Flexural Strengthening of Beams and Slabs - Strengthening Design of Reinforced Concrete with FRP - page 146

C t 1 in. (25.4 mm)

C b 1 in. (25.4 mm)

h s 10 in. (254 mm)

b ′ 13 in. (330.2 mm)

b s 4 in. (101.6 mm)

b f
b ´

C t

h f

4#3 #3 stirrups

@ 5 in. o.c.

h s

2#5

h w

C b

b s
b w

FIGURE 5.P.5

See Figure 5.P.5.

f = 4.9 ksi(33.5 MPa), f = 69.64 ksi(480.2 MPa), ε= 0

c y bi

t = 0.0065" (0.165 mm), E = 33, 000 ksi(227.5 GPa), f = 550 ksi(3792 MPa)

f f fu

Decker used VWRAP C100 CFRP for strengthening. Use the same material to
strengthen the beam to a 30% increase in the unstrengthened beam moment capacity.
Designate the failure mode involved. Assume no need to strengthen the beam in shear.

Problem 5.9
Repeat Problem 5.8 with a 60% strengthening ratio increase over the bare beam.
Designate the failure mode involved. Assume fire not to be a hazard in this case.
Also, assume no need to strengthen the beam in shear.

Problem 5.10
Design the slab given in Figure 5.P.6 based on ACI 318-11 code, and then strengthen
it based on ACI 440.2R-08, assuming no change in dead load. The slab is a two-span,
continuous solid, one-way slab with the following parameters:

w LL = 4.8 kN/m 2
w LL upgrade = 7.0 k N/m 2
f y = 414 M Pa
f c = 25 MPa
Slab thickness = 180 m m

Use NSM tape from Example 5.12 for negative moment region and CFRP sheets
from Example 5.15 for positive moment region.