Design of a T-beam - Reinforced Concrete with FRP Bars: Mechanics and Design - page 292

Deflection due to live loads only is

w
w

LPos

∆ : = ∆⋅ =0.248 in. ⋅

LL_Br SL_Br

SPos

The multiplier for time-dependent deflection at 5 years (ACI 318-11) is

ξ := 2

The reduction parameter, Equation (8-14b) of ACI 440.1R-06, is

λ := 0.60ξ = 1.2

Δ LT _ Br := Δ LL _ Br + λ·(Δ DL _ Br + 0.20·Δ LL_Br ) = 0.838 in long-term deflection

“OK” if
“Not good”otherwise

∆ ∆

LT_Br lim

Check_ ∆ :

=

LT_Br

Check_Δ LT_ Br = “OK”

Average effective moment of inertia [2]: The value of I e at midspan is
computed as follows according to the procedure defined by Bischoff [2] and
discussed in Chapter 4. The ratio between the cracking moment and the
applied moment is smaller than 1.0:

M
M

crPos

= 0.74

sPos

⋅

M
M

crPos

γ :1.720.72 = − =1.187

Bischoff2

sPos

I

cr2

4

I: = =10749 in ⋅

e2

2

⋅

M
M

I

crPos cr2

1 −γ ⋅ 1 −

Bischoff2

I

sPos g

The value of I e at the continuous end is taken equal to the gross moment
of inertia because the ratio between the cracking moment and the applied
moment is larger than 1.0:

M
M

crNeg

= 1.208

sNeg

I e3 := I g = 58799·in. 4

The average value of I e is

I e := 0.85·I e2 + 0.15·I e3 = 17956·in. 4