. I could use some advice on how to hire someone to help me. thanks.

 

[ishvaaag]

Well, I surmise then you have to think of someone to whom you may have access not so locally to hire him or her. Ask in the institutions or professional associations or universities there who could be able to do such work and is licensed, active and for hire in the field, or just look in any kind of professional services guides.

Then, for the work itself, it is not as difficult as it may seem it one doesn't go for unrealistically thin thicknesses. But the structural designer will put these things in order.

 

[ishvaaag]

errata

... if one doesn't go...

 

[MiketheEngineer]

If you can't find them locally - look nationally. Many (most) things today can be handled electronically.

 

[DTGT2002]

Where are you located?

 

[netnimble]

I'm in Sacramento. I've searched on the internet, and I can find "high end" engineering firms to design million dollar concrete buildings and freeways, etc, but people that cater to my low-budget generally will only do traditional homes.
I expected to have this problem, makes innovation a challenge doesn't it? Apparantly in rural Texas you can build anything you want, not so in California.

 

[hokie66]

Suggest you do some research on Binishells. Beware though, some of them have collapsed.

 

[netnimble]

thanks for the binishell reference, have not seen that before, interesting to raise the wet concrete. I've studied the monolithic technique. binishell seems to have a similiar problem though in that it can't be built incrementally as my design.

 

[ToadJones]

Maybe you should call Richard Buckminster Fuller

 

[flash3780]

Seems like a welded steel structure might be more economical. I assume there's a skin over it?

I think you'd be hard-pressed to design this building without some higher-end engineering effort. The folks who do engineering assessments for houses aren't going to do as detailed of an assessment as is necessary.

Perhaps you could find an angel investor to fund the effort and you could fund the development and marketing in that way.

 

[netnimble]

The picture just shows the ribs of the dome. Between the ribs will be filled in, so the dome will be a complete solid structure.
Steel would probably be cheaper as a rib structure.
One key is this will be made using lightweight concrete, which provides the insulation needed. So basically the entire structure is made of a single simple low-cost material.
The ribs essentially provide the base structure, and then the forms to complete the dome.

It seems many work on designs to build structures FASTER, which usually also means cheaper. My design is to build it SLOWER, which in effect is like using leverage, a longer build time with less immediate effort, and less man, material and equipment at once.

I primarly want to build this one house for myself, but certainly it can be easily duplicated once the full engineering specs are done. In particular, one could prefab the ribs and deliver them onsight and have just the fill done locally, like some prefab home business do for other types of homes, e.g. deltec

I just might try to contact a local bazillionaire developer and he can fund the engineering costs and do prefab, he invests in lots of startups, a friend used to work for one of them.

 

[hokie66]

To build one structure like this will be prohibitively costly, due to startup costs as you have realized. Prefabrication of the ribs requires making new moulds, and that is expensive. I doubt the practicality of handling such thin concrete ribs, as they would be cast flat and have to be lifted. Craneage at the site may also be a deal breaker. Sorry to be a naysayer, but I don't see a future for this system.

 

[netnimble]

hokie66, do you have any calculations to back up your opinion?

 

[hokie66]

Nope, just 45 years experience. You may not think that is a good thing. Maybe a starting point would be to talk to a precaster in your area.

 

[netnimble]

Well, here is some data, the ribs weigh less than 2,000 lbs, no crane is needed, heck a floor jack can do it..
Only a single mold is needed all the ribs are the same for a dome.
Once again, this is done slowly. Doing 75 ribs one a day takes almost 3 months! But by the time the last one is done, they have aged and hardened, which is needed anyway.

I can figure out all the calculations, buy if I must pay for
an engineers approval, they will have to do their own anyway.
The static load is not complicated, but I must account for Earthquakes

 

[hokie66]

With ribs only 4" thick and cast flat, I doubt that you would be able to erect them without cracking the panels. Another issue will be temporary bracing for stability during erection. How would you fill in between the ribs? Formwork and cast in place concrete or some type of precast planks?

 

[ToadJones]

Is this thesis work?