Design of a column - Reinforced Concrete with FRP Bars: Mechanics and Design - page 350

Development length and tension lap splice: The development length, ld,
for straight bars can be calculated using Equation (11-3) of ACI 440.1R-06.
The minimum between cover to bar center and half of the center-to-center
bar spacing is

+ φ , s

2

f_bar f

⋅

C:minc = =3 in

c

b2

2

The bar location modification factor is:

α Pos := 1.5
The minimum development length is computed according to ACI 440.1R-
06 Equation 11-6:

f
fpsi

fu

α⋅ − 340

Pos

′ ⋅

c

1: = φ = 52.4in.

d_min f_bar

C

b2
f_bar

13.6 + φ

The following development length is considered and adopted:
l d := 53 in.
The recommended development length of FRP tension 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 = 69 in.
A tension lap splice of 70 in. is considered and adopted.

9.6 STEP 4—DESIGN FRP SHEAR REINFORCEMENT

Preliminary calculations: The maximum shear acting on the column is

V u := max(V u1 , V u2 , V u3 , V u4 , V u5 , V u6 ) = 23∙kip

The ratio of the neutral axis depth to effective depth of the longitudinal
reinforcement can be calculated as follows:

( )

− A(i) if d(i) ≤ kd N1 ⋅ −

f f f f

A k, i) : =

f_e

( )

A(i) if d(i) ≥⋅ kd N1 −

f f f f

( )

2

( )

N1
f
∑

−

S(k) :b kd N1
2

⋅ −

E
E

( )

f f

( ) ( )

f

= ⋅ −⋅ A ,i ⋅ d(i) kd N1 ⋅ ⋅ −

o

f_e f f f

c

i=0