Design of a two-way slab - Reinforced Concrete with FRP Bars: Mechanics and Design - page 316

Flexural strength computed per ACI 440.1R-06: The tensile stress
in the GFRP is computed per Equation (8-4c) when ρ f > ρ fb , or is f fu if
ρ f < ρ fb :

( )

2

E ⋅ε

+ 0.85

β⋅′
ρ

f

f cu 1c

E ⋅ε − 0.5E ⋅ ε if ρ≥ρ = 80 ksi(f=80ksi) ⋅

f cu f cu f fb fu

f:=

4 f

f

fotherwise

fu

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

“OK” if f ≤ f

f fu

CheckMaxStress : =

“Reducebar spacingorincreasebar size” otherwise

CheckMaxStress = “OK”

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

⋅

f f

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

f fb

′

c

a: =

f

ε
ε+ε

cu

β⋅ min(d,d) otherEquation (8-6c) of ACI440.1R-06

1 f1 f2

cu fu

a f = 0.916·in.

a

f

c:= =1.145 in ⋅ Neutralaxisdepth

f

β

The nominal moment capacity is

a
2

ft kip
ft

⋅

( )

f

m:=A ⋅ fmin d d − =19 ⋅

nACI f f f1 f2