Design of a T-beam - Reinforced Concrete with FRP Bars: Mechanics and Design - page 274

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 = 0.55

fb2

+ ⋅ ρ
ρ

φ

: =

f2

bACI _2

0.30 0.25 if ρ<ρ< 1.4 ⋅ρ

fb2 f 2 fb2

fb2

0.65 otherwise

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

ϕ bACI _ 2 ·M nACI _ 2 = 443·kip·ft

( )

“OK” if φ ⋅ MMM ≥ = 271 kipft ⋅ ⋅

bACI_2 nACI_2 u2 u2

Check_FlexureACI_2 : =

“Not good” therwise

Check_FlexureACI_2 = “OK”
Development of positive moment reinforcement: The development length,
l d , for straight bars can be calculated using Equation (11-3) of ACI 440.1R-06:
Minimum between cover to bar center and half of the center-to-center
bar spacing is

+ φ , s , s

=⋅

f_bar f 21 f22

C:minc = 1.5in. c

b2

2 2 2

Bar location modification factor for bottom reinforcement is

α Pos := 1

The minimum development length is computed according to ACI 440.1R-06
Equation (11-6):

f
fpsi

fu

α⋅ − 340

Pos

′ ⋅

c

1: = φ= 32.201 in. ⋅

d_min

C

f_bar

b2

13.6 + φ

f_bar

The following development length is used and is available to develop the
required moment capacity:

l d := 33 in.