Axial Compressive Performance of Hybrid FRP–Concrete–Steel Double-Skin Tubular Columns with Varying Slenderness Ratios in Square-Circle Configuration

Data Availability Statement

Notation

A_cg

total cross-sectional area of the core concrete;

A_g

gross cross-sectional area;

A_s

total cross-sectional area of the steel tube;

A_st

total cross-sectional area of stiffeners;

B_o

outer-to-outer specimen width;

D_c

outer-to-outer depth of the concrete core;

D_e

deflection corresponding to the elastic axial load;

D_p

deflection corresponding to the peak axial load;

D_s

outer-to-outer diameter of the steel tube;

D_u

deflection corresponding to the ultimate axial load;

E_c

concrete modulus of elasticity;

E_s

steel modulus of elasticity;

E_sec

ratio of confined concrete stress to strain;

E_x

hoop directional elastic modulus of FRP;

E_y = E_z

transversely isotropic modulus of elasticity of FRP;

f

steel axial stress;

f_c

confined concrete axial stress;

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

modified unconfined compressive strength of concrete;

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

unconfined concrete compressive strength;

f_s

axial stress in the steel tube;

f_s,st

axial stress in the stiffeners;

f_y

yield stress for the steel tube;

f_y,st

yield stress for stiffeners;

f_uf

ultimate hoop-directional tensile strength of FRP;

G_x

hoop-directional shear modulus of FRP;

G_y = G_z

transverse isotropic shear modulus of FRP;

I_g

moment of inertia of the cross section;

K₀, K₁, and K₃

first, second, and third damage function constants in a microplane failure model, respectively;

L_eff

effective length of the specimen;

P_axial

average axial load;

P_e

axial elastic load;

P_e,NLFEA

finite-element-based elastic axial load;

P_p

peak axial load;

P_p,NLFEA

finite-element-based peak axial load;

P_u

ultimate axial load;

P_u,NLFEA

finite-element-based ultimate axial load;

r_g

radius of gyration of the gross cross section;

S₁, S₂, and S₃

proposed modification factors for confinement effect;

t_s

thickness of the steel tube;

α^mic

maximum damage parameter in the microplane failure model;

β^mic

factor for the rate of damage in the microplane failure model;

${\gamma }_0^{\mathrm{mic}}$

critical equivalent strain-energy density in the microplane failure model;

γ_c

reduction factor for $f_{co}^{\mathrm{\prime }}$;

r_m

a ratio based on the modulus of elasticity of unconfined and confined concrete;

μ_xy = μ_xz

transversely isotropic Poisson’s ratio for FRP; and

μ_yz

hoop-directional Poisson’s ratio for FRP.

References