Light FRP Strengthening of Poorly Detailed Reinforced Concrete Exterior Beam–Column Joints

Data Availability Statement

Acknowledgments

Notation

A_jh

joint horizontal area;

A_f,eq

equivalent FRP area on the joint panel;

b_b

beam width;

b_c

column width;

C_I.D.

numerical coefficient accounting for initial damage of the joint panel;

C_M.A.

numerical coefficient accounting for the presence of mechanical anchors;

E_cycle,i

energy dissipated in the ith cycle;

E_tot

total energy dissipation;

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

concrete cylindrical compressive strength;

f_y

yielding stress of steel reinforcement;

f_a = N/A_jh

axial stress in the joint panel;

h_b

beam height;

h_c

column height;

k_pp

peak-to-peak secant stiffness;

L_b

beam shear length (measured from column centerline);

L_c

column shear length (measured from beam centerline);

N

axial load on column;

n_l

number of CFRP layers on the joint panel;

n_s

number of sides of the joint panel strengthened in shear;

p_t,c

joint panel principal tensile stress;

p_t,f

contribution of the FRP strengthening to the joint panel principal tensile stress;

p_t,tot

total joint panel principal tensile stress;

T

total tensile force in beam internal bars;

t_f

thickness of dry fibers;

V_b

beam shear;

V_b,cr

equivalent beam shear at the joint first cracking;

V_b,flex

beam shear at the maximum flexural strength;

V_b,max

maximum recorded shear strength on the beam;

V_b,y

beam shear at the yielding of longitudinal reinforcement;

V_c

column shear;

${\overline{V}}_i$

beam load for the ith cycle averaged between the positive and negative loading directions;

V_jh,cr

joint shear strength at the first cracking;

$V_{\mathrm{jh}}^{\mathrm{dem}}$

joint shear demand;

γ_joint

joint shear strain;

Δ_b

imposed displacement at the beam end;

ΔE_tot

percentage relative differences with respect to the energy dissipation of the reference specimens;

${\overline{\mathrm{\Delta }}}_i$

beam tip displacement for the ith cycle averaged between the positive and negative loading directions;

ΔV_b

percentage relative differences with respect to the shear strength of the reference specimens;

ɛ_f,e

effective FRP strain on the joint panel;

ɛ_FRP

maximum recorded strains on the quadriaxial CFRP fabric in all directions;

ɛ_fu

ultimate fracture strain of the FRP system;

ɛ_max

maximum recorded strain in the first cycle of each drift level;

θ

arctan

(h_b/h_c)

inclination of the shear crack in the joint panel;

ν = N/(b_c × h_c)

normalized axial load;

ξ_eq,i

equivalent hysteretic damping for the ith cycle;

σ

standard deviation;

τ_jh

joint shear stress;

τ_jk,cr

joint shear stress at the first cracking; and

${\tau }_{\mathrm{jh}}^{\mathrm{dem}}$

joint shear stress demand.

References