Strengthening of Columns for Confinement - Strengthening Design of Reinforced Concrete with FRP - page 213

Chapter Problems

Problem 7.1
For the rectangular column designed in Example 7.5 with 6 FRP plies for confine-
ment, plot the approximate confined interaction diagram and compare it to the plot of
Example 7.6 to show the improvement in behavior between the two cases.

Problem 7.2
One of the circular columns that were tested by Eid, Roy, and Paultre (2009) is inves-
tigated in this problem. The following are the properties of the column:

Diameter 11.9 in. 303 mm

Clear cover 1 in. 25 mm

7.35 k si 50.7 MPa

f c

n × t f 2 × 0.015 in. 2 × 0.381 mm

E f 11,30 6 ksi 78,000 MPa

ε fu 0.013 0.013

f yt 66.1 ksi 456 MPa

Hoop spacing 2.56 in. 65 mm

Hoop diameter #3 9.5 m m

Longitudinal bars 6 #5

6 ϕ 15.9 mm

f y 61.3 ksi 423 MPa

Plot the approximate confined interaction diagram. The experimental pure axial
compression point is at P n = 1250 kips. Note that this column is similar to that of
Example 7.1 except for different f c and spiral spacing.
Problem 7.3
One of the circular columns that were tested by Sheikh and Yau (2002) is investi-
gated in this problem. The following are the properties of the column:

Diameter 14 in. 355 mm

Clear cover 1 in. 25 mm

6.49 ksi 44.8 MPa

f c

n × t f 1 × 0.039 in. 1 × 0.99 mm

E f 10,871 ksi 75,000 MPa

0.013 0.013

ε fu

f yt 72.5 ksi 500 MPa

Hoop spacing 11.8 in. 300 mm

Hoop diameter #3 9.5 m m

Longitudinal bars 6 #8

6 ϕ 25.4 mm

f y 72.5 ksi 500 MPa