Empirical Expression for Failure Strain in EBROG-Bonded FRP–Concrete Joints

Notation

a_g

dimension of a square groove (in mm);

b_c

width of a concrete prism (in mm);

b_f

width of an FRP sheet (in mm);

b_f,sg

width of an FRP sheet on a single groove (in mm);

b_g

groove width (in mm);

d_g

groove depth (in mm);

E_f

elastic modulus of an FRP sheet (in GPa);

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

concrete compressive strength (in MPa)

G_f

fracture energy per unit width of an FRP sheet (in N/mm);

$G_f^{P_{\max }}$

fracture energy equivalent to load capacity (in N/mm);

K_g

calibration coefficient of a square groove relation;

$K_g^{\mathrm{\prime }}$

calibration coefficient of a general relation;

l

bond length (in mm);

l_eff

effective bond length (in mm);

n_g

number of grooves arranged under the width of an FRP sheet;

P_avg

average maximum load of a couple of tests (in kN);

P_{Chen and Teng}

load capacity of EBR joints by Chen and Teng’s model (in kN);

P_EBROG

load capacity of EBROG joints by Moghaddas and Mostofinejad’s model (in kN);

P_max

maximum load carried by a bonded FRP sheet (in kN);

R²

coefficient of determination;

S

slip of an FRP sheet at the midwidth of the beginning of a bond (in mm);

t_f

thickness of an FRP sheet (in mm);

ɛ_f,max

maximum strain of an FRP sheet bonded to concrete by the EBROG method;

ɛ_ff,exp

experimental failure strain of an EBROG joint (equal ɛ_f,max);

ɛ_ff,est

estimated failure strain of a bonded FRP sheet by the EBROG method;

β_C

function of the concrete effect;

β_F

function of an FRP sheet; and

β_G

function of a groove.

References