[TheForge] moment of a beam

[xlch58 at swbell.net]

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.

Charles, output follows....


Archon Beam Design Program

Beam Data:
W18X35
AREA(in^2) = 10.3
D(in) = 17.7
Tw(in) = .3
Bf(in) = 6
Tf(in) = .425
Rt(in) = 1.49
Ix(in^4) = 510
Sx(in^3) = 57.6
Rx(in) = 7.04
Iy(in^4) = 15.3
Sy(in^3) = 5.12
Ry(in) = 1.22
Zx(in^3) = 66.5
Zy(in^3) = 8.06



Archon Beam Design Program

INPUT DATA

Beam Type = W18X50
Beam Classification = W

Total Length = 15.00(ft)
Unbraced Length = 15.00(ft)
Young's Modulus = 3.60E+07(psi)
Moment of Inertia = 800.0(in^4)
Section Modulus = 88.90(in^3)
Strong Axis Bending!
Both ends of the beam are Fixed.

LOADS

( 1) Point Load = 6.55E+04(lbs)
Located 7.500(ft) from the left side.

( 2) Level Unif. Load = 50.12(lbs/ft)
Starting 0(ft) from the left side.
Over a length of 15.00(ft).

OUTPUT

Max. Moment = -1.24E+05(ft-lbs)
Max. Shear = 3.31E+04(lbs)
Max Deflection = 0.0695(in)
Reaction R1 = 3.31E+04(lbs)
Reaction R2 = 3.31E+04(lbs)

CODE CHECK DATA, AISC (ASD) 9th Ed.

AXIAL STRESS = 0 ksi

BENDING STRESS = 16.70 ksi
ALLOWABLE BENDING STRESS = 16.71 ksi, PER (F1-6)

SHEAR STRESS = 5.184 ksi
ALLOWABLE SHEAR STRESS = 14.40 ksi, PER (F4-1)

CONCLUSION:

The member axial stress passes !
The member bending stress passes !
The member shear stress passes !
The member combined stress passes !
Member is treated as compact.