Personal project

[Thebigmidget]

Howdy folks. I have a little personal project that I have put in the works and I needed a little advise on some weight issues for some steel work.

I'm going to be spanning 24 feet and I wanted to used steel angle to do it with... 4 x 4 x 1/2 angle... The load spread along the entire length of the angle is just 345 lbs from end to end with litte holes drilled every 24 inches. I'm worried that such a long span would create sag in the middle of the run which is not something I can have with what i'm designing.

What I needed to know is, would the weight of the angle and then the added weight of the load cause sag in the middle? Am I oversizing the angle or is it to small? If it would sag could I use U channel to solve this or am I SoL with trying to span 24 feet to begin with.

Just for more info .... I could deal with up to about 1/4 sag in the middle....Not much more though.

Thanks for any advise you guys could give me.
O'Michael

[Thebigmidget]

Ok, I'm trying to do this on my own with what is provided on the site but Im a little confused.. Does anyone know if this is the formula I need to use? http://www.engineersedge.com/beam_be...m_bending1.htm

[PinkertonD]

could I use U channel to solve this or am I SoL with trying to span 24 feet to begin with.

As reluctant as we are to help with any overhead supports, I can say this, that in order of effectiveness for a span of 24' angle would not be a good choice. It's weight to stiffness is very poor. Channel is better, but can be prone to rapid failure with twisting. For single entity beams (solid steel), an I-beam configuration is the most efficient in terms of weight for stiffness.

Having said that, a beam of that width, even though load is relatively light, should have some means of preventing it twisting. It would need only around 5-degrees of twist to begin rapidly failing, falling down and possibly killing someone.

You need to consider what the beam is attached to or resting on and how it is fixed to that. Designing a load carrying beam is not just a simple task of finding something that will not deflect (sag) in the middle. Is there any side load that would allow/provide for movement and thus rapid failure?

I strongly suggest you get an Engineer to design the entire thing for you. Sorry to be of so little help but the risks are too great for a DIY project.

[zeke]

Just for curiosity, what is the application. If you can show that failure would not result in human injury, well maybe with sufficient safety factors I would take a look.