Design of a T-beam - Reinforced Concrete with FRP Bars: Mechanics and Design - page 280

f f cannot exceed ff fu ; therefore, the following has to be checked:

( )

“OK” if f ≤ f f = 4ksi ⋅

f3 fu fu

CheckMaxStress3 : =

“Reducebar spacingorincreasebar size” therwise

CheckMaxStress3 = “OK”

The stress-block depth computed per Equation (8-4b) or Equation (8-6c)
depending on whether ρ f > ρ fb or ρ f < ρ fb , respectively, is

Af
0.85 f'

⋅

f3 f3

if ρ≥ρ Equation (8-4b) of ACI 440.1R-06

f3 fb3

⋅ ⋅ b

c w

a

: =

f3

ε
ε+ε

cu

β⋅ d therwiseEquation (8-6c) of ACI 440.1R-06

1 f3

cu

fu

a f3 = 5.188·in.

Neutral axis depth is

c: a

f3

= = 6.918 in.f3 ⋅

f3

β

1

The nominal moment capacity is

a
2

=⋅

f3

M: = Af d ⋅ ⋅ − 723 ft kip ⋅

nACI_3

f3 f3 f3

The concrete crushing failure mode is less brittle than the one due to
FRP rupture. The ϕ-factor is computed according to Equation (8-7) of ACI
440.1R-06:

0.55 if ρ≤ρ

f3 fb3

+ ⋅ ρ
ρ

φ

: =

f3

0.30 0.25 if ρ<ρ< 1.4 ⋅ρ = 0.65

bACI _3

fb3 f3 fb3

fb3

0.65 otherwise