Flexural Strengthening of Beams and Slabs - Strengthening Design of Reinforced Concrete with FRP - page 122

In the transverse direction, use temperature and shrinkage reinforcement:

A s = 360 mm /m

2

min

2

UseNo. 10 bars @ 250 mm (400 mm /m).

Check shear capacity.

wL un

V .15 = = 50.47 kN

u

2

V =− = Vwd 50.47 − 15.96 × 0.175 = 47.68 kN ud u u

V 47.68

0.85

ud

= = 56.1kN

φ

V

ud

V .17 = fbd = 0.1725 × 1000 × 175 = 148,750 N = 148.75 kN >> O.K. c c w

φ

Strengthening design:

17.884 kN/m 2 ww w u = 1.2 + =× +×= 1.6 1.25.571.6 7.0 DL LL

There is an advantage of load factors.
Strengthening limits:

w =× + 1.1 w 0.75 × =× + w 1.1 5.57 0.75 × 7.0

SL DL LL new

2 2

= 11.38 kN/m < 15.96 kN/m O.K.

since w = 7 kN/m

2

= 146 psf < 150 psf

LL new

Positive moment section:

No. 10 @ 150 mm
No. of bars/m =

1000
150 = bars/m
Area of reinforcement/m = 100 mm 2 × 6.67 = 667 mm 2 /m
667
1000

6.67

A
bd
f
f

s +

ρ= = = 0.00381

s

× 175

400
25

y

ω=ρ= × 0.00381 = 0.06095 s

c

M
fbd

n

2

R =ω−ω= 0.59 0.05876 =

2

c

2

M = 0.05876 × 25 × 1000 × 175 = 44988444.5N-mm/m n

M = 44.99 kN-m/m n

wL

2

17.884 × 5.5

2

un

M = = = 38.64 kN-m/m

u

14 14

φ=× M 0.9 44.99 = 40.5kN-m/m >= M 38.64 kN-m/m

n u