Page 151 - Civil Engineering Formulas

COLUMN FORMULAS 89

Nomenclature for formulas Eqs. (3.4) through (3.12):
Q allowable load, lb
P ultimate load, lb
A section area of column, sq in
L length of column, in
r least radium of gyration of column section, in
S u ultimate strength, psi
S y yield point or yield strength of material, psi
E modulus of elasticity of material, psi
m factor of safety
(L/r) critical slenderness ratio
For columns of cast iron that are hollow, round, with flat ends, used in
buildings:
Q L
12,000 60 (3.4)
A r
Q L
Max 10,000; max 100 (3.5)
A r
Q L
9000 40 (3.6)
A r
L
Max 70 (3.7)
r
Min diameter 6 in; min thickness 1/2 in

P L
34,000 88 (3.8)
A r
For structural aluminum columns with the following specifications:

6061 T6 6062 T6
s y 35,000
s u 38,000
E 10,000,000

used in nonwelded building structures in structural shapes or in fabricated form
with partial constraint:

L Q
10 19,000 (3.9)
r A
L Q L
10 67 20,400 135 (3.10)
r A r