[TheForge] moment of a beam

[xlch58 at swbell.net]

xlch58 at swbell.net wrote:

> Dave Mudge wrote:
>
>> Thanks Walter, This beam will be supported on each end by the
>> structure that it is incorporated into. Basically a  covering over the
>> front door of the machine shop where I work. The beam will hold a
>> trolley and chain fall. The length of the beam between supports is 15
>> feet. I am trying to find the load rating in the center of the 15
>> feet. How much weight can I lift in the center of this 15 foot beam.
>> It probably is A-36.
>> Thanks for your willingness to help.
>> dave m
>>
>
> Here is the output from a beam design program I have used.   I tried 
> multiple loading until I found the highest point load that passed 
> (65,500 lbs)..  Note that I had it calculate the max load with the 
> weight of the beam itself added in and assumed carbon steel.  I am not 
> a mechanical engineer, so take it as you will.  Also, I don't have my 
> AISC book near to hand to compare to.   I have limited space in my 
> office right now, and am spending most of my  time designing an 
> airplane and engine, so the AISC book is not used that often.   I 
> could not reconcile the  145,000lbs number Ken gave you.  I have to 
> assume this is for a distributed load, not a point load, as I got 
> close if I removed the weight of the beam itself and configured the 
> 145,000lbs load as a uniform load.
>
By the way, I also re ran it a couple of different ways.  moving the 
point load along the beam.  As expected the shear stresses increase and 
the bending reduces, but stays within the limits.  One big difference is 
wether the beam ends are fixed, pinned or free.   The original run was 
for fixed.  If you go with one of the other options, the limits are 
reduced.  If you you want any specific configuration run, let me know.  
Also let me know if you want the diagrams generated by the program.  
They don't add a alot, but I can send them to you pdf if you desire.

Charles