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Anchoring a Billboard Frame in Concrete Columns

06/22/2010 7:07 AM

For reasons best known to him, the Head of my daughter's school wants to build a permanent framework of steel pipes, extending the full length of the school's street frontage, to which banners, streamers and billboards can be attached. Per a proposal submitted by a local architect, the uprights of this framework are to be embedded 50 centimeters into the tops of existing reinforced-concrete columns, with the steel pipes welded to the existing rebars in the columns before the cavity is re-filled with fresh concrete.

I hate this thing because it will be a permanent eyesore, getting worse as it rapidly rusts in our Tropical climate. But as the Head seems determined to have this built, I want to make sure it doesn't collapse and kill somebody on campus or on the street outside. Nobody has done any wind-load analysis of it, so I am working on that, but once I have numbers for the shear and bending moment at the point where the upright meets the RC column, I don't know how to determine whether the proposed construction will resist that moment. My background is aero - not civil - you see. The young architect who has bid the job is enthusiastic, but clearly does not have the engineering skill to do this, so if it gets done I'll have to do it or twist the school's arm to hire a CE to do it, which they probably won't do.

Given that my daughter could be standing next to this thing when it falls over, could somebody either explain to me the procedure, or direct me to a source for this information? I am extremely nervous about this project - strength, failure modes, bonding of old to new concrete are just some of the "issues" that I have. But if I want to stop it or fix it - especially if there's extra expenditure involved - I have to be able to show that the present plan is flawed.

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#1

Re: Anchoring a Billboard Frame in Concrete Columns

06/22/2010 7:13 AM

You have my sympathy, it sounds like a nightmare. Sorry I can't actually help, not my field.
Del

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#2

Re: Anchoring a Billboard Frame in Concrete Columns

06/22/2010 8:10 AM

This is obviously a bad idea. The first thing I would do would be to submit a possible alternative, possibly something with simple non-rusting, cheap, pvc pipe as anchor points and the use of thin nylon printed signage with grommets and bungie cords to get any messages out there. These would be easily removable and stored away in the event of stormy weather. The next thing I would do is get on the internet and find actual footage of what happens to similar structures in the event of a hurricane/typhoon, i.e-metal framed billboard signs. Download this footage and use it to create a presentation to illustrate your point, (a picture is worth a thousand words). It seems as if this monstrosity could also have the potential to attract lightning strikes, not something you want in front of a school. I think if you make your case in a calm and cohesive manner, they hopefully will rethink this idea. Hope this helps and good luck.

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#3

Re: Anchoring a Billboard Frame in Concrete Columns

06/22/2010 8:41 AM

Perhaps a better way to go is to suggest a solution that uses new technology, such as an LED sign board (bill board). The sign board can be controlled by a computer within the school office, it is much more adaptable to changes, it can display endless variety of messages, and doesn't require a person having to climb up on a ladder to change it. It could be smaller and less obtrusive, yet more effective. The company providing the sign board can advise on the best method of installation, if they don't do it themselves. Here are a few links I found, doing a quick search.

http://www.adaptivedisplays.com/

http://www.alibaba.com/product/ph107219494-106799996-101402089/LED_Indoor_Signages_Video_Board.html

http://www.manufacturers.com.tw/electronics/Led-Sign-Boards.html

As a cheap alternative to the LED board (and to the structure he wants to build), you could suggest a rear-projection display, where the projector is mounted behind a window in the front wall of the school. 3M makes an excellent rear-projection screen for use in outdoor displays. As with the suggestion above, the projector could be run by a computer in the school office. This screen would be much less massive than the one you describe.

http://multimedia.3m.com/mws/mediawebserver?mwsId=SSSSSu7zK1fslxtUmY_Unxmeev7qe17zHvTSevTSeSSSSSS--

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#4

Re: Anchoring a Billboard Frame in Concrete Columns

06/22/2010 8:48 AM

One more thought. One major problem here is that ego is clouding common sense. I think that it is very important not to be confrontational with the head of the school. Present him with possible alternatives and possible consequences that are based in fact, and step away. A big factor in you succeeding here, is if the head of the school is allowed to take credit for coming up with any viable alternatives after weighing the facts, which of course will be quietly brought forward by you. Best of luck! Let us know how it turns out.

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#5

Re: Anchoring a Billboard Frame in Concrete Columns

06/22/2010 10:54 AM

Sounds like a pig-sty waiting to collapse!

Where's the local Building Inspector/Code Enforcement Officer in all of this mess.....surely he/she would put an immediate stop to this project without a Licensed Professional Engineer/Structural Engineer doing the actual design and construction plans???

Don't you do the design and plans, because if this monster collapses and maims or kills someone or produces property damage, then you, the inexperienced young Architect, and the school master are all legally responsible. If convicted, you'll be fined and facing some serious time in prison.

Has anyone even done an analysis of the existing concrete columns to determine if they can support the existing school building structure plus the loads generated by this "billboard"? Load analysis should also include earthquake loading too.

Is this a publicly funded school, or is it a private school? If the local government is the prime funding source for this school, where's the input from the local school board? If privately funded, where's the board of directors' input? Surely, someone is in charge of the purse strings!

IMHO, I see danger lurking from every corner regarding this boondoggle. You have permission from me to print this out and present it to the School Master. He appears to me to be a dangerously errant person and had better choose a PE to do the work, not some kid (the Architect) who has zippo experience in structural design or analysis. As you can see my opinion of Architects doing structural work is none too high......I tend to view the typical Architect through haded sunglasses as nothing more than a "frustrated artist", usually high on their own Grandiose and ego who know how to use light and textures to obtain the desired appeal and public response: not many can seriously do the engineering, and the ones that try to bluff their way through is are twice as dangerous as a Quack Doctor or "Snake Oil Salesman". I'm taking through dealing with many many Architects for 33 years on the professional level, and I have found that a great deal of them are not worth the powder to blow them to hell or heaven. Enough said........I'm off my soap box for now! I know I'll catch hell from the AIA for this! LOL Let 'um come!!!!

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#7
In reply to #5

Re: Anchoring a Billboard Frame in Concrete Columns

06/22/2010 12:10 PM

He was posting from the Philippines, I don't think permits and building codes are a big deal there.

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#8
In reply to #5

Re: Anchoring a Billboard Frame in Concrete Columns

06/22/2010 8:06 PM

This is the Philippines, and enforcement is very lax. I have it on reliable authority that there is a building code, but I've never seen it, nor seen any evidence of its enforcement. It's probably just as well, as there are millions of marginal people who would be driven onto the street or into the mountains if any code were enforced.

The school is a private sectarian academy, part of the La Salle brothers system. The school is seeking the support of the parents' foundation (a PTA, more or less, but with a lot of clout because it has a substantial annual budget) in building this contraption. I am an officer of the parents' foundation, which is how I got mixed up in it.

I should have made it clear in my original post (but didn't). The columns in question belong to a boundary wall. They do not support any school building. The boundary wall is typical for this area: poured reinforced-concrete columns at intervals, with the space between them filled with hollow cinderblocks. The hollows of the cinderblocks are then filled in with poured concrete with a little reinforcing steel. I have no idea about the foundation. Some portions of the wall have a bond beam to connect the tops of the cinderblock sections and the columns. The architect plans to put a bond beam where there isn't one currently.

Good suggestion about documenting disasters, but it's important to realize that structures even ricketier than this one are commonly built here, and outside the typhoon zone may, by the grace of God, stand for years. Disasters to others, in other climes, won't be dissuasive in and of themselves. I have to show that this construction is inappropriate to this place, now. The best way to do that, in my opinion, is to bring up proven standards, and show that this thing doesn't meet them. That's why I was inquiring about analysis techniques for determining allowable base bending loads at the socket. I've got the CRSI manual, which has allowables for compression loads on pipe columns but nothing about bending or shear.

I know the kind of architect you mean - basically an abstract sculptor who expects people to live in his creations. I've met this architect, however and he is a solid, unpretentious citizen cognizant of his limitations and his responsibilities. He has provided for every structural reinforcement technique that he can think of in his plans, and encouraged me to provide him the wind load calculations, but I believe that he has not run any numbers himself.

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#11
In reply to #8

Re: Anchoring a Billboard Frame in Concrete Columns

06/22/2010 11:51 PM

Even if the pipe structure above the existing columns is adequate to carry wind load, the existing columns and foundation were not designed for that condition. It is highly improbable that they are adequate for the additional moment.

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#12
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Re: Anchoring a Billboard Frame in Concrete Columns

06/23/2010 7:53 AM

"Even if the pipe structure above the existing columns is adequate to carry wind load, the existing columns and foundation were not designed for that condition. It is highly improbable that they are adequate for the additional moment."

I agree, but I need to PROVE that.

Since I posted my question I found my copy of the Standard Handbook for Civil Engineers (second edition) and started rooting around. I found this in Chapter 15: "The overturning moments acting on the base of of the structure...are resisted by axial forces in vertical elements and footings." It sounds like there is NO allowable bending moment at the base - it has to be resolved into axial forces in frame members, which means backbraces of some kind. There is an existing two-level billboard support on part of the fenceline that is built just that way: main frame anchored in the wall, with a separate vertical frame behind that, with its own footings in the ground, and members connecting the two (no diagonals, unfortunately).

I think I'll try to find out who the engineer was who designed that frame; maybe we can get him involved in this expansion project and inject a dose of reality.

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#6

Re: Anchoring a Billboard Frame in Concrete Columns

06/22/2010 11:23 AM

A project of this sort would require a building permit in my location. The Building Inspection Department would not grant a permit without the seal of a professional engineer on the drawings.

In the interests of safety, demand it.

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#9
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Re: Anchoring a Billboard Frame in Concrete Columns

06/22/2010 11:21 PM

Daktronics.com

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#10

Re: Anchoring a Billboard Frame in Concrete Columns

06/22/2010 11:28 PM

I agreed to everyone's comments about the demand of professional involvement of the CE. Especially when you do not know if the existing walls or posts were designed to take the new loads, there are risks that involve so CE need to take part to minimise the risk. Also it would help if you can do some research on the web to find few accidents happened due to old walls and posts to support your claim, it reminded me the accident happened in Adelaide South Australia last year.

Good luck

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#13

Re: Anchoring a Billboard Frame in Concrete Columns

06/23/2010 9:32 AM

I think that if the school really wants to make something like this, then it should be a cone shape over the hole schools parking lot & buildings, this systems take the best of wind & solar power resource and the bottom is out of the weather covered useiable space, It's called RENEWABLE(THERMAL)=WIND POWER THE ENERGY POWER SOURCE.

Get the facts on structure and power output.

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#14

Re: Anchoring a Billboard Frame in Concrete Columns

06/23/2010 10:48 AM

I did not see any mention of maximum height for the proposed banner poles? In my house in NYC, USA, I rigged and used G.I. pipes (corrosion resistant) , 2 inches in diameter with a 12 Ft. clearance from the ground with a span of 15 feet between the 2 poles. The top end of the poles are held together via fabricated angular hangers where some anodized steel materials were mounted. Extending another 15 ft. on one side to complete my sliding door channel for a 15' X 12' G.I. sheet metal door. By the way my poles are anchored on the ground by concrete footing 6 ft. below grade and bracketed to adjacent 3 ft. concrete walls on each end. I've had this set up for the past 10 years now, been subjected to at least 3 major storms in the country without any maintenance problem except some channel grease lubrication. Now if you are planning to rig similar set up, although my vertical load is much heavier, I would advise to punch flap-able holes in your banner(s) to minimize any anticipated wind loading. Any twisting / bending moments issues relates only to free standing columns such as antenna towers or high tension power structures that are at least hundred of feet above grade. I don't think the intended application will even go beyond 20 feet in height, I could be wrong too?? If you are going to use bamboo poles instead, then it will be a different scenario!

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#15

Re: Anchoring a Billboard Frame in Concrete Columns

06/24/2010 8:03 AM

Folks, you did it. I conveyed the more pithy responses on this forum, as well as my own research, to the president of the parents' foundation (I'm only the Secretary). She will inform the Alumni liaison at the school, who apparently has been put in charge of this turkey, that the foundation won't touch it without the approval of a licensed civil engineer.

I think we're out of the woods. The CE will certainly not approve the plans as they are now, and anything that he does approve will be much more costly, hence unlikely to be funded.

Meanwhile, however, I've taken to bringing Sibylle to the back gate, so I won't be putting her in jeopardy if this thing does get built.

Thanks again, folks!

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#16
In reply to #15

Re: Anchoring a Billboard Frame in Concrete Columns

06/24/2010 8:32 AM

Excellent!

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#17

Re: Anchoring a Billboard Frame in Concrete Columns

06/25/2010 9:36 AM

Hi! Kumusta gusto kung tulungan ka sa CR4 forum tungkol sa problema mo bellboard para sa iyong skwelahan....Ang fiancee ko ay aeronotical engineer like you..pero maraming kaalaman sa ibat ibang klase ng engeneering tulad ng civil engineering. kung gusto mong tulungan kita ipadala mo ang bellboard sketch kasama ang dimension at ang iyong windload calculation at saka ang lugar na iyong pagtatayuan my fiance ay tutulungan ka na gawin ang plano libre kaya huwag kang mag alala... bago lang ang aming company kaya gagawin namin ang tulong saiyo ng libre... please contact us at our enquires@apexappliedexperience.co.uk with information and will be happy to get the details for your design within safety margins free of charge... look forward to hearing from you... maraming salamat... asahan ko ang iyong kasagutan... but just to inform, that my fiance is english and i am a filipina feel free to email us in englist or tagalog...

ARJ

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#18
In reply to #17

Re: Anchoring a Billboard Frame in Concrete Columns

06/25/2010 10:44 AM

I'm sorry - I'm a foreigner (American/French national) living here in the Philippines, and I'm afraid that I read neither Tagalog nor Visayan. The English fragments of your postsuggest that you are offering engineering services free of charge. That is indeed generous, and I will email you to learn the details.

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#19
In reply to #18

Re: Anchoring a Billboard Frame in Concrete Columns

06/25/2010 2:09 PM

Further to your response, apologises for my reply to your posting in tagalog, I genuinely thought you might be conversant with tagalog. You are correct, I would in deed prepare for you and the school the correct details you need to construct a fully safe and compliant with international standards design free of charge. I look forward to receiving your details as requested, and then I will return your design details in the form of drawings (pdf form if necessary), but please send me the size of the billboard, the calculations you have for the windloading (I assume you have good idea of what the local conditions are) and the height of the billboard. If you can supply me with a photograph of the position where the billboard is to be positioned or a description of the surrounding soil/area this will help enormously.

ARJ

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#20
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Re: Anchoring a Billboard Frame in Concrete Columns

07/17/2010 6:55 AM

His concerns are genuine and applaudable indeed. We are talking about a school where kids are around. No risks can be taken, he is right. Send me a copy too - let me verify this entire project - its risks and its mitigations.

Please remember, concrete with age gains more strength, however these bill boards pose Moments and component of uplift to the supporting structures. Concrete is not good in tension. Let me verify it too.

fareed.siddique123@gmail.com

THIS WILL BE NO COST VERIFICATION FOR THE SAKE OF THE KIDS.

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#21
In reply to #20

Re: Anchoring a Billboard Frame in Concrete Columns

07/17/2010 9:32 AM

Sir the system that I refer to is over the whole school like a complete structure itself standing on stilks like the eifile tower that is not only a bammer frame, but a renewable energy for the school with all the schools' play area out of the weather.

This system is made of lite weight materails and tubing, Less costly than all of the best of wind and solar together in1 structure, witha combinations of 8 naturals and 6 man made thermal transfure systems ofr all the power needed at the school.

Get the facts from me free to all whom really want to do something for the planets' envioment. kennynabb6@win.net ref renewable energy for spam filter.

I will send all whom request it a copy of the shared technologies known. NOT the structure designs or where the techs are placed in the structure, structure designs are not shared tech.

Thanks for your request.

Kenny Magers ENERGY RESEARCHER

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#22
In reply to #20

Re: Anchoring a Billboard Frame in Concrete Columns

07/18/2010 3:45 AM

"His concerns are genuine and applaudable indeed. We are talking about a school where kids are around. No risks can be taken, he is right. Send me a copy too - let me verify this entire project - its risks and its mitigations."

I am deeply touched by the generous offers of time and expertise that this inquiry has elicited; this forum has somehow managed to attract an extremely high standard of subscriber.

If La Salle Academy's benefactor in the UK is agreeable, I would be delighted to have you review the plans that he is even now preparing for our consideration. As I am only the beneficiary of this work, however, and not its author or owner, his consent is needed.

Again, many thanks for your offer of help.

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