Strengthening of Columns for Confinement - Strengthening Design of Reinforced Concrete with FRP - page 182

f − f

cc c

E = (7. 51)

2

ε

cu

f
EE

2

c

ε= (7. 52)

t

−

c 2

7.3.2.2 Eccentric Model Based on Mander Equations
The ultimate eccentric or partially confined strength f cc is de termined from
Equation (7.47) and is paired with the correspon din g strain ε cc to construct a
Mander eccentric curve. The corresponding strain ε cc is given by

f
f

cc

ε=ε + − 15 1

(7. 53)

cc co

c

and the ultimate strain ε cu corresponding to a specific eccentricity will be deter-
mined from a linear function between the ultimate point of the fully confined con-
crete ( f cu , ε cu ) and the ultimate point of unconfined concrete f cu 0 , ε cu 0 = 0.003, as seen
in Figure 7.9.

1

E
E

r

sec

r

−
ε−

f f

cu cu 0

sec, u

ε=ε −+ r 1 E =

(7. 54)

c

cu cc sec, u

0.003

+ 1

cu

ε

cu

f´ cc
f cc

f´ c

f cu

ε co 0.003 ε cc ε cc ε cu ε cu

FIGURE 7.9 Eccentricity-based confined Mander model.