Design of a column - Reinforced Concrete with FRP Bars: Mechanics and Design - page 343

The strength reduction factor is

ε
ε

f1

0.65 if 1.15 − ≤ 0.65

2

fu

ε
ε

φ :

f1

= 1.15 −

1

2

fu

ε
ε

f1
fu

0.75 if 1.15 − ≥ 0.75

2

φ= 0.75

1

The ACI compressive strength limitation is

ϕ 1 ·0.8·Pn1 = 1020·kip

9.5.2 Point 2—Neutral axis at the level
of the lowest section fibers
Neutral axis depth is

c 2 := h = 20·in.

ε cu = 0.003

c 2 = 20 in

Concrete compressive strain distribution is

ε

()

cu

ε x: = x

c2

c

2

The strain in FRP reinforcement is

ε ε

( ) ( ) () ()

cu cu

⋅ cdi if − ⋅ cdi − ≥−ε

2 f 2 f fu

c c

2 2

ε (i): =

f2

ε

( ) ()

cu

0if ⋅ cdi − ≥ 0

2 f

c

2