Application of CFRP Tendons to Novel Connections of Precast Concrete Deck Panels: Experiments and Analytical Models

Acknowledgments

Notation

A_c,N

actual projected area of the concrete cone of the single-welded stud with two steel studs;

$A_{c,N}^0$

projected area of the concrete cone for one stud rod with adequate spacing and edge distance;

A_c,V

actual projected area of shear failure area for a welded stud;

$A_{c,V}^0$

projected area of the shear failure area for a steel stud with adequate spacing and edge distance;

A_f

total cross-sectional area of CFRP tendons;

b

width of PCDPs;

c_cr,N

minimum edge distance to develop the intact concrete cone;

c_max

maximum edge distance;

c_min

minimum distance of welded stud to the edge;

c₁

distance from the loading position to the concrete edge;

C_c

compressive force of concrete;

D

distance between the studs and specimen center for specimen with two studs;

D_in

distance between the internal studs and specimen center for specimen with four studs;

D_out

distance between the outermost studs and specimen center for specimen with four studs;

d_nom

diameter of the steel stud;

E_c

elasticity modulus of concrete and UHPC;

E_f

elasticity modulus of CFRP tendon;

E_s

elasticity modulus of ordinary reinforcement;

F_t

tension provided by the single-welded stud;

F_t1

horizontal component from axial force along the direction of the stud rods;

F_t2

horizontal component from shear force perpendicular to the stud rods;

f_c

stress of concrete under compression;

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

compressive strength of concrete cylinder;

f_cc,200

cubic compressive strength of concrete with the length of 200 mm;

f_cu

cubic concrete compressive strength;

f_c2

compressive strength of concrete at the top of the connections when it is damaged;

f_frpt

stress of CFRP tendon;

f_pu

fracture stress of the CFRP tendon;

f_s

tensile stress of ordinary reinforcement;

$f_t^{\mathrm{\prime }}$

tensile strength of concrete and UHPC;

f_y

yield stress of ordinary reinforcement;

h_ef

effective height of stud;

h_f

distance from CFRP tendons at the position of the connection to the top of the concrete;

h_t

distance from welded stud at the position of the connection to the top of the concrete;

K_c

ratio of the second stress variant;

l_f

length of the steel stud;

L

anchorage distance;

M

moment capacity of PCDPs;

M_cr

cracking moment;

M_model

moment obtained by FE model;

M_s

moment capacity of PCDPs with straight post-tensioned CFRP tendons;

M_test

moment obtained by test;

M_u

peak moment;

M_y

yield moment;

n

quantity of welded studs;

N_u,c

axial force along the direction of the stud rods;

R

radius of curved post-tensioned CFRP strands;

s_max

the maximum spacing between two studs;

V_u,c

shear force perpendicular to the stud rods;

x_a

height of the stress diagram from the neutral axis to the point where the concrete stress reaching f_c2;

x_c

depth of the neutral axis in the section;

y

height from the neutral axis;

y_c

distance from the neutral axis to the centroid of concrete compressive force;

β

angle between the stud rod and horizontal direction;

β₁

ratio of the height of the concrete equivalent rectangular stress block to the depth of the neutral axis;

Δ_u

peak deflection;

Δ_y

yield deflection;

ɛ_c

strain of concrete under compression;

${\epsilon }_c^t$

compressive strain of the top concrete when the CFRP tendons present fracture;

ɛ_co

concrete strain corresponding to the maximum stress;

ɛ_cu

ultimate strain of concrete;

ɛ_d

strain at the decompression state;

ɛ_f

strain caused by external loads;

ɛ_frpt

strain of CFRP tendon;

ɛ_fu

strain of CFRP tendons due to the external forces when the critical state is reached;

ɛ_pe

effective strain caused by the initial prestressing force after all stress losses;

ɛ_pu

ultimate tensile strain in CFRP tendon;

ɛ_s

tensile strain in ordinary reinforcement;

${\epsilon }_t^{\mathrm{\prime }}$

tensile strain of concrete and UHPC;

ɛ_u

ultimate strain in ordinary reinforcement;

ɛ_y

yield strain in ordinary reinforcement;

η

flow potential eccentricity;

θ_p

angle between the CFRP tendon and horizontal direction;

ρ_fc

balanced ratio of CFRP tendon;

σ_b0/σ_c0

ratio of the initial axial compressive yield stress to the initial uniaxial compressive yield stress;

σ_t

stress of weld stud;

υ

Poisson’s ratio; and

ψ

dilation angle.

References