Any ME's out there?

[phantom309]

Re: Any ME\'s out there?

Villengineer-

Thanks for your correspondence on this. I appreciate your opinions.

FWIW, the last building I built was identical to the ones I looked at and the only change that I made was to use more trusses and place them a little closer together.

I've enjoyed the learning process I've gone through so far on this project, including this thread. I've bought and am reading some excellent references including this great book and have enjoyed trying to learn new things.

I want to take the time to have fun learning about and building this new building. I'll take the time to do it right.

That said, there is a little voice in me that says that I'm taking this a little too seriously (I tend towards obsessive/****). Perhaps my past experiences have not been shared by others thanks to building codes (some folks have them, I don't), but living where I do, I've had lots of experiences putting up storage sheds, cattle turnouts, hay barns, etc over the years.

In every case, those were planned on the back of an envelope, materials were bought, poles were planted in the ground, etc and the thing was put together. If it wiggled a little, a brace was added. Sizes of materials were arrived at by guestimate and past experience. When in doubt, upgrade to the next size of materials and all will be fine.

I heard one time that "Anybody can build a bridge that will stand up. But it takes an engineer to build one that will just barely stand up". I think that applies to your typical barn/shed/etc. When in doubt, overbuild. You'll spend more money on materials (something the pro's work to avoid), but the cost savings of DIY will pay for the materials and if you enjoy the work, great.

Without exception, all of the thrown together buildings that I've put up over the years have held up fine, including an all time record snow three years ago.

But I acknowledge that using metal trusses is a different world. Except for the barn two years ago, everything I built was a pole barn. I've not had a problem with any of them, but I have seen a couple members sag a little under a big load in the older buildings. I'm guessing that pole barn construction would tend to give more warning and fail more "gracefully" than a metal truss that might show no signs of fatigue and then fail catastrophically.

So I'll keep at the books. It's part of the fun of doing something new.

Mark

 

[AV8R62]

Re: Any ME\'s out there?

A little common sense goes along way
It is your building and only you know the risk you are comfortable with .
I have seen many home built trusses, some look like you could park a tank on them and others look like they could fall under their own weight but all of them worked as far as I know.
if you build one that is not strong enough you will probably know it before you build the second one and then you can ajust your design .
remember you are not building a Church, school or hospital
it is a barn.
enjoy your project

 

[slowzuki]

Re: Any ME\'s out there?

I'm a mechanical engineer as well and I say you should contact a structural guy or pick up some civil engineering text books.

You should be looking at buckling of compression members as well. Also, please read more on ulimate tensile strength vs yield strength of materials. Safety factors are applied to yield strength in this this of design.

It really isn't ethical for me to offer any numbers for your design.
Please talk to a structural engineer.
Ken

 

[Villengineer]

Re: Any ME\'s out there?

</font><font color="blue" class="small">( remember you are not building a Church, school or hospital
it is a barn )</font>
Why would it matter what kind of building it is? If it falls on you, chances are you're still dead. Buildings bigger than a small shed aren't the best project for the trial and error school of design.

 

[AV8R62]

Re: Any ME\'s out there?

chances are he will not buid something that will fall (common sense)

And if it does chances are no body will be in it.

 

[Villengineer]

Re: Any ME\'s out there?

Those are some awefully big assumptions to make. Especially when you make them for someone else's life. This exact reason is why most areas have building codes, including buildings such as barns.

 

[AV8R62]

Re: Any ME\'s out there?

Back to my original point it is not someone else's barn it is his barn.
building codes change almost daily if a house or barn is more than a few years old it is not built to the latest spec's
but we still use them

 

[yooperdave]

Re: Any ME\'s out there?

There are importance factors applied depending on occupancy.

Esential facilities such as hospitals have a higher importance factor than a agricultural building which has a lower factor.

If you value your life, or the lives of other humans which may occupy your building, you may wish to provide more structural capacity.

My personal pole barn has much more vertical and lateral load capacity than any of the neighbors - I feel that I am worth the extra expense /forums/images/graemlins/cool.gif.

Yooper Dave

 

[phantom309]

Re: Any ME\'s out there?

Here's an update. I phoned a local ME (structural) who runs a small one-man shop. We're going to get together this weekend.

He said that any analysis he does would take him a while because he uses graphical methods to evaluate the forces and reactions in the truss. I know just enough about the graphical methods to know that I wouldn't want to evaluate the forces in a clothes line that way. Ugh!

I asked if he'd ever seen any computer based tools made for this purpose and he said that he had not. When I asked if he'd like to, he said sure! So I'm pretty excited. I bet that his jaw will hit the floor when he watches how easy it is to set up a truss/frame, put various loads on it and test the loads individually and in combination. And the real beauty of using SW to do the analysis is that as soon as you see a trouble spot in the design, you quickly make a change, and run the numbers again. Very fun stuff.

If he's impressed, I'll volunteer to help get him set up with the 30 day eval of the product I'm using and walk him through the process of setting everything up, evaluating, etc. With a little luck, I'll be able to roll back his bill by my consulting with him!

I'll let you know how it goes.

Mark

 

[AV8R62]

Re: Any ME\'s out there?

phantom309

Are using Solid Works ?
I have been using it for about two years now and it is a very powerful tool and more fun than Autocad and Cadkey