Design-Oriented Model of Unified Character to Determine Softening–Hardening Stress–Strain Behavior of FRP-Confined Concrete Columns of General Cross Section

Data Availability Statement

Acknowledgments

Notation

A_g

total area of a noncircular cross-sectional column;

b

column’s cross-sectional dimension;

d_eq

diameter of equivalent circular column;

E₂

slope of the linear second portion;

E_2,0

slope of the softening branch of unconfined concrete;

E_ctr

concrete modulus at the transition zone;

E_f

FRP modulus elasticity;

f_c

axial stress corresponding to ε_c;

f_c0

compressive strength of unconfined concrete;

f_ctr

stress at the transition zone;

f_ci

inflection stress;

f_cu

ultimate axial stress;

f_c,res

residual stress;

$f_c^{\mathrm{II}}$

axial stress at the second stage;

$f_c^{\mathrm{III}}$

axial stress at the third stage;

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

compressive strength of the standard cylinder;

f_l,tr,eq

FRP confinement pressure at the transition stage;

f_l,rup

confinement pressure at FRP rupture;

h

longer side of the section;

K_L

FRP confinement stiffness;

$K_L^{\ast }$

FRP confinement rigidity threshold;

k_eff

confinement efficiency factor;

L

column height;

n_f

number of FRP layers;

n_d1

degree of the polynomial function;

n_d2

degree of the parabolic function;

RI

confinement stiffness-based threshold;

R_r

corner radius ratio as 2 r/b;

R_sar

cross-sectional aspect ratio as h/b;

r

corner radius;

t_f

nominal thickness of an FRP layer;

α₁

polynomial coefficients;

α₂

polynomial coefficients;

α₃

polynomial coefficients;

α_b

calibration factor;

α_r

calibration factor;

α_sar

calibration factor;

η_ε

calibration factor;

η₁

calibration factor;

η₂

calibration factor;

λ₁

term considering stress loss beyond ε_ctr;

λ₂

term considering stress recovery portion;

ε_c

axial strain corresponding to f_c;

ε_c0

axial strain corresponding to f_c0;

ε_ci

axial strain at the inflection point;

ε_ci0

axial strain at the inflection point;

ε_ctr

strain at the transition zone;

ε_cu

ultimate axial strain;

ε_h,rup

rupture strain of FRP jacket;

ξ_1,r

calibration factor;

ξ_2,sar

calibration factor;

ξ_E,r

calibration factor;

ξ_E,sar

calibration factor;

ξ_r

calibration factor;

ξ_ε,r

calibration factor;

ξ_ε,sar

calibration factor;

ρ_K

FRP confinement stiffness index;

${\rho }_K^{\ast }$

confinement stiffness threshold;

ψ_f

reduction factor;

ψ_K

reduction factor; and

ψ_r

reduction factor.

References