Design of a one-way slab - Reinforced Concrete with FRP Bars: Mechanics and Design - page 222

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

Af
0.85 f'

⋅

( )

f3 f3

c

b if

ρ≥ρ Equation 8-4b of ACI 440.1R-06

f3 fb3

⋅ ⋅

a: =

f3

ε
ε+ε

( )

cu

β⋅ d therwise Equation 8-6c of ACI 440.1R-06

1 f3

cu fu

a f3 = 0.986⋅in.

Neutral axis depth is

c: a

f3
1

= =⋅ 1.23 inf3 .

f3

β

The nominal moment capacity is

=⋅

a
2

f3

M: =⋅ Af d ⋅ − 17 ft kip ⋅

nACI _3 f3 f3 f3

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

0.55if ρ≤ρ

f3 fb3

+ ⋅ ρ
ρ

f3

φ : = 0.30 0.25 if ρ<ρ< 1.4 ⋅ρ = 0.55

bACI _3 fb3 f3 fb3

fb3

0.65otherwise

The design flexural strength equation is computed per Equation (8-1) of
ACI 440.1R-06:

ϕ bACI _ 3 ·M nACI _ 3 = 9·kip·ft

( )

“OK”if φ ⋅ MMM7kipft ≥ = ⋅ ⋅

bACI _3 nACI _3 u3 u3

Check _FlexureACI _3: =

“Not good”otherwise

Check_FlexureACI_3 = “OK”