Page 173 - Handbook of Civil Engineering Calculations, Second Edition

1.156 STRUCTURAL STEEL ENGINEERING AND DESIGN

Check minimum wall thickness of pipe, Fig. 45:

36 ksi
F y
t D 6.625 in. 0.083 in. (0.21 cm)
8E 8 × 29,000 ksi
t 0.280 in. > 0.083 in. o.k.
Check minimum cross-sectional area of steel pipe:
2
2
2
2
A s (R – R i ) (D – D i )
4

2
2
2
[(6.625 in.) – (6.065 in.) ] 5.6 sq.in. (36.1 cm )
4

2
2
2
2
A c R i D i (6.065 in.) 28.9 sq.in. (186.5 cm )
4 4
A s 5.6 sq.in
0.16 > 4% o.k.
A s + A c 5.6 sq.in + 28.9 sq.in
3. Analyze the selected column
In the absence of reinforcing bars:
A c
F my F y + c 2 f c
A s
A c
E m E + c 3 E c
A s

1.5
where E c w f c
, c 2 0.85, c 3 0.4.
The modulus of elasticity of the concrete
1.5
E c 145 3.5 3267 ksi
The modified yield stress for composite design is
28.9 sq.in.
F my 36 ksi + 0.85 3.5 ksi
5.6 sq.in.
51.4 ksi (354.1 MPa)

FIGURE 45