Confining Stress Path-Based Compressive Strength Model of Axially Loaded FRP-Confined Columns

Acknowledgments

Notation

A

sectional area of FRP-confined concrete;

D

diameter of concrete core;

E_f

elastic modulus of FRP jacket;

E_c

elastic modulus of concrete;

f_ru

nominal ultimate lateral stress of FRP-confined concrete;

f_t

ultimate tensile strength of flat FRP coupon;

$f_c^{\mathrm{\prime }}$

compressive strength of unconfined concrete (150 mm × 300 mm cylinder);

f_c0

reported concrete strengths;

f_cu150

150 mm cube concrete strength;

f_{cc_pre}

predicted compressive strength of FRP-confined concrete;

f_{cc_exp}

measured compressive strength of FRP-confined concrete;

f_cc

compressive strength of FRP-confined concrete;

f_ac

compressive strength of actively confined concrete;

k_e

strain efficiency factor;

N

axial load of FRP-confined concrete;

S(P_i)

area enclosed by path P_i and its lower limit path P_i,low;

S(P_i,up)

area enclosed by path P_i,up and its lower limit path P_i,low;

SI

lateral stress dominant index;

t

FRP jacket thickness;

Δf(P_a, σ_ru)

increased strength of confined concrete under path P_a;

Δf(P_i, σ_ru)

increased strength of confined concrete under path P_i;

ɛ_fu

ultimate tensile strain of flat FRP coupon;

ɛ_m

volumetric strain of FRP-confined concrete;

ɛ_rc

lateral strain of FRP-confined concrete;

ɛ_rup

measured in situ rupture strain of FRP jacket;

ɛ_zc

axial strain of FRP-confined concrete;

ɛ_θc

hoop strain of FRP-confined concrete;

ɛ_θf

hoop strain of FRP jacket;

λ(P_i)

effect index;

υ_c

Poisson's ratio of concrete;

σ_rc

lateral stress of FRP-confined concrete;

σ_ru

ultimate lateral stress of confined concrete;

σ_zc

axial stress of FRP-confined concrete;

σ_θc

hoop stress of FRP-confined concrete; and

σ_θf

hoop stress of FRP jacket.

References