Design of a T-beam - Reinforced Concrete with FRP Bars: Mechanics and Design - page 283

Bending moment due to dead load plus 20% of live load is

w .20w
w

+

D LNeg

M: = M ⋅ = 82.3ftkip ⋅ ⋅

1_ creep s1

SNeg

Ratio of modulus of elasticity of bars to modulus of elasticity of con-
crete is
n f = 1.277
Ratio of depth of neutral axis to reinforcement depth, calculated per
Equation (8-12):

( )

2

k: = 2 ρ⋅ n +ρ ⋅ n ρ⋅ n = 0.189

1new

f1newf f1newf f1newf

The tensile stress in the FRP is

M

1_ creep

f : = =⋅ ksif1_

f1_creep

k

1new

Ad ⋅ ⋅ 1 −

f1newf1

3

( )

“OK” if f ≤ f f = 12.8ksi ⋅

f1_creep f_creep f_creep

Check_Creep1 : =

“Not good”otherwise

Check_Creep1 = “OK”

The strain distribution is shown next.

ε f1_creep = 0.00113

A f

d f1 = 26 in

k creep_R ε fu = 0.00225

Navier's equation is applicable because the maximum concrete stress is
smaller than 0.45 f ′c:

E c ·ε c_creepl = 1178·psi < 0.45f ′ c = 2700·psi