Need help with Beam Calcs 2

[CajunNGnear]

Hey guys, log time reader, first time posting.

I have a 50' long beam with 5 supports on a 12.5' spacing. (0ft,12.5ft,25ft,37.5ft, and 50ft)

The beam has a uniform 500lb/ft load; 25,000 lbs total.

I'm trying to find the greatest moment force to find the stress in order to select the size of beam. My issue is determining the reation loads. I assummed 5,000 lbs on each of the 5 supports???? but I'm lost at finding the shear and moment forces (Haven't done this in 12 years) I've got my Roark's Eq book and I'm going through the Three-Moment Eg but I can't get the numbers to add up.

Is there a simpler method I'm missing???

HELP!

 

[desertfox]

Hi SWmechE

I Have uploaded a file with a calc on the original beam you posted ie a two span beam with 25000lb load on each span using the three moment equation.
When I compare this with the online calculator it doesn't line up, now I then checked equilibrum ie vertical forces should cancel and they do on my hand calc but they don't on the online calculator.
See what you think and let me know.

desertfox

 

[SWmechE]

Desertfox,

Sorry about the last file I posted, that was for the actual problem I was solving and not the question I actually checked the program against, I've attached my calculations using superpostion of the formula 28.

http://files.engineering.com/getfil...d08-4715-8519-1facd1a390a9&file=handcalc2.PDF

It appears that we are both getting the same answers (done two different ways no less) and it seems that there is a problem with the online program. Now that it appears that I wasn't just making errors in my calculations I'll post a bug to the website and hope it will get fixed.

Thanks for helping me check my sanity

 

[desertfox]

Hi SWmechE

Your welcome and another reason why computor programs should be questioned and not just believed.


desertfox

 

[Ron]

Hey guys..I checked it with two different FEA programs and the online program...they all come pretty close to each other. See my original reactions...they match closely to the two FEA's and the online program.

The only difference I got was a higher moment in sections 2 and 3 (beginning of section 2 and end of section 3). Moment was higher in the online program than either of the FEA analyses or the hand analysis using continuous beam approach.