Page 318 - Civil Engineering Formulas

252 CHAPTER TEN

E modulus of elasticity of material, psi
m factor of safety
(L/r) critical slenderness ratio

Q S y /m
(10.11)
A 0.75L mQ
1 0.25 sec 2r B EA

Suggested S 32,000; suggested m 1.7
y
P S y
(10.12)
A 0.75L P
1 0.25 sec 2 B EA

or
P 2 up to L
L
25,600 0.425 160 (10.13)
A r r
L
Q 1 2 up to L
15,000 140 (10.14)
A 4 r r
Q 18,750 for L
140 (10.15)
A 0.75L 1.76Q r
1 0.25 sec
2r B EA
When the column ends are pinned, the following formulas apply:
Q 1 2 up to L
L
15,000 140 (10.16)
A 3 r r
Q 18,750 for L
140 (10.17)
A 0.875L 1.76Q r
1 0.25 sec
2r B EA
P S y
(10.18)
A 0.85L P
1 0.25 sec
2r B EA
L
P 2 up to L
25,600 0.566 140 (10.19)
A r r
For structural silicon steel with S 80,000 psi and S 45,000 psi, using
y
u
structural shapes, or being fabricated with the ends riveted,
L
Q 2 up to L
20,000 0.46 130 (10.20)
A r r