
C.) PLF
Pounds per lineal foot is used to describe loads on walls or long members such as beams. The beam receives an equal load for each foot of length.
Example: Beam 'A' has 2 sq ft of contributing load on each side (a tributary load). The load on each sq ft is 100 PSF. Therefore 2 ft + 2 ft = a tributary width of 4 ft x 100 PSF = 400 PLF along the beam.
Note: Rafters and floor joists have a tributary load equal to their spacing, i.e., 12" on center, 16" on center, etc. Their PLF = PSF x spacing in feet. To convert inches to feet, divide by 12. Example: 16 inches / 12 = 1.333 ft.
D.) UNIFORM LOAD
A uniform load is a continuous load along the entire length of a member and is expressed in PLF. A partial uniform load is also expressed in PLF, but does not run the entire length of the member.
Note: The ends of joists and rafters bearing on a wall or beam each produce a small point load and when spaced 24"oc or less (in a uniform manner) they can be considered to produce uniform loading.

