Handbook of Civil Engineering Calculations

= 51.4 ksi (354. IMPa)

The modified modulus of elasticity for composite design is

Em = 29,000 ksi + 0.4 x 3267 ksi x

2

^

8

'

9

."f

5.6 irr

= 35,744 ksi (246,276 MPa)

The radius of gyration of a hollow circular shape

V#

2

+ Df

r = (See AISC LRFD Manual, p. 7-21.)

= V(6.625in)^+(6.065in)2=225.n(572cm)

for the bare steel pipe.

The modified radius of gyration for composite design

rm = r > 0.3D (the overall dimension)

= 2.25 in > (0.3 x 6.625 in = 1.99 in)

= 2.25 in (5.72 cm)

The slenderness parameter

A _ Kl [F^

^ VT V 3.

= 10.0 ft x 12 in/ft / 51.4 ksi

2.25 in x TT V^35 >^744 ksi

Because Ac< 1.5

Fcr = (0.65V^2 c)Fmy

= 0.658'^0 -^64 )^2 x 51.4 ksi = 43.2 ksi (297.6 MMPa)

The design compressive strength

4,Pn = Wf 0 ,

= 0.85 x 5.6 in^2 x 43.2 kips/in^2

= 205 kips > 200 kips required

(J)JPn = 205 kips (911.8 kN) for this case is also tabulated on p. 4-100 of the AISC LRFD
Manual)
The 6-in (15.2 cm) standard-weight concrete-filled pipe-column is satisfactory.

Related Calculations. This procedure is the work of Abraham J. Rokach,
MSCE, Associate Director of Education, American Institute of Steel Construction. SI val-
ues were prepared by the handbook editor.