Monotonic and Cyclic Axial Compressive Properties and Modeling of Basalt FRP-Retrofitted Predamaged Short Columns

Acknowledgments

Notation

D

diameter of the cylinder specimen;

d_c,c

damage evolution parameters of concrete;

E_co, E_c, E_c,d

initial elastic modulus of plain concrete, FRP-retrofitted concrete, and FRP-retrofitted predamaged concrete, respectively;

E_Secu

secant modulus of the unloading point;

E₂, E_2,d

second slope of the stress–strain curve of FRP-retrofitted undamaged concrete and predamaged concrete, respectively;

$f_{\mathrm{co}}^{\mathrm{\prime }},f_{\mathrm{cc}}^{\mathrm{\prime }},f_{\mathrm{cc},d}^{\mathrm{\prime }}$

compressive strength of plain concrete, FRP-retrofitted undamaged concrete, and FRP-retrofitted predamaged concrete, respectively;

f_frp

tensile strength of FRP laminates;

f_l

confining pressure provided by FRP;

f_new, f_r, f_re, f_un

stress corresponding to the intersection point, reloading point, return point, and unloading point, respectively;

f₀, f_0,d

Y-intercept of the linear second portion of the stress–strain curve of FRP-retrofitted undamaged concrete and predamaged concrete, respectively;

k, k_d

values of (ɛ_un − ɛ_pl) calculated from the test results of FRP-retrofitted undamaged concrete and predamaged concrete, respectively;

k_e

effective rupture strain coefficient of FRP;

k₁, k₂

fitting coefficients;

m, p

fitting coefficients;

n

shape parameter of the transition section of the stress–strain curve;

t_frp

thickness of one FRP layer;

ɛ_co, ɛ_cc, ɛ_cc,d

strain corresponding to $f_{\mathrm{co}}^{\mathrm{\prime }},f_{\mathrm{cc}}^{\mathrm{\prime }},\mathrm{and}{f}_{\mathrm{cc},d}^{\mathrm{\prime }}$, respectively;

ɛ_ef

FRP hoop rupture strain;

ɛ_new, ɛ_r, ɛ_re, ɛ_un

strain corresponding to the intersection point, reloading point, return point, and unloading point, respectively;

ɛ_pl, ɛ_pl,d

residual strain of FRP-retrofitted undamaged concrete and predamaged concrete, respectively;

ɛ_uf

ultimate strain of FRP laminate using tensile test;

ζ_d, α_d, β_d, γ_d

reduction coefficients of initial elastic modulus, compressive strength, ultimate strain, and intercept strength, respectively;

η_c

descending path parameter of the stress–strain curve of plain concrete; and

ξ_d

reduction coefficient for (ɛ_un − ɛ_pl).

References