Large Concrete Columns Internally Reinforced with GFRP Spirals Subjected to Seismic Loads

Acknowledgments

Notation

A_c

cross-sectional area of the core to the center of transverse reinforcement;

A_g

gross cross-sectional area;

A_s

area of steel longitudinal bars;

A_sh

required area of the FRP lateral reinforcement within spacing s;

D_md

distance to the most damaged section from the stub–column interface;

d_b

nominal bar diameter;

E_f

modulus of elasticity of GFRP reinforcement;

E_s

modulus of elasticity of steel reinforcement;

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

maximum compressive concrete cylinder stress;

f_u

ultimate strength of reinforcement;

f_y

yield strength of steel reinforcement;

M

moment at the critical section;

M_max

experimental maximum flexural strength;

M_n

nominal moment capacity;

L

shear span of column;

P

axial load applied to the column specimens in the test setup;

P_o

nominal axial load capacity of the column at zero eccentricity;

P_L

applied lateral load;

P′

vertical axial load applied to the real-life column, which is always perpendicular to the foundation;

V

shear force at the column base;

V_max

maximum shear strength measured at the base of the column;

V_n

nominal shear capacity;

V′

applied shear force;

s

center-to-center spacing of transverse reinforcement;

Δ

tip displacement of the column;

Δ_u

ultimate deflection;

Δ_y

nominal yield deflection;

δ

lateral drift capacity of a column corresponding to 20% decay;

δ_PL

deflection at the point of application of lateral load;

ɛ_u

strain at bar rupture;

ɛ_y

strain at yield of steel reinforcement;

θ

inclination of the column–stub interface;

μ_Δ

displacement ductility factor;

μ_Φ

curvature ductility factor;

ρ_l

reinforcing ratio of longitudinal reinforcement;

ρ_h

volumetric transverse reinforcement ratio; and

Φ

curvature at the critical section.

References