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cs
12-21-2011, 12:57 PM
I guess that maybe I'm a little over critical with all of my years in the construction industry. Here at the armory they had some of the guys build some columns for a new sign and I just don't think it will stand the test of time. I wasn't involved in the design or construction although I did convince them to get a pre-cast cap for it.

What we have is 2 signs and each sign has two columns to hold it up. It is basicaly 2 block & brick columns with the sign between them. I saw several things that to me didn't meet my standards.

First, like always, we will start at the bottom with the footings. The footing for the block is only 6" deep and the top of the footing is even with final grade with no re-bar in the footing. You may ask what is the problem with this and the problem that I see is that first the top of the footing is level with final grade. The top of the footing should be below the frost line. You may wonder so what, but the problem with this is the thaw freeze cycle could possible heave the footing out of the ground. The second problem I see with this is the footing is only 6" thick and while this should provide enough compressive strength I don't think that it is heavy enough to help with the wind load that the sign would be subjected to. The lack of rebar actually leads more to the next issue I see as we move up.

The next thing I saw was the lack of vertical rebar in the block units tying the block to the footings. If I would have been doing this sign I would have had a vertical bar coming out of the footings into the block at the corners and then would have had a vertical bar running up the height of the block and poured each cell solid. This ties the block into the footing making the transfer of the wind loads possible all the way to the footing. As it is now all you have a 3/8" mortor joint tying the block to the footing. They also didn't put any truss wire in the block, but this possible okay being as it is only a 2' x 2' x 8' pylon.

The next thing that I noticited is no weep wicks in the brick. Some may think that this is not important, but really it is. A weep wick is what gives any mositure that gets behind the brick a way out. If the moisture doesn't have a way out then your freeze/thaw cycle could start cracking brick and popping them out.

The next thing I noticted was the mounting bracket for the sign. What they used was a piece of flat steel with holes drilled in, which is fine, but what is not is the way it was mounted to the column. What they did was take this flat bracket and set it in a head joint on the brick. Now everybody knows that concrete (and mortor is just a weeker form of concrete) is great in compressin but sucks in tension. With the bracket just being set in a mortor joint the only think holding it in is the mortor and that is in tension not compression. Best case would have been to have a small steel post inside the block with the sign bracket attached to that and sticking out beyond the brick. In this case that may be the belt and suspenders approach, but you know you would have a good connection. The next best thing, and this is what I would have done, it take the bracket all the way back to the block where I would have poured a solid cell and used anchors to attach the bracket directly to the block.

The next thing I saw and was able to get them to fix was the way that they were capping the columns. They were planning on just capping it with brick. My problem with this is that you end up with a brick laid flat creating a flat surface with mortor joints. This would allow any moisture to set on top of the brick and work its way through the mortor joing getting moisture behind the brick and with no weep wicks to help the moisture escape and a good freeze you have more potential for failure. I managed to locate 4 pre-cast column caps which gives you a pitched solid surface and reduces the chances of water getting behind the brick.

So to recap, to shallow of footings not below the frost line, no vertical rods tying the block to the footing. No weep wicks to allow moisture to escape and sign brackets set in nothing but mortor.

Maybe I'm to critical, but I would never allow this to happen on one of my job sites. The sign may hold up forever, but then again the first hard freeze may heave the footings out of the ground. I guess only time will tell.

Chad

Paul Pless
12-21-2011, 01:16 PM
but then again the first hard freeze may heave the footings out of the ground.
ChadI'm looking forward to a soggy spring followed by high winds myself.:D

cs
12-21-2011, 01:26 PM
That will be intersting, that is if it makes it to spring.

Chad

Bobby of Tulsa
12-21-2011, 01:56 PM
Chad, have you ever erected signs? Ever see any of those eighty foot high rise Texaco signs?

cs
12-21-2011, 02:04 PM
Can't say that I erect the signs, i.e. I don't pour the footings or lay the block or any of that. That is what sub-contractors are for. I can say that I have been involved in the design and construction of many signs and I have studied concrete and steel design and statics and strengths of materials and I do understand about uplift and wind loads and proper construction techniques. Been doing this a long time now and I know what is required for pylon signs. And if you look at those eighty foot high Texaco signs you will probably see that they either have a great portion of the actual steel in the ground in conjuction with a massive footing with reinforceing bars.

I feel that I am more than qualified to critique the sign construction. Although I am not qualified to design the sign I have worked with engineers many a time on the design of very similar signs and I understand what is required.

Chad

Bobby of Tulsa
12-21-2011, 02:22 PM
I have worked in the sign business for a long time. Companies that do this don't stay in business if there signs fall down.

cs
12-21-2011, 02:26 PM
Being as you work in the industry you should see what I see with the mistakes in that sign's pylons. And while I have never designed a 80' high Texaco sign I would be willing to bet that they have a footing with enough mass to counter act the wind load or they have cantillivered the column out of the ground.

Chad

edited to add: the guys that built this sign are just standard Joes that work here at the armory and not a professional sign company.

Mrleft8
12-21-2011, 02:37 PM
Around here the footing would be 3' deep (To the top of the footing) with rebar or at very least a j bolt. The footing would be 33-50% bigger than the column it supported. So a 2' square column would have a 3' footing. Where a pair of columns are relatively close, a good contractor would pour one big footing pad to set both columns on. If the columns are going to be uncapped they should have weep holes at the base to keep moisture from collecting and cracking the masonry, but solid precast concrete, or flag stone caps would be better.
My suspicion is that those columns will fail. Not this spring, but probably by next spring.

cs
12-21-2011, 02:42 PM
Here we don't have to be 3' to the top of the footing. Our frost line is about 14". I would have had the top of the footings 16" below grade (2 courses of block) and it would have been 14" thick with #4's in the bottom with vertical #4's at the corners.

Chad

Mrleft8
12-21-2011, 02:46 PM
Actually..... Here the required depth is 30", not 3', but most decent contractors go the extra 6" because their grunts can't figure out what the little numbers on the yellow springy thingy mean.... ;)

P.I. Stazzer-Newt
12-21-2011, 03:14 PM
Over here we are moving away from solid signboard supports.

http://www.lattix.net/

BrianW
12-21-2011, 09:28 PM
Frost lines in Mississippi?

You know the ropes Chad. The sign only has to last until the next Change of Command.

The current officer will write in his OER... "had new sign installed, motivation levels reach highest point ever."

The next officer will write in his OER... "implemented base rejuvenation and beautification program. Tore down old sign, moral and efficiency reach new heights."

StevenBauer
12-21-2011, 10:20 PM
I think you're right about this sign, Chad. But it's the bottom of the footing that needs to be below the frost line, not the top. Around here the frost line is 48". And you can count on having a footing inspection.


Steven

Mrleft8
12-21-2011, 10:24 PM
I wonder if they've thought of doing "footing inspections" up in B.C......