Handbook of Civil Engineering Calculations

Check minimum wall thickness of pipe, Fig. 45:

t > D -*- = 6.625 in /

36 ksi

f. = 0.083 in (0.21 cm)

V 8£ V^8 x 29,000 ksi v '

t = 0.280 in > 0.083 in o.k.

Check minimum cross-sectional area of steel pipe:

A 8 = <n(&-RD^(I?-Of)

= -^[(6.625 in)

2

• (6.065 in)
  2
  ] = 5.6 in
  2
  (36.1 cm
  2
  )

A 0 = TTfl

2

= -^A

2 =

T-

x

(

6

• 065 in
  )
  2 = 28
  
  
  • 9 in2
    O
    86
    
    
    • 5 cm2
      4 4 )
    
    
    
    
  
  
  
  

-V- ^.

5

;

6i

"

2

^ + ^^0.^2 = o.i6>4% O.k.

c 5.6 in

2

+ 28.9 in

2

3. Analyze the selected column
   In the absence of reinforcing bars:

Fmy = Fy +C 2 K^f-

AS

A 0

Em = E + c,Ec-j-

As

where E 0 = w^1 -^5 V^, C 2 = 0.85, C 3 = 0.4.
The modulus of elasticity of the concrete

£C=145L5 VI? = 3267 ksi

The modified yield stress for composite design is

Fmy = 36 ksi + 0.85 x 3.5 ksi x^28 '^9 ."f

FIGURE 45

outside diameter D

inside diameter Dr