F. K. Kong MA, MSc, PhD, CEng, FICE, FIStructE, R. H. Evans CBE, DSc, D ès Sc, DTech, PhD, CEng, FICE, FIMechE, FIStructE (auth.)-Reinforced and Prestressed Concrete-Springer US (1987)

270 Eccentrically loaded columns and slender columns
h' = 500- 50= 450 mm
b' = 300 - 50 = 250 mm
Mx (300)(106) h' - (450) -
(667)(HP) N
~ = ( 1 ~~~t) = ( 480)(1cP) N
Hence Mxlh' > Mylb' and eqn (7.3-3) applies.
p in the equation is obtained from Table 7.3-1, noting that
N (2300)(10 3 )
/cubh = (40)(300)(500) = 0·38
Hence, from Table 7.3-1,
p = 0.55 by interpolation
From eqn (7.3-3),
(450)
= 300 + (0.55) (Z50) (120) = 419 kNm
Step 2 Design the reinforcement for (N, M~
N = 2300 kN (given)
M~ = 419 kNm (from Step 1)
N (2300)(10 3 ) 2
bh = (300)(500) = 15·3 N/mm
M (419)(106) 2
bh2 = (300)(500Z) = 5.59 N/mm
From column design chart (Fig. 7.3-1),
Ascfbh = 3.5%
3.5% of 300 mm by 500 mm = 5250 mm
Provide reinforcement as shown in Fig. 7.3-4.
rn
y
2-32mm
X-· ·-X 2-32mm
y
Fig. 7.3-4
+ 1-40mm
• 2-32mm +t-40mm