Design of square footing for a single column - Reinforced Concrete with FRP Bars: Mechanics and Design - page 360

The stress-block factor, β 1 , is computed as indicated in Section 10.2.7 of
ACI 318-11:

0.85 if f ′ = 4000psi = 0.8

c

′

f
1000psi if 4000psi<f<8000psi

c

′

β= : 1.05 −⋅ 0.05

1

c

0.65 otherwise

10.3.2 Analytical approximations of concrete
compressive stress-strain
curve—Todeschini's model
The compressive strain at peak is

⋅ ′

1.71 f
E

c

ε= : = 0.0021

c0

c

The compressive stress at peak is

′

f
psi

c

σ= ": 0.9 ⋅

c

The stress-strain curve equation is

ε
ε

c

2" ⋅σ ⋅ c

()

c0

σε = " :

cc

2

ε
ε

c

1 +

c0

The concrete compressive stress-strain curve is

Concrete Compressive Stress-Strain Curve

4000

σ c (ε c )

2000

0

0 0.001 0.002 0.003

ε c

Strain, in./in.