Design of a T-beam - Reinforced Concrete with FRP Bars: Mechanics and Design - page 277

The following number of FRP bars is selected:

N bar3 := 10

A f3 := N bar3 ·A f _ bar = 7. 854 ·i 7.854·in.2 . 2

The corresponding FRP reinforcement ratio is (Equation 8-2 of ACI
440.1R):

A
bd

f3

ρ : = = 0.02158

f3

⋅

w f3

FRP bar spacing: The clear bar spacing is

bN − ⋅ φ−−

−

c in

eff bar3f_bar c

s : = = 5.722 in.f30_ ⋅

f30_clear

N1

bar3

The clear bar spacing is taken equal to

S f3 _ clear := 5 in.

The minimum required bar spacing is

S f _ f_min3 := mac(1·in, φ f _ bar ) = 1· in.

“OK” if s s
“Too many bars”otherwise

≥

f3_clear f_min3

Check_BarSpacing3 : =

Check_BarSpacing3 = “OK”

The center-to-center bar spacing is

S f3 := S f3 _ clear + φ f _ bar = 6 in.

Design flexural strength: The effective concrete compressive strain at
failure as a function of the neutral axis depth, x, is

ε

cu

yif ρ≥ρ

f3 fb3

x

( )

x,y :

ε = c3

ε

cu

dx xif

⋅ ρ<ρ

f3 fb3

−

f3