Friend of mine wants to build a tower on top of a hanger. Hanger has to be a minimum of 45 wide to fit his airplane and he needs to put a relatively heavy tower in the center of the span.. (right over the hanger door opening)..
(wish Boss Hog wasn’t banned)
He can use steel or web trusses or even TGI’s of whatever thickness would provide him enough strength but I suspect the wind loading would be far in excess of anything spanning that distance. Before we get busy hiring a engineer to do the actaul calculation we’d like to know if you’ve ever seen anything similar?
Replies
Frenchy
I copied your post over at QT, he might catch a look at it.
POST
A Great Place for Information, Comraderie, and a Sucker Punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
kinda foolsih to go for the most difficult location (dead ctr). Ought to put it at one of the corners. Even once a way is figured to do it, it'll be the most expensie way.
what kind of tower? weights? use of the tower (human or just equipment)?
Yes the tower will have the potential to be manned and it needs to be another 30 feet in order to get the FAA acceptance (for sight line purposes). In addition there are size requirements so the result will be rather heavy.
It's understood this is a tough one, and all proper engineering will have to be done but we're trying to find workable solutions to a seemingly impossible problem and can't afford to waste any money chasing something that might not be doable.
My first thoughts were close spacing of web trusses "built-up" with plywood glued and nailed on either side. Effectively turning the truss into Box beams..
Edited 11/17/2008 3:46 pm ET by frenchy
Probably has to be steel, frenchy.
what are the requirements (FAA and others) that force the tower to be dead ctr of the hangar? It's hard to figure where 22.5' in either direction (L or R of the hangar) is intolerable if you already have space for airstrip and hangars.
centered on the open span = big $$$.
frenchy, I've made contact-you can converse with him HERE.A Great Place for Information, Comraderie, and a Sucker Punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
How tall is the tower? Before he gets too far with the design, he better check with the airport to see if they have any height restrictions on structures.
I'm assuming from your post that the hanger is not built yet . . . right? Why does the tower have to be situated right over the door?
Yes it needs to be located there in order to have a complete view of his little airport and the approaches to it. A combination of sight lines, and airport authorization. Plus meeting aviation regulations..
If he can do this he can upgrade his airport and get some federal funding to change the takeoff strip from grass to concrete. etc.. That allows him other benefits as well. Among them will be the ability to put a cross wind landing strip in. Something he's wanted to do for decades..
He could have put a tower there and achieved much of what he wanted but then he wouldn't have the required spacing for noise abatement etc..
It gets really complicated the more you look into the various factors and the only workable solution is a tower in that location..
If it's supposed to be directly over the center of the hangar door opening, how does he expect to gain access to the tower?
Honestly,I'm a bit perplexed by this whole scenario.
Almost all small airports in the U.S., even busy county airports with two or more runways, have no control tower. The pilots of arriving and departing aircraft announce their postion and intentions on a common frequency, called Unicom, for the benefit of each other.
Edited 11/17/2008 5:26 pm by Hudson Valley Carpenter
It's a sight lines issue. To qualify for federal funding certain requirements must be met and clear sitelines are one of those requirements.. I'm far from the expert on this. He's a friend who's let me fly his planes on occasion and we share several other interests.. but there is only a requirement that a tower be available not that it's manned). Access is already solved rather elegently if I must say so.
The reason for the location of the tower in that spot is the other hangers have 99 year leases and he only has that one spot for his hanger.. if he puts the tower there he can't have a place to park his plane because of a variety of issues.. (another words all the hanger sites are spoken for) If he puts the tower behind the hangers he'd have to go much hoigher to get the same sight lines and the cost of a seperate tower would make it all moot.
Access is already solved rather elegently if I must say so.
So your friend is William Shatner and he's going to say, "Beam me up Scotty".
Actually I built a hinged, counter weighted staircase for my hangar, to reach a loft I put in. It goes up and down with a few ounces of pressure. Two lengths of cable, a pair of pulleys and two, five gallon pails filled with just the right amount of sand.
We're building a hangar right now and the header is 40'5" piece of steel I-beam 24" tall and 55 lbs per lf. You could probably span a bigger span with a taller and heavier piece of steel but I'd watch the size of the footing under the jacks ours are 6x6 square tube on a 3x3x2 pier w/ 3 rebar each way and 3/4" J bolts and we are not carrying any point loads and our span is less. We also had a Geo-technical engineer run tests on the bearing soil. The header assembly cost us $4,500 alone. The door exerts about 3,000 lbs of horizontal load in the open position. Hiring a good engineer is mandatory, he'll need to calculate the weight of the tower etc. but I think it can be done. You may want to look into those T shaped concrete beams but I'm not sure what kind of wall you'd use to hold them up, maybe 12" ICF's.
Looks like an expensive tower. But if he's got a plane with a 45' wing span he's probably got the cash for the steel.
------------------
"You cannot work hard enough to make up for a sloppy estimate."
It's only a 38 foot wing span (Lake Buccaneer) but he needs clearance and we figured some return on the entrance would be a smart move. Hanger doors are made right here in Minnesota so that's not an issue. They do the engineering for you.. we know the walls will meet most load requirements usings 15" ICF's so we aren't too worried there. The trusses were the only real concern.. you've given us the confidence to move to the next step and seek an engineer..
We hadn't even considered concrete but since you brought it up they make bridges that span much greater distances holding up several semi's at once so heck yes it should be doable!
Thank you..
I think it's definately do-able. Should be a pretty fun project actually. Hope you have a good engineer, I'm blessed with a really good one who speaks english as well as math and is willing to collaborate in the creative process and consider cost along the way. Makes life a lot easier.
Be well
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"You cannot work hard enough to make up for a sloppy estimate."
Reduce the load in the center by building a suspension bridge. Most of the large concrete I beam bridge structures are supported by high tensile cable running in tubes inside the the concrete I beam.An x-ray view would show the cables looking just like the golden gate bridge.
I recently built a hangar with a 40 foot door. The vertical loads were easy to deal with triple 48 ft trusses at the big door gable end. The horizontal loads were more challenging (in my case about 10,000 lbs spread across the 40 span. I found the easiest and least expensive solution was a single bar joist laid flat (horizontally) at the top of the door and welded to the door header.Also, this hangar happens to have a roughly 8x8 cupola set on top, kinda like a control tower. Easy to handle with a couple extra trusses.
very nice!
I like a lot of the details and with your permision will be showing this to my friend. He'd intended to do a dryvit (stucco) exterior to the ICF's because he wanted cheap.. I can see how to do it with ceder shakes though for not much more money..
He wanted ICF's because of their 200MPH wind rating. Both his Pitts and the Lake were damaged in the storm. He wanted to be able to prevent that in the future.
I'm thinking steel bar joists at the point loads of the tower can do it. It will be an engineering challenge though.
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
What happened to Boss Hog?
to use the words of Dovetail, Boss told someone to masticate him and that didn't go over very well with the mods
Actually, I heard that it wasn't that, he said ( well, spelled, with an exclamation Pt. inlieu of an ''i" ) Bull excrata.Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations
They kill Prophets, for Profits.
you mean bull manure?
That'd cover it.Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations
They kill Prophets, for Profits.
He ran afowl of the censors and was booted off.
Sorry to hear about the Boss. Thought he always had a lot to offer. Don't suppose he could do some type of penitence. Like some Hail Marys or something. Maybe a little groveling. Since none of us is not perfect, I would like to suggest that we forgive and forget.
Frenchy, anything can be engineered.
Putting the tower in the middle will, as others have said, greatly complicate the issue, but is still an easy engineering problem to solve.
You should get the FAA requirements and go visit a structural engineer. The site line requirements might be easier to meet, and less expensive to build, with taller tower on the side, or a shed roof.
I think we need to find out what those concrete bridge beams can be bought for.. Frankly if they are strong enough to hold up a lot of semi's and such over much bigger spans they sure should be strong enough for this application..
That's one of the wonderful things about this site..
I hadn't even considered concrete beams untill they were mentioned here and then I recall seeing some used ones in a field.
Frenchy, you really need to spend a little on engineering.
The engineers job is to do what needs to be done for the minimum cost.
Sure precast concrete components will work. So will steel or glulam beams. Which one will be the best solution depends on local costs, your personal preferences, and the knowledge base/skill set available to execute the design. If I were designing it for here, glulams would be my first inclination, because we have a plane in town the makes glulams, and has the test equipment to certify them. Concrete would be my distant third choice, because neither of the local ready mix places have a certified mix design, or any break histories on certified test equipment that would let them get certified in a timely manner.
You start trying to guess and golly this, and you can easily run the cost to three or four times what a well designed structure would cost.
Well you've got the cart before the horse. Locally we do make such beams (I've sold them equipment) plus I happen to know where there are stored bridge beams that were removed to widen the freeway. I also know that when they were advertized by the state there were no bids for them. I made a call to a buddy who works for the state this morning and he says I can have whatever I want (he did ask me for a nominal fee to do the paperwork) but cautioned me that simply getting them was a tiny portion of the final costs.. It will require cranes to lift them, a lowboy semi to transport them and cranes at the other end to unload them and place them. PLus the real unknown expense was what it would cost to cut them to size.
Another words free was too expensive <grin>
My rough estimate of the costs involved caused me to look at another solution. So I called up the place that makes the prestressed beams and ran a what-if past them.. On the surface it looks like that will be the answer.
I've yet to look at reinforced web trusses but my gut tells me they will be more expensive. I also know a site that sells used steel roof trusses so that's one more place to check as well.
Another words long before I need an engineer I'll have it reduced to a simple equation. By my doing the leg work and making decisions along the way my friend can do a quick calculation to determine if he can afford this or not. Then if it's a go we hire and pay for an engineer..
good luck with engineering on used beams that have been compromised with salt and use over the years
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Piffin, the only reason those concrete beams were removed was to widen the freeway. not because they had deteriorated to any degree.. road decks deteriorate with the use of salt etc.. beams are protected from the ravages of weather and salt by the road decks..
But as I found out free was too expensive..
Edited 11/18/2008 10:22 am ET by frenchy
Yeah, right.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Just looked at a job on Cobbossee. Owners want us to give them a price first, don't want to pay for design. But they need a design in order to figure out the cost.
Sound familiar?
Yeah, but frenchy is telling the designers and engineers they are getting the cart in front of the horse. What do we know???;)
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Haven't you ever been with someone who wants to know costs but doesn't know what they want? Or what things cost? how much work do you want to do before you give them a bid only to find out that's wildly above their expectations?
frenchy, known qualities and quantities can be engineered and designed to. Unkoin one cannot.When you design something, youhave a set of priorities and a seet of options.Not everything makes it thru to the end.IUn certain items like used beams are a definite overdesign call. That means that just like you discovered that the cost of acquiring the used steel beams exceeds the savings, so too the design costs and construction costs to cover the liabilities will exceed the savings.So if you want to make first priority that I will have to use X material because it is free, I then must design to it, with likelihood of extra engineering, extra trim, extra headroom or height allowance making walls taller and using more materials, extra footing work, etc, etc, etc...Engineering - when a new product is specified, the engineer can look up the values in a book. With a used structural component, IF you can get an engineer to even look at using it, he will run his own numbers and overdesign to be safe. Just that time and the support construction would run you over in cost. We have a saying around here - "Only a wealthy man can afford a used window."
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Piffin,
Please! they weren't steel they were concrete) steel would not sit around and have no bids they at a minimum would have gone and been melted down for scrap..
As I said I couldn't afford free because of other costs involved..
However if those costs were cheaper I wouldn't have worried about any deterioration for the reasons I gave earlier the bridge deck protects the beams from weather and salt.. besides they would have been massively more than required.
I don't know what sort of load a brdge is engineered for but the one that failed recently here in Minnesota is a good example.. That bridge had undersized "steel" gussets and yet it recieved permission to be widened and have more than 200 tons of material plus all the rush hour traffic and construction equipment on it..
So the original plans with undersized gussets stood up to decades of use, 2 full lanes added and 200 tons of material plus traffic. it was all that construction equipment that did it in..
I think it would withstand a 30 foot tower! over a 45 foot span..
However since I did the research that's one area we don't have to pay someone else to look into.
I'll do the same for the other choices. Plus one of my contacts told me where there are some really massive glue lams stored looking for a buyer. Came out of a lumberyard torn down recently.
I see you & Piffin still are still hitting it off ;-)Just curious, in all the thread, I didn't see anything that indicated the tower really had to be dead center in the hanger....seems like maybe the "client" thinks it looks right that way?
The client will only begin to THINK when he realizes it will save him 20-30K to move it to a back corner. But he may never realize that if he is letting frenchy do his design and thinking for him.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I fought him hard on where things needed to be located. The back corner would have been much cheaper. Two walls and a post to hold up the other corner.. He wouldn't go along with the idea. He has a hanger there now (or had) and that's where he wanted his new hanger and he also wanted the tower on top.. I didn't think it could be done because of the loads involved.. that was the reason for the question in the first place..
This is a most amusing thread.
Much akin to a dog chasing it's tail.
I think I can say, and say with pride that we have some legislatures that bring higher prices than any in the world. - Mark Twain
What you are describing sound a lot like the '30's style hanger in the movie the Rocketeer - an unremarkable movie except for several buildings that have stuck in my mind because they were so stylish.
I find the comments about locating the tower so as to minimize structural costs at the expense of the design rather perplexing. BTers usually chide anyone who suggests PT decking rather than Ipe, and try and lay tile without a good 1 1/2" of underlayment, but for some reason good design needs justifying.
Put the tower where you decide it should go. It's quite doable, and then you won't spend he rest of your life explaining to everyone that although the hanger looks odd, at least you saved a couple of thousand on steel costs.
Edit: I see they re-made the movie recently. I meant the '80s one.
Edited 11/19/2008 11:20 am ET by fingersandtoes
then you won't spend he rest of your life explaining to everyone that although the hanger looks odd, at least you saved a couple of thousand on steel costs.
A couple thousand? Time to count those fingers and toes again. ;-)
What would look odd would be putting a tower where there's never been one, except in the movies.
Airport control towers are always either separate structures or they are built onto the side of a hangar. They're at least three stories off the ground and require internal stairs below, per fire code.
I've previously asked frenchy about accessing a tower which is built over a very wide doorway but, so far, he's only said that he has an elegant solution.
Edited 11/19/2008 11:38 am by Hudson Valley Carpenter
"accessing a tower which is built over a very wide doorway"
A retractable stripper's pole?
That'd be elegant.
A retractable stripper's pole?
And a Maxwellhouse parachute for emergency decents. "Good 'til the last drop".
I didn't relize how courious you were.. The elegant soltion is an interior stair going up to a walkway right behind the hanger door fold. We can seal off the hanger yet still allow people to access the tower at any and all time of the night or day..Plus the way I sketched it he doesn't lose any critical interior space..
Edited 11/19/2008 4:43 pm ET by frenchy
Edited 11/19/2008 4:43 pm ET by frenchy
That's what I expected, but it's more about common sense than elegance.
I'm really not as critical of this idea as it might appear from what I've said, wiseguy that I am, but I do think it would be smart to run your stairway/walkway concept past the powers that be, while you're in the pre-engineering stage.
I have some suspicions about whether or not it'll be allowed under the firecodes.
"Time to count those fingers and toes again. ;-)"
Do the bent ones still count as 1 or 1/2?
Frenchy, have you considered supporting the tower between a pair of parabolic glue-lams? I have no clue what they cost, but it would seem that they would carry loads directly to the ground and be great for wind loads in line with the arches; perpendicular loads would require special consideration of course.
The largest all-wood structures in the world IIRC, were the dirigible hangars at Moffet Field and MCAS El Toro in California. Still standing after 75 years.
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BruceT
I have not been around much lately. What happened to Bosshog?
Have a good day
Cliffy
censors gave him the boot.. Real pity because he's a decent guy even if our politics didn't agree.
Did you look at the link I posted-he's responded to your question?A Great Place for Information, Comraderie, and a Sucker Punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
Yes I did and I tried to respond to him but for some reason they don't like my e-mail address.
Would you please thank him for me?
Sure thing.
Email me a reply and I'll post it over there for you.
Didn't like your email address? no kidding.
Couldn't have been from your end could it?
Afterall, it only took you 3 yrs to post pics.
thanks!A Great Place for Information, Comraderie, and a Sucker Punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
Other than being a source for truss info and a long story about he and the ole lady splitting I don't recall anything Political. I did see him on a post with a new handle the other day. It was like Bosshogtwo or something.
Have a good day.
Gotta go watch the Bruins kick the Leafs butt all over the ice!
Cliffy
>...I don't recall anything Political. <
that's the rub. While most of the polijivers were getting smashed they took out BossHog at the same time (Boss was expressing some frustration at the wrong time). Kind of like when you see fire ants attacking a butterfly. Stomping on them with your foot gets the ants... and the butterfly too.
I read an article in, I think it's the latest issue of 'Wired' magazine, about on line forums and blogs. They give some examples of popular on line communities where new owners have made what they considered 'minor' changes, and drove a lot of the regular users away, who then just started or joined competing forums.
Taunton should think carefully about the big picture when they decide to ban some of the very people who make this forum useful. Everyone can use a little spanking now and again, but banning shouldn't be done lightly. I have no idea what the real issue was, but I wonder if it won't hurt this forum a whole lot more than the mods might think. If you're going to provide the Tavern, you'd best be prepared to allow the sorts of behavior that it fosters. Otherwise, why bother to have it by invite only?
Sorry for the derail.
Frenchy - what sort of screws is he going to use on his tower?
Frenchy - what sort of screws is he going to use on his tower?
More importantly, what kind of finish:-)
It's absolutely possible with steel.
We built a church last year that has a 50' steeple in the middle of a 100' span. Of course, the load of the steeple may not be comparable to the load of the tower, but the wind load will be comparable, I think.
Regardless, as long as you don't specify that the beam can only be 12" deep or something like that, it can be done.
May be expensive.
Jon Blakemore
RappahannockINC.com Fredericksburg, VA
Quite feasible in Steel or concrete, but it will cost a couple bucks. You might even be able to do it in wood, but the truss depth will increase quite a bit and in the end wood may not be a great solution. Centering the tower not only will add the load at the worst point, but if one wants to support the tower with the roof also, the eng will need to very carefully consider the behaviour of the roof structure when fully loaded or partially loaded to make sure the tower doesnt sway too much when the roof flexes. One could probably build a steel portal frame assembly to support the tower and build the roof so it does not support the roof. This would allow you to use wood for the roof and a steel frame to support the tower. It will be a balance requiring a 3D structural analysis.
If the hanger is all new construction, could you build the tower legs into the walls somehow? Maybe a silly idea if the tower is not that tall, but ya never know.
Good luck
There ya go - build a steel A frame, 45 ft wide at the base, 30 some ft high, use that as the structural support for the tower, and build the hangar normally underneath it.
Steel is a consideration as is wood and concrete. He's not married to any one material or technique. Cost is the restriction. He has the existing hanger which winds destroyed recently and he will get some money from the insurance settlement. In addition he has some of his own funds but no real source for future income other than maintinance. So we're going to be looking into options and costs once we get some serious numbers from the engineers..
It's possible we will consider bracing to the outer walls but we know we don't want the base any wider than needed because of the sail effect of the tower.. In fact one option I've already run past him is open area below with open stairs to reduce the wind effect. He doesn't like that idea because he wants the tower to serve a secondary purpose of a viewing site for his guests to watch him play with his Pitts special.
The idea of taking some bridge beams to do this has great appeal.. We think we know where there are some stored that were taken off bridges removed to widen local hiways
"Cost is the restriction. "For the life of me, I can't understand why he is looking for the least cost effective way to build a tower when cost is his main consideration, especially if the tower is mostly for showing off
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
and I'm still trying to figure how he's going to get FAA money for having a tower that's not required.
The FAA doesn't grant the money but you need to conform to their standards to get the grants is my understanding of the process. Most smaller airports are community funded and paid for by the community.. this is a private airport privately owned. The tower is a requirement for the upgrade to be eligable for the grants. (the last sentence is my best take on what's required)..
I found this:
http://www.toolbase.org/PDF/DesignGuides/flitchplate.pdf
on google. Perhaps Frenchy can do his own engineering with this information?
And if he's nice to Junkhound or someone else that knows, they could give him the numbers for the 45' span?
A vigorous reply to the email I posted to the trussmaster can be found HERE.A Great Place for Information, Comraderie, and a Sucker Punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
What would the other dimension of the building be?
It may be better to span the longer way and keep that door in the gable end, especially if he's going with a bifold door. Those are a beast themselves.
I'm thinking 60ft-ish attic truss (12' room) and build the tower on top of that. Somewhere around a 12ft x 12ft tower?
Edited 11/17/2008 9:25 pm by MiCrazy