Flexural Strengthening of Beams and Slabs - Strengthening Design of Reinforced Concrete with FRP - page 137

300 mm

50 mm

2 φ 13

300 mm

400 mm

3 φ 13

50 mm

P/2 P/2

1100 mm 300 mm 1100 mm

1000 mm 1000 mm

2500 mm

Beam B3

FIGURE 5.23 Example 5.15 showing the beam section and profile tested by Arduini,
Tommaso, and Nanni (1997).

max

f
f

a f

f

max c b y

ρ= 0.85 −ρ

(5.98)

f s

d

fd fd

f =ε E

fd

(5.99)

fd f

In design problems, the statistically correlated linear equation may be used to
determine a quick initial value for ρ f by substituting f fd into Equation (5.86) to replace
f f . Furthermore, a single iteration may be needed to adjust ρ f to its final value by
invoking the force and moment equilibrium:

Example 5.15: Analysis

Arduini, Tommaso, and Nanni (1997) tested a series of beams strengthened with
CFRP sheets, one of which failed by sheet debonding (Beam B3). The beam
(Figure 5.23) had the following parameters:

A = 398 mm

2

E = 400 GPa

s f

2

f *

A = 265 mm f = 3000 MPa

s

f = 340 MPa b = 300 mm

y f

f = 30 MPa t = 0.17mm

c f

No.oflayers( )3 n =

M = 51.66 kN-m ( P = 93.93 kN)

n ,exp n

M = 126.69 kN-m ( P = 230.35 kN)

n ,exp n