Seismic Behavior of Strengthened RC Columns under Combined Loadings

Acknowledgments

Notation

A_s

cross-sectional area of the tension reinforcement;

b, h, and h₀

width, height, and effective height of the section;

f_c and $f_{cmax}^{\mathrm{\prime }}$

axial and the maximum compressive stress of concrete;

f_y

yield strength of the longitudinal steel bars;

E

experimental and theoretical data of the specimens;

E_s, E_c

the elastic modulus of the reinforcement and concrete;

K_pj

average stiffness at the jth stage loading;

l

height of the column from the horizontal loading point to the column base;

M_y

yield moment;

n

number of cycles;

n₀

axial compression ratio;

P_y, P_u, P_cu

yield, peak, and ultimate shear force;

P_Ey,s, P_Eu,s

yield load and peak load of the experimental data for the strengthened specimens;

P_Ty,n, P_Tu,n

yield load and peak load of the theoretical data for the nonstrengthened specimens;

P_Ey,t, P_Eu,t

yield load and peak load experimental data of the CBST strengthened specimens;

P_Ty,0, P_Tu,0

yield load and peak load experimental data of the CBS strengthened specimens;

P_y,u, P_u,u

yield load and peak load of the uniaxial strengthened specimens;

P_y,b, P_u,b

yield load and peak load of the biaxial strengthened specimens;

P_Ed,s, P_Td,n

yield, peak and ultimate displacement experimental data of the strengthened and nonstrengthened specimens;

P_Ed,t, P_Td,0

yield displacement, peak displacement and failure displacement experimental data for the CBST displacement and theoretical data for CBS strengthened specimens;

R

error between the experimental and theoretical data of the specimens;

T

experimental and theoretical data of the specimens;

V_ji

peak loading corresponding to the ith cycle at the jth stage loading;

$u_{\mathrm{\Delta }}$

displacement ductility coefficient;

α

load reinforcement influence coefficient;

α_E

ratio of the elastic modulus of the reinforcement and concrete;

α_f

ratio of the yield strength of the longitudinal steel bars and the axial compressive strength;

α_w

correction coefficient of the stirrup characteristic data;

β

torsional load influence coefficient;

γ

displacement-strengthened influence coefficient;

δ₁

increase in the bearing capacity for the strengthened specimen compared with the corresponding control specimens;

δ₂

effect of the axial compression ratio;

η

height coefficient of the concrete compression zone;

η₁

effect of the loading method on the bearing capacity compared with the corresponding uniaxial CBS specimen;

η₂

increase in the bearing capacity under uniaxial and biaxial CBST loading conditions;

η₃

effect of the loading method on the bearing capacity compared with the corresponding biaxial CBS specimen;

λ_w

stirrup characteristic data;

μ_u, μ_cu

ductility coefficient corresponding to the peak displacement and the ultimate displacement;

ξ

displacement-strengthened influence coefficient;

ρ_t

tension steel ratio;

ρ_w

volume stirrup ratio;

Δ_b,t, Δ_b,0

yield, peak, and ultimate displacement of specimens under biaxial CBS and biaxial CBST;

Δ_ji

displacement corresponding to V_ji;

Δ_u,t, Δ_u,0

yield, peak, and ultimate displacement of specimens under uniaxial CBS and biaxial CBST;

Δ_y,t, Δ_u,0

yield displacement, peak displacement, and ultimate displacement of the theoretical data for the torsion-strengthened and nontorsion strengthened specimens; and

Δ_y, Δ_u, Δ_cu

yield, peak, and ultimate displacement.

References