25’ 4x4 Metal Post in concrete or base plate on concrete piers?

   / 25’ 4x4 Metal Post in concrete or base plate on concrete piers? #1  

piaffepony

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I’m having an end wall built on my 72’x 300’ clearspan fabric building. The end wall is going to be R-Panel to match my barn. It is dome shaped and 30’ tall in the center.

I’m on Texas black clay soil. I’ve had a handful of contractors come out to bid on my job and it seems like they each preferred a different foundation style... a giant footing wall across the whole 72’ front... concrete piers with base plates, or the metal posts set in the concrete like a normal fence post.

What do you guys think? I just want to make sure it’s done right...
 
   / 25’ 4x4 Metal Post in concrete or base plate on concrete piers? #2  
Mount the steel post on concrete piers with a base plate. That way if the post get damaged some how it can be replaced.
 
   / 25’ 4x4 Metal Post in concrete or base plate on concrete piers?
  • Thread Starter
#3  
Mount the steel post on concrete piers with a base plate. That way if the post get damaged some how it can be replaced.

That’s what I thinking.
 
   / 25’ 4x4 Metal Post in concrete or base plate on concrete piers? #4  
Base plates sounds much better. Setting up the steel posts, all perfectly vertical and at the right top height, before and during the pour will be harder and the concrete is more likely to crack radially around the posts if poured in place.

If you set J bolts you can easily adjust the posts later, as you go, and then grout the plates when done. You can use plywood temporary plates to align the J bolts during the pour. Or you could just drill holes later and build with anchor bolts, but that seems a little more temporary.
 
   / 25’ 4x4 Metal Post in concrete or base plate on concrete piers? #5  
It's easy to replace a post if it's in the ground, or mounted to a plate. Just cut and weld. I'm not familiar with Ft Worth area, but if it's like the black clay around Greenville, it's horrible stuff. More important then how you mount the pole is how deep you go to deal with how absorbent and expansive the soil is. I've seen power poles five feet in the ground twist all over because of the soil there, fences never last. Whatever the minimum depth for your footings, I would add a few feet to it. If I wanted a pole to remain straight, I would want it 8 to ten feed deep.

Soil moves things in the ground when it becomes saturated with moisture, and then freezes. It's the ice cube effect. Most people never realize it with it's frozen out, but then see the results after it thaws and what was once straight is now leaning.
 
   / 25’ 4x4 Metal Post in concrete or base plate on concrete piers? #6  
Re: 25 4x4 Metal Post in concrete or base plate on concrete piers?

... a giant footing wall across the whole 72 front... concrete piers with base plates, or the
metal posts set in the concrete like a normal fence post.

I have 2 structures on my property that I built with steel columns. My deck uses 4x4x3/16" steel columns as
long as 18' tall.

The most common way I have seen these installed is on piers or footings/slabs with square baseplates bolted
down. I did it a different way, which you prob can not do if you have to pay an engineer to do uplift calcs.

I poured piers, then wet-set rebar into them. After the piers were hard, I then set the columns over the bars
and grouted the columns to cover the bars. I welded a lip-bead inside the columns first. I was able to
fine-tune the placement with a hammer before grouting, to get them perfectly in line. This way I
avoided the labor of plates and bolts, and got a cleaner install.
 

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   / 25’ 4x4 Metal Post in concrete or base plate on concrete piers? #7  
I’m having an end wall built on my 72’x 300’ clearspan fabric building. The end wall is going to be R-Panel to match my barn. It is dome shaped and 30’ tall in the center.

I’m on Texas black clay soil. I’ve had a handful of contractors come out to bid on my job and it seems like they each preferred a different foundation style... a giant footing wall across the whole 72’ front... concrete piers with base plates, or the metal posts set in the concrete like a normal fence post.

What do you guys think? I just want to make sure it’s done right...

I'm a little unclear from your description. Are the posts holding the weight of any roof, or are they just holding the wall?

Foundations are highly location-specific. There are two factors. First is the bearing capacity of your soil. Second is the local environmental factors. Around here you have to have enough area to support snow loads, go deep enough to prevent frost heaving, and have uplift protection for hurricane-strength winds. Other areas might have earthquakes or other factors to deal with.

How the post is connected to the footing is nearly as important as the shape of the footing: how deep it is, how much bearing surface area it has, and how it's shaped to avoid uplift. If the posts are just holding the wall and not any roof you're not talking a lot of weight so the footings don't have to be very big, just big enough to stay put.
 
   / 25’ 4x4 Metal Post in concrete or base plate on concrete piers? #8  
Concrete pile with steel plate.

What kind of forces is the top of the steel post subjected to. Thinking of wind loading, flexing, and buckling issues.
 
   / 25’ 4x4 Metal Post in concrete or base plate on concrete piers?
  • Thread Starter
#9  
I'm a little unclear from your description. Are the posts holding the weight of any roof, or are they just holding the wall?

Foundations are highly location-specific. There are two factors. First is the bearing capacity of your soil. Second is the local environmental factors. Around here you have to have enough area to support snow loads, go deep enough to prevent frost heaving, and have uplift protection for hurricane-strength winds. Other areas might have earthquakes or other factors to deal with.

How the post is connected to the footing is nearly as important as the shape of the footing: how deep it is, how much bearing surface area it has, and how it's shaped to avoid uplift. If the posts are just holding the wall and not any roof you're not talking a lot of weight so the footings don't have to be very big, just big enough to stay put.

It’s just a large vertical metal wall that won’t bare any roof weight. The wall’s frame will be bolted to the main structure for more stability but it won’t really add much to weight to the load bearing requirements.

The drawing is what I’m having built.. the other picture is an example of what some one else did, but using wood to kind of give you a better idea..

IMG_1001.JPGIMG_1002.JPG
 
 
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