Design of a T-beam - Reinforced Concrete with FRP Bars: Mechanics and Design - page 281

The design flexural strength equation is computed per Equation (8-1) of
ACI 440.1R-06:

ϕ bACI _ 3 ·M nACI _ 3 = 470·kip·ft

( )

“OK” if φ ⋅ MMM ≥ = 349 kipft ⋅ ⋅

bACI_3 nACI_3 u3 u3

Check_FlexureACI_3 : =

“Not good”otherwise

Check_FlexureACI_3 = “OK”

Tension lap splice: The recommended development length of FRP ten-
sion lap splices is 1.3 l d (Section 11.4 of ACI 440.1R-06). The minimum
recommended tension lap splice development length is

1.3 l d _ min = 41.861·in.

where l ld-min =32.2 in. as computed for the case of midspan.
The following minimum tension lap splice development length is consid-
ered and adopted:

l tls := 42 in.

Embedment length: Because this is a case of negative reinforcement, it
has to be checked if adequate moment capacity can be achieved at the end
of the embedment length. The maximum available length for embedment is
equal to half the length of the adjacent span.
In this case, a quarter of the adjacent span is considered.

l emb3 := 0. 25·1 2 = 90·in.

The developable tensile stress is calculated per Equation (11-3) of ACI
440.1R-06. Minimum between cover to bar center and half of the center-
to-center bar spacing is

+ φ , s

2

=⋅

f_bar f3

C:minc = 2in. c

b3

2

Bar location modification factor for top reinforcement is

α Neg3 := 1.5

Required stress in the FRP:

f ffr3 := E f ·ε f3 (c u3 ) = 49.191·ksi