Analytical Model to Predict Dilation Behavior of FRP Confined Circular Concrete Columns Subjected to Axial Compressive Loading

Acknowledgments

Notation

A_eff

effectively confined concrete area;

A_g

entire concrete area;

c₁

nondimensional empirical coefficient;

c₂

nondimensional empirical coefficient;

c₃

nondimensional empirical coefficient;

c₄

nondimensional empirical coefficient;

D

diameter of circular column;

D^′

width of effective confinement area;

E_f

FRP modulus elasticity;

f_c

axial stress corresponding to ɛ_c;

f_f

FRP confining stress of full system;

f_l

FRP confinement pressure of full system;

f_l,i

confinement pressure at the mid-plane of FRP strips;

f_l,j

confinement pressure at the critical section;

f_c0

peak compressive stress of unconfined concrete;

$f_{cc}^{\mathrm{\prime }}$

peak compressive stress of confined concrete;

$f_f^{\mathrm{\prime }}$

FRP confining stress of partial system;

$f_l^{\mathrm{\prime }}$

effective confinement pressure;

K_e

confinement efficiency factor = k_ɛ × k_v;

k_v

reduction factor;

k_ɛ

reduction factor;

n_f

FRP layer number;

s_f

distance between FRP strips;

s′

clear distance between two adjacent steel stirrups;

t_f

FRP thickness;

V_con

volume of concrete;

V_FRP

volume of fibers;

v_s

secant Poisson's ratio;

v_s,0

initial Poisson's ratio of unconfined concrete;

v_s,max

maximum Poisson's ratio at the critical section;

v_s,u

ultimate Poisson's ratio;

$v_s^{\mathrm{\prime }}$

Poisson's ratio at the mid-plane of FRP strips;

$v_{s,max}^{\mathrm{\prime }}$

maximum Poisson's ratio at strip region;

w_f

FRP width;

ɛ_c

axial strain corresponding to σ_c;

ɛ_c,m

axial strain corresponding to v_s,max;

ɛ_c0

axial strain corresponding to f_c0;

ɛ_cc

axial strain corresponding to $f_{cc}^{\mathrm{\prime }}$;

ɛ_cu

ultimate axial strain;

ɛ_cu,c

ultimate axial strain at concrete crushing;

ɛ_cu,r

ultimate axial strain at FRP rupture;

ɛ_fu

ultimate FRP tensile strain;

ɛ_h,F

FRP hoop strain in full confinement;

ɛ_h,P

FRP hoop strain in partial confinement;

ɛ_h,rup

FRP hoop rupture strain;

ɛ_l,i

concrete expansion at the mid-plane of FRP strips;

ɛ_l,j

lateral concrete expansion at the critical section;

ɛ_v

volumetric strain;

ρ_K

FRP confinement stiffness index; and

v_t,eff

effective tangential Poisson's ratio.

References