Full-Scale Bending Test Study for PC Hollow Slab Girder Using UHPFRC and Composite Reinforcement Techniques

Acknowledgments

Notation

A_p

area of prestressed reinforcement in tensile part;

A_s

area of reinforcements in bottom flange (tensile part);

$A_s^{\mathrm{\prime }}$

area of reinforcements in top flange (compressive part);

A_sp

area of strengthening steel plate in tensile part;

a_p

distance from resultant point of tensile prestressed reinforcements to the bottom edge of tensile zone;

a_s

distance from resultant point of tensile reinforcements to the bottom edge of tensile zone;

$a_s^{\mathrm{\prime }}$

distance from resultant point of compressive reinforcements to the top edge of compressive zone;

a_t

thickness of concrete or UHPFRC layer above top flange;

a_U

distance from resultant point of UHPFRC under bottom flange to the bottom edge of tensile zone;

b

width of bottom flange;

$b_f^{\mathrm{\prime }}$

width of top flange;

b_w1

thickness of one web;

b_w2

thickness of the other web;

b(x)

net width of girder at calculating location;

C_c

internal axial force of compressive UHPFRC and concrete;

$C_s^{\mathrm{\prime }}$

internal axial force of compressive reinforcement;

E_s

elastic modulus of reinforcement and steel plate;

E_Ut

elastic modulus of UHPFRC in tensile zone;

f_cr1

deformation at midspan section corresponding to P_cr1;

f_cr2

deformation at midspan section corresponding to P_cr2;

f_u

deformation at midspan section corresponding to P_u;

f_y

deformation at midspan section corresponding to P_y;

h

distance from the centroid of strengthening steel plate to the top of the strengthened girder;

$h_f^{\mathrm{\prime }}$

thickness of top flange;

h_r

distance from the centroid of tensile steel reinforcements to the top edge of the strengthened girder;

M

bending moment at midspan section;

$M_{\mathrm{cr}2,c}$

calculated moment at cracking state for reinforcement part;

M_cr2,t

tested moment at cracking state for reinforcement part;

$M_{u,c}$

calculated moment at ultimate state;

$M_{u,t}$

tested moment at ultimate state;

$M_{y,c}$

calculated moment at yielding state;

$M_{y,t}$

tested moment at yielding state;

P_cr1

load as concrete crack start developing in PC girder;

P_cr2

load of incipient cracking in reinforcement part;

P_u

ultimate capacity;

P_y

yield load of the strengthening steel plate;

T_p

internal force of prestressed reinforcements;

T_s

internal force of steel reinforcements in bottom flange;

T_sp

internal force of steel plate in composite strengthening part for bottom flange;

T_U

internal force of UHPFRC in composite strengthening part for bottom flange;

x

distance from calculation position in the compression zone to neutral axis;

x_c

depth of the compressive zone;

Δσ_p

tensile stress increment of prestressed reinforcement;

Δɛ_p

tensile strain increasement of prestressed reinforcement;

ɛ_c

compressive strain of concrete in PC girder;

${\epsilon }_{c,x}$

compressive strain of concrete at position of x;

ɛ_hc

compressive strain of concrete or UHPFRC above the top flange;

${\epsilon }_{hc,x}$

compressive strain of UHPFRC or concrete at position of x;

ɛ_s

tensile strain of reinforcement in bottom flange;

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

compressive strain of reinforcements in top flange;

ɛ_sp

tensile strain of steel plate;

ɛ_spy

yielding strain of steel plate;

ɛ_sy

yielding strain of reinforcement in bottom flange;

ɛ_Ut

tensile strain of UHPFRC;

ɛ_Utu

ultimate tensile strain of UHPFRC;

${\sigma }_c({\epsilon }_{c,x})$

compressive stress of concrete corresponding to ${\epsilon }_{c,x}$;

${\sigma }_{hc}({\epsilon }_{hc,x})$

compressive stress corresponding to ${\epsilon }_{hc,x}$;

σ_s

tensile stress of reinforcement in bottom flange;

${\sigma }_s^{\mathrm{\prime }}$

compressive stress of reinforcement in top flange;

σ_sp

tensile stress of steel plate;

σ_spy

yielding stress of steel plate;

σ_sy

yielding stress of reinforcement in bottom flange;

σ_Ut

tensile stress of UHPFRC;

σ_Ute

velastic stress of tensile UHPFRC; and

σ_Utu

ultimate tensile stress of UHPFRC.

References