How To Calculate Uplift - Building & Construction - DIY Chatroom Home Improvement Forum

 DIY Chatroom Home Improvement Forum how to calculate uplift

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04-11-2018, 02:37 PM   #1
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how to calculate uplift

This is a new problem for the same project I have been studying. Old posts entitled "how big can I go" and "wood purlins and steel trusses".
I want to attach treated 6x6 or 8x8 posts to concrete piers and have been introduced to a line of products made by Simpson Smart Tie. Lots of products to choose from, but need to know about what upforce or uplift I will be having to make a strong setting.
The roof will be about 24 feet wide and 62 feet long. The posts will be about 14 feet high.
How would I go about figuring what my forces will be?

04-11-2018, 08:44 PM   #2
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Re: how to calculate uplift

Not sure what you're asking, not that I could answer it. It sounds like you want to know what kind of metal connector you should be using. I think that is a wrong question because connectors are part of a structure, beginning with good enough anchor to the ground. Example, connector alone between the post and the roof is no good if the foundation comes apart. So this is something you should ask an engineer with all the local variables as well as kind of structure you want, and how much you're willing to spend. You have to look at the total of the structure, not just one part.
Example, search how building parts are strapped in florida. Even then, it starts with braced and reinforced structure that not only resists upward pressures but also racking movements. All these reinforcements are also basically trying to stop catastrophic collapse so people don't die, they are not for resisting all weather.

04-11-2018, 08:51 PM   #3
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Re: how to calculate uplift

This is engineer stuff, we just use the stuff we are told to. But for sure it is to be taken very seriously.

04-13-2018, 07:18 AM   #4
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Re: how to calculate uplift

Quote:
 Originally Posted by carpdad I think that is a wrong question because connectors are part of a structure, beginning with good enough anchor to the ground..
Carpdad, I agree completely with your logic. I have been working on this project for weeks now and not a single nail has been touched, not a single board has been purchased. And won't be until I have the whole thing figured out on paper.
I started with the roof, structure of the roof, size of the roof and worked down from there. The design has changed a dozen times, which I expected. The last thing I worked on was the posts and chose to use 6x6 for them. Now, I need to anchor the posts to the ground and have been introduced to a new term - Uplift. Didn't take too long before that made sense to me since with a good wind this will make an impressive sail. Lots of hardware from Simpson Strong Ties will be needed.
I have a number of options for the 6x6 posts to be anchored to cement and have chosen to use hardware that is installed while the cement is wet. I think this will be the strongest.
There are tables provided for me showing the capabillities of each piece of hardware and in the absence of my own numbers, I will chose the strongest available, even if it is overkill. A couple of hundred dollars here is well spent.
Next, I will have to determine what size footing these things will require to hold them. The cement pad calculators I have run across seem to be a little on the conservative size. I would rather have more cement in the ground. Cement is cheap.

04-13-2018, 12:54 PM   #5
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Re: how to calculate uplift

You can start your research here.

04-13-2018, 02:28 PM   #6
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Re: how to calculate uplift

Thanks ron45, found some really good lessons there.

Another problem just cropped up today - the standing seam roofing. Nobody around here rents crimpers, and there is no contractor locally who knows anything about it. I can buy an automatic crimper online for the price of a small car, or a cheap one that covers 7" at a time (yipee). Also, there is the style of seam to be considered. Apparently they are not all the same. I hope the one we have is not outdated.

04-14-2018, 06:43 AM   #7
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Re: how to calculate uplift

Metal connector can be any strength. But if connecting lumbers with the metals, lumbers may break at the connection points. Metals are braces only.

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