Mechanical Behavior of Concrete Columns Confined with CFRP Grid-Reinforced Engineered Cementitious Composites

Acknowledgments

Notation

A_c

total cross-section area of column;

A_e

effective confinement area;

A_g

gross area with fillet radius (mm²);

D

diameter of column;

E_c

Young’s modulus of an unconfined cylinder;

E_f and E_m

secant modulus of the FRP grid and ECC, respectively;

E_f(ɛ_l)

secant modulus of the CFRP-ECC;

E₁, E₂, and E₃

tangent modulus of the CFRP-ECC in three stages, respectively;

R

radius of the cylinder;

b

width of the column;

f₀

intersection of E₂ extension line and the stress axial;

h

height of the column;

k

confinement effectiveness coefficient;

k_s1 and k_s2

shape factor of confinement coefficient for the prism;

m

shape parameter;

n_c

curvature control parameter;

r

the corner radius of the prism;

t_f

thickness of the CFRP-ECC;

ɛ_c

axial compressive strain;

${\epsilon }_{cc}^{\mathrm{\prime }}$

strain corresponding to peak axial compressive stress;

ɛ_cc,e and ɛ_cc,M

tested and predicted peak strain, respectively;

${\epsilon }_{co}^{\mathrm{\prime }}$

strain at peak stress of unconfined concrete;

ɛ_e

cracking strain of the CFRP-ECC; ɛ_e = 150 μɛ;

ɛ_f

ultimate strain of the FRP grid;

ɛ_l

lateral strain;

ɛ_ss

strain that begin to enter the strain hardening section, ɛ_ss = 0.001;

ɛ_t

strain of the CFRP-ECC;

ɛ_tu

ultimate strain of the CFRP-ECC;

ρ_m and ρ_f

cross-section area ratio of the FRP grid and ECC, respectively;

ρ_sc

longitudinal reinforcement ratio of prism;

σ_c

axial compressive stress;

${\sigma }_{cc}^{\mathrm{\prime }}$

peak axial compressive stress;

σ_cc,e and σ_cc,M

tested and predicted peak stress, respectively;

${\sigma }_{co}^{\mathrm{\prime }}$

compressive strength of unconfined concrete;

σ_cr

cracking stress of the CFRP-ECC;

σ_f(ɛ_l)

tensile stress of the CFRP-ECC;

σ_l

confinement stress; and

σ_tu

ultimate stress of the CFRP-ECC.

References