Bond Performance of GFRP Bar-Splicing in Reinforced Concrete Beams

Acknowledgments

Notation

A_fb

area of cross section of one FRP rebar;

A_tr

area of transverse reinforcement in the lap zone;

C

minimum of the concrete cover up to the center of rebars and 50% of the spacing of the rebars;

C_E

environmental reduction factor;

D

damage curve parameter;

d_b

diameter of longitudinal rebars;

d_cs

smaller of the distance of center of the rebar from the closest concrete surface and two-third of the center-to-center spacing the bars being developed in mm;

E_f

elastic modulus of FRP rebars;

E_s

elastic modulus of steel;

E_t

elastic modulus of stirrups;

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

compressive strength of concrete;

f_bf

design bond strength of concrete;

f_cr

cracking strength of concrete in MPa;

f_f

rebar stress at the end of the embedded length (=C_E f_fr);

f_fr

required stress in FRP rebars;

f_fu

tensile strength of FRP rebars;

f_R

factor for rebar surface properties;

f_u

ultimate strength of rebars;

f_y

yield strength of rebars;

f_yv

yield stress of confining stirrups;

G_s

shear modulus of the bond-slip relationship;

h_dmg

damage curve parameter;

k

factor for the effect of non-contact lap;

k₁

rebar location factor (=1.3 for horizontal rebars placed such that more than 300 mm of fresh concrete is cast below the rebars; and 1.0 for other cases);

k₄

rebar surface factor (=ratio of the bond strength of the FRP rebar to that of a steel deformed rebar of the same cross-sectional area; =0.8 in the absence of experimental data);

k_c

parameter;

K_pre

precracking stiffness;

K_post

postcracking stiffness;

K_tr

parameter;

L

effective span of simply supported beam;

L_d

development length of rebar;

l_e

embedded length of rebar;

L_p

lap length of longitudinal rebars;

n

modular ratio;

P

point load applied on beam (total load = 2P);

P_u

ultimate point load applied on beam (total ultimate load = 2P_u);

S

spacing of confining stirrups provided along the rebar lap zone;

S_r

gap between rebars in the lap zone;

u

bond strength of spliced rebars with transverse reinforcement;

u_c

bond strength of spliced rebars (without confining stirrups);

u_max

peak bond stress;

u_v

bond strength contributed by the confining stirrups;

α

top rebar modification factor;

α₁

parameter;

α₂

modification factor for bond strength;

δ_s

rebar slippage;

δ_s,max

slippage corresponding to the peak bond stress;

Δ_u

midspan deflection at ultimate state;

ɛ_re

experimental rebar strain at rupture;

ɛ_fu

rupture strain of GFRP rebars;

γ_c

material safety factor for concrete (=1.3 when $f_c^{\mathrm{\prime }}<50\mathrm{MPa}$; =1.5 in all other cases); and

$\mathrm{\varnothing }$

strength reduction factor.

References