Monolithic Domes

OH God, I hope you're not building a sweat lodge!

I know nothing about this type of construction, but these guys might:

Monolithic Dome Institute - The Orion

Good Luck.

Lyn, its funny you should ask; as that's exactly what I'm up to. I'm going to charge $12,000, but for you, I'll make it $10,000; since you're the first one to step up. <g>

PS: Thx for the link.

Depending where you are, get to know the local code/permitting folks. Unless, of course, you are in the middle of a 100 acre compound.

Good luck.

You will find extensive resources here:

http://www.binisystems.com/dantebini.html

bwire, thx for the link. I never heard of such a system!

Wowsers flyinghigh, are you building another Super-dome out in the AZ desert? *LOL* -+*

Question for you: Are you building this dome yourself or just designing it or both? Designing it will depend ultimately on how it's going to be built.

Here's the short of how to build a dome one way. There are other construction methods.....

Have you even seen a precast concrete tank being constructed, such as a Natgun or Preload tank? That'd be the easiest way to construct a dome, especially with the span you're looking at!Natgun precast reinforced concrete dome panels...the entire dome being segmented into 3 or 4 circumferential rows with many pie slices, all made on the ground in very precise casting beds, one atop of the next slice and so on and so on....you end up with a stack of identical pie slices (actually not exactly a pie slice but more like truncated pie slices with 4 sides). Each row is separated by heavily reinforced circumferential rings that are later grouted solid.

Okay, the way Natgun does it is once they finished cast the dozens of pie slices they make sure all of the test results come back satisfactorily...and they make a batch of no less than 6 concrete test cylinders for each truck of premix....ditto with field tests done for each truck..air entrainment, time since dispatch, concrete temp., ambient air temp, & slump ,and how much mid-range plasticizer (in Oz.) added to the truck's load only at the job site and only at the express order by Natgun's Concrete Supervisor. The pie slices are then cured on-site for I believe no less that 28 days. they're protected too from the elements and accidental damage. Concrete hot boxes are provided on the site for all of the cast concrete cylinders, but taken at the correct times back to the lab for compression breaks.

Once the pie slices pass the muster of the Natgun Engineer's and site Supervisor as well as the project Engineer of Record, they are then erected upon steel towers (false works) much like scaffolding, but lots of them and fully adjustable at the base and summits. Once the pie slices are in correct position, the spaces between them are grouted solid and so are each of the 3 or 4 circumferential compression rings i mentioned above. After all of the grouted is completed then the concrete tension ring at the base of the dome (and at the top of the precast concrete walls) is wire wound with high tensile strength steel wire, then anchored and a shotcrete layer applied. This wire winding and Shotcrete may be done up to at least a dozen or so individual layers. With all of the tensile load applied down at the tension ring the end result is that the entire dome structure is then placed into compression....and whhhaaaa laaaaa you have a structurally sound dome!!!!

Formulas eh? I'll have to look for them...ummm dig them up and get back to you. It's not something you do every day!

For the span you're looking at, 4-inches of reinforced concrete may be too thin and you may have to bump it up to say around 5.5" to 6.6". there is a rule of thumb applied, but I don;t remember it off hand at the moment.

When designing a dome, make sure you use a good 3D FEM program that also includes a decent reinforced concrete design and analysis module to get it all right, okay???? It'll cost you a good amount to procure and license.

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Good morning, CaptMoosie, thx for your note.

Apparantly someone wants to build one. The school district in Overgaard & Payson each built one.

My job will be to design it. Material, size, placement of rebar, concrete, shotcrete, grouting, wall, ring beam, dome. My guess is they're going to use the MDI process (Monolithic Dome Institute). BTW, does shotcrete come in different strengths, f'c, like 4000 psi, or does one suffer a degradation due to the fluidity of the material? I would think the Binisystem is much more expensive.

I'm not familiar with the Natgun process. Do they weld the rebar prior to grouting the segments?

Since the arc of 1/2 the dome is almost flat because of the huge radius, I tried using the formula for a simply supported reinforced beam per p42 of Reinforced Concrete Design, Spiegel, 4th ed., but as expected, it came out negative for no matter how much steel or how thick the concrete was.

I am going to try to apply Roark's formula 1b, Table 9.3, p336, Circular Arches, 7th ed., but its not for a composite beam, so to what advantage?

Per your advice, I'm going to investigate an FEA software solution. Thx again.

Use an engineer from Monolithic. Videos by Monolithic: Good academic videos, with information from Monolithic. I like, some of the conceptual designs, especially the church and other public buildings. http://www.youtube.com/watch?v=2yJfcnIFYqg&NR=1 http://www.monolithic.com/topics/homes

Hope this helps, Adam Darriau

Good morning CR4radarriau. Thx for responding. I was interested in becoming the design engineer. I wonder if Monolithic's 5-day course will teach you this, or is it more for how to build it after you receive the plans. I will contact them next week.

Hello Highflying,

Wow, lots of questions to answer!

The reinforcing steel extending out from the edges of the precast concrete dome segments are mechanically anchored to the rebar from the adjoining segments.....rebar lengths extending out of the segment as per design to provide proper lap length.

I see you're using the late Doc Len Spiegal's & George Limbrunner's (of Hudson Valley Community College in Troy, NY) textbook! Great reinforced concrete textbook!!!! I received my AAS Civil Eng, Tech. degree there and had both Professors for several classes some 30+ years ago. Both were tremendous influences on me and my education...both wonderful men and human beings! Too bad that Doc Spiegal has passed away some time ago, not long after he retired from teaching. Truly sad.

Ummm, I wouldn't be using the beam formulas from Spiegel's textbook to design a dome structure because they don't apply.....a dome usually has an elliptical or spherical curvature and isn't level like beam. Domes are classified under "Thin Shells" just like barrel vaults ,etc.

May I suggest the following textbook for you to begin your study of dome design: "Structural Engineering Handbook", by Gaylord & Gaylord, McGraw-Hill Publishers, 1968. Refer to Chapter 20. Beware that the theory of domes is not for the faint hearted and is very involved. Once you understand the fundamentals of dome analysis and design, then you should have any problems working a high-grade FEA program designing the dome. You can find the aforementioned text used or new in either Ebay or Amazon for a decent price. there are several other reinforced concrete textbooks that may be of help to you like Wang and Solomon's wonderful text. It's pretty involved but worth every penny buying it!

You can specify any compressive strength you want as long as you can afford it or it's feasible for the ready-mix company to batch it.

Ummm are you sure you're up to analyzing and designing this structure, especially since it appears to me that you're a little unsure about the dome design?

um mm Natgun is not a construction method. Natgun is a constructor of precast prestressed concrete water storage tanks. i believe they're either based in Boston MA or up in NH.

s

Good morning CaptMoosie.

Gotta keep you thinking. That's what CR4 is for, right? <g>

You mean a couple of 1/4" bolts and a clamp? I would think even with the degradation due to phase transformation, welding would be the better way to go.

You were fortunate to have known Mr. Spiegel. I love my RCD book.

Thx for the book referals.

I expect the owners to specify the type of dome design.

You may be aware of this structure here in Mesa, AZ. at Val Vista and Brown.

Monolithic Domes Attract Newcomers At Living Word Bible Church ...

Good morning lynlynch. Thx for the link.

Hello Flyinghigh,

You're very welcome. Glad that I have been able to help is some small manner.

Yes, I have been fortunate to have known Doc Spiegal. He was tremendous educator and very dedicated to the Civil Engineering discipline. When I was attending HVCC I got a very lucky break working for a small Albany NY consulting firm where one of the Principals also taught nighttime structural engineering courses. Of course Doc Spiegal was the CET Dept. Chair and would visit our office from time to time to discuss course stuff etc with my boss. Usually I'd be there at the office in the afternoon after school working.....and sometimes Doc and my boss would invite me into their talks about engineering in general. Man, I felt like I had the Tiger by the tail just being acknowledged at all!!!! *LOL* I was also fortunate to have Prof. Limbrunner for a couple of structural engineering course. Wow, was he ever an educator as well.....ex-US Navy SEABEE and a PE. He was also our ASCE Student Chapter Advise and help us in building a concrete racing canoe. Oh the stories I could tell you about our adventures going to several of the races and the camp-outs throughout the weekend.....lots of great eats and too much booze, which he surprisingly tolerated (well up to a point that is)! *LMAO*

If I am able to find a few more of my reinforced concrete textbooks that deal with concrete arches and domes (many at just boxed away for sake of room in the office), then I'll be getting in touch with you about the titles, authors and publishers. Also, somewhere in my archives here I have concrete design software on a DVD/CD that deals specifically with concrete dome design. I forget the exact title of it...as I have never had the opportunity to use it. Let's see if I can find it, okay?

Are you a pilot by chance? One of these days I would love to obtain my Private Pilot's License. It's been a dream of mine since I was a little kid. Well, maybe someday soon!

Good morning CaptMoosie.

You were lucky indeed. Experience like that for a young man is incomparable.

I hope you don't go to too much trouble, but if you happen to find some of the research material that would be great.

Yes, I am. I'm a late bloomer, only getting my certificate in 1990. You should go for it. I think a technological background is important. If my significant other ever agrees to fly back to her erstwhile home in New London, CT, I'll look you up.

Good Morning Flyinghigh,

Thanks for the complements! I try to endeavor as much as I can. I'm not as young as you think I am as I'll be turning 52 in June.

I do have my New York State Professional Engineer's License and Registration. I'm a late bloomer as well because of the US Army and Reserves, family, house, and advanced engineering studies/degrees (MS/MS Carnegie Mellon U.).....received it '95 some 13 years after receiving my double BS in Environmental/Structural Engineering in '83. The Army paid for much of it thank God since I was a Grenada Vet (2nd Btn./75th Reg. Rangers: Op Urgent Fury) and in the USAR. Resigned my Officer's Commission (Cpt., on Promotion List for Major) in late '91 after returning from the Gulf after DS/DS at X-wife's (aka Tex-Rex) insistance......after 14 total years served, and 6 to go for retirement, but she didn't want to hear about it, period. By now i could have made Full Bird Colonel If I had stuck with it serving in an Engineering Battalion, followed by stint with 98th Inf. Div. HQ in Rochester, NY. Oh well, them's the breaks......

Yes, if you're ever back to New London CT look me up! The drive isn't that bad from here......even Danbury CT is a 1-hour drive from here down the Taconic State Parkway, and then take I-84 East from Fishkill NY (major IBM territory there). We could meet somewhere mid-way for a nice lunch, eh????

Just curious, but you appear to be a CE???

I bet a private pilot too, given the moniker?

Good morning CaptMoosie.

You have an impressive resume. Too bad you weren't able to stay in the military, but we all have regrets.

Yes, if I ever get back there, I will certainly give you a call. That would be great to meet you.

By education, I have a BSME; but I have drifted into construction design, with an emphasis on structural aspects.

Good Afternoon flyinghigh,

Yes, let's get together and have lunch or dinner together when you're able to get beck this way. I hope you can bring your wife along too, and we can make it a foursome. First round of cocktails are on moi. That would be a nice!

That certainly is a change in venue for you from Mechanical to Structural. Not too many make that change. Interesting......

Where in AZ are you located? Mighty nice countryside out there, especially up north near the GC. If it wasn't so blasted hot out there in the summer I'd probably move to some location there or up in northern NM in the high country....just lovely country and totally different than upstate NY. Maybe when I retire eventually.....*LOL*

Good morning CaptMoosie.

Yes, I will bring Dini when I come; but I don't know when that'll be.

Necessity is the mother of invention.

I am in the northern mile-high country, Prescott area. I can no longer take the summer heat of Phoenix and the southern area. My projects have been scattered thru out the state. Tell me again, your location in NY? The local housing market pricing is very attractive to purchase!

Good Afternoon Flyinghigh,

Yes, by all means bring your wife and I'll bring mine, even if she's bleary eyed from working the Graveyard shift at work (she's a RN).

Okay, now I know where you're at! The Prescott area is very nice and COOLER!! *LOL* Good to know that the housing prices are affordable there when it comes time to retire (if ever). The Great Recession must have plummeted the real estate market in your area quite a bit, much like Phoenix, LV, and LA?

I'm located about 25 miles north of Poughkeepsie NY, along the eastern shore of the Hudson River. We actually live about 1 nm from the historic Rhinebeck Aerodrome, which is pretty kewl. As an avid aviation nut-case, I can get my daily jollies watching the old WWI fighters and bombers, as well as the Barnstormers, flying overhead. Now if they could only expand and start including WWII Warbirds, then my year would be made for sure! I was a longtime (21 years) and very active member of the now defunct National Warplane Museum that was originally located in Geneseo NY, south of Rochester. They moved to the Elmira area in the early 90's which killed off a very large and dedicated volunteer base following them southward, which coupled with 3 successive rotten turnouts at their Annual Wings of Eagle airshows due to very bad weather eventually killed the museum. It is too bad that it happened, but the Trustees were blind deaf and dumb about the objections to the museum moving.....even oblivious to a large majority of the membership voting against the move! Go figure, eh? I guess money talks (and the Trustees, many of them were loaded) .....having been a longtime member of the Airshow Planning Committee I got t meet some very distinguished visitors and Airshow Grand Marshall's over the years: Gen. Jimmy Doolittle, Former NASA Astronaut Frank Borman, Ret. BG Chuck Yeager, Ret. Cmdr, Randy Cunningham, amongst others including a whole lot of WWII/ Korea / Viet Nam pilots where some where actual fighter Aces. We even had USAF modern fighter aircraft on static display in our museum collection that augmented our WWII and Korean War A/C: F-15A, F-14D, A-4F and an A-10A for starters. Was a pretty neat museum w/ membership from around the world. Miss it!

ba/ael's answer rates a big GA from me!

Well going!!! APPLAUSE!!!!!

I didn't even know that some of these textbooks were even out there....am famliar w/ Timoshenko's text's for the most part, except the two that you named here!

Good morning ba/el.

Thx for your input. I have ordered the texts you suggested, along with the others from CaptMoosie.

A good book on the subject is Thin Shell Concrete Structures by David P. Billington.

Good morning kdelta. Thx for the reference.

flyinghigh,

I designed a couple of cylindrical water reservoirs with domed roof in the City of Edmonton over fifty years ago. Everything worked pretty well and the tanks are still standing today.

I designed a similar reservoir in the Town of Vegreville a few years later which resulted in a horrible accident during construction. The concrete was being placed from the periphery toward the center when the falsework collapsed, killing one worker and seriously injuring two others.

The engineers retained to investigate the collapse determined that there were not enough posts supporting the roof, so the spacing of posts was reduced by a factor of two, both circumferentially and radially. This resulted in a massive amount of timber inside the walls of the reservoir.

The reservoir was reconstructed with this recommendation and everything worked out okay, but I believe the real reason for the collapse was missed and was not corrected the second time.

When I examined the collapsed falsework, it seemed clear that the vertical posts which had been placed on circumferential lines at eight foot centers, collapsed in a torsional or screw failure. All of the posts buckled in a direction perpendicular to the radius of the tank at the location of the post.

Radial bracing and horizontal bracing between posts on circumferential lines had been provided. At first glance, it seemed like adequate bracing, but it was not! What was missing in the original falsework was diagonal bracing placed between posts on each circle of posts to prevent torsional rotation about a vertical axis.

Don't accept "We've done it this way a million times before". You must insist that the Contractor braces his falsework properly. This includes adequate bracing, both radially and circumferentially.

Good morning Bruce. I am thankful you shared your experience.

I presume the domed cylindrical tanks in Edmonton were of the reinforced concrete design? Did you use formulas for a domed or conical thin shell? Did they utilize posts thru out the interior, or no posts between the walls? What were their dimensions?

The design of the monolithic domes I am considering is quite different from the one in Vegreville, in that there will be no posts in mine. Google Monolithic Domes to see details. I am a true believer in bracing. My designs tend to be on the conservative side.

As a result of the collapse, were you sued, or did you have engineer's insurance; or how did that turn out?

Both reservoirs in Edmonton and the one in Vegreville were spherical domes. The domes had no support other than the cylindrical concrete walls which also served to retain water. The diameter was 200' in the Edmonton domes, a bit less in Vegreville.

The posts I mentioned were temporary. They were used to support the plywood form and wet concrete, then removed when the concrete had cured.

The collapse was a result of contractor's error. The engineering company I worked for was not sued as it was not responsible for falsework design. There was a coroner's inquest which recommended a number of changes in the way falsework should be designed, inspected and constructed.