Design of a T-beam - Reinforced Concrete with FRP Bars: Mechanics and Design - page 260

()

ε c

f1 u1

0.65 if 1.15 − ≤ 0.65

2 ε

fu

()

ε c

f1 u1

φ

: 0.75 if 1.15 − ≥ 0.75

=

b1

2 ε

fu

()

ε c

f1 u1

1.15 − otherwise

2 ε

fu

φ= : .65

b1

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

ϕ b1 ∙M n1 = 267∙kip∙ft

“OK” if φ⋅ MM ≥ ( M φ = 267 kipf) ⋅ ⋅

b1 n1 u1 b1 n1

Check_Flexure1 :

=

“Not good”otherwise (M · = 145.44kip ft) ⋅ ⋅

b1

Check_Flexure1 = “OK”

Flexural strength computed per ACI 440.1R-06: The tensile stress in the
FRP 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 − 0.5Eif ⋅ε ρ≥ρ =64 ksi(f =64 ksi) ⋅ ⋅

ff :

f cu f cu f1 fb1 fu

=

4

f1

f1

f therwise

fu

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

“O K” if f f
“R educebar spacingorincreasebar size”otherwise

≤

f1 fu

CheckMaxStress1 :

=

CheckMaxStress1 = “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'

⋅

f1 f1

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

f1 fb1

⋅ ⋅ b

c w

a :

=

f1

ε
ε+ε

cu

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

1 f1

cu fu