Flexural Behavior of GFRP–Aluminum Space Truss Strengthened with Prestressed CFRP Tendons: Experimental and Theoretical Study

Data Availability Statement

Acknowledgments

Notation

A_B

cross-sectional area of solid-web beam (mm²);

A_S

cross-sectional area of strut (mm²);

A_T

cross-sectional area of tendon (mm²);

B

total flexural stiffness of equivalent continuum beam (kN · mm²);

B₀

flexural stiffness of the upper and lower surface layers (kN · mm²);

d

length of GFRP tube with PTTCs and BBCs (mm);

d_sb

length of solid ball (mm);

d_sl

length of sleeve (mm);

d_sp

length of sealing plate (mm);

d_PTTC

length of PTTC (mm);

E_B

elastic modulus of solid-web beam (GPa);

E_S

elastic modulus of strut (GPa);

E_T

elastic modulus of tendon (GPa);

(EA)_EQ

modified axial stiffness (GPa · mm²);

(EA)_GFRP

axial stiffness of GFRP tube (GPa · mm²);

(EA)_PTTC

axial stiffness of PTTC (GPa · mm²);

(EA)_sb

axial stiffness of solid ball (GPa · mm²);

(EA)_sl

axial stiffness of sleeve (GPa · mm²);

(EA)_sp

axial stiffness of sealing plate (GPa · mm²);

EI

equivalent flexural stiffness (kN · mm²);

(EI)_EQ

modified flexural stiffness (kN · mm²);

(EI)_GFRP

flexural stiffness of GFRP tube (kN · mm²);

(EI)_PTTC

flexural stiffness of PTTC (kN · mm²);

(EI)_sb

flexural stiffness of solid ball (kN · mm²);

(EI)_sl

flexural stiffness of sleeve (kN · mm²);

(EI)_sp

flexural stiffness of sealing plate (kN · mm²);

e, e₁, e₂

eccentricity from the CFRP tendon to the centroid of beams (mm);

${\overline{F_{\mathrm{B}1}}}^{\mathrm{T}(\mathrm{F})}$

axial force of the beams under virtual force (kN);

${\overline{F_{\mathrm{BP}}}}^{\mathrm{T}(\mathrm{F})}$

axial force of the beams under concentrated load (kN);

${\overline{F_{\mathrm{TD}1}}}^{\mathrm{T}(\mathrm{F})}$

axial force of the diagonal CFRP tendon under virtual force (kN);

$F_{\mathrm{TDP}}^{\mathrm{T}(\mathrm{F})}$

axial force of the diagonal CFRP tendon under concentrated load (kN);

${\overline{F_{\mathrm{TH}1}}}^{\mathrm{T}(\mathrm{F})}$

axial force of the horizontal CFRP tendon under virtual force (kN);

$F_{\mathrm{THP}}^{\mathrm{T}(\mathrm{F})}$

axial force of the horizontal CFRP tendon under concentrated load (kN);

${\overline{F_{\mathrm{S}1}}}^{\mathrm{T}(\mathrm{F})}$

axial force of struts under virtual force (kN);

${\overline{F_{\mathrm{SP}}}}^{\mathrm{T}(\mathrm{F})}$

axial force of struts under concentrated load (kN);

G

material shear modulus of GFRP web member (GPa);

h

height of space truss girder or equivalent continuum beam (mm);

h₁, h₂

vertical distances from the centroid of the upper and lower surface layers to that of equivalent continuum beam (mm);

K

shear stiffness of solid-web beam (kN · mm²);

l

length of space truss girder or equivalent continuum beam (mm);

${\overline{M_{\mathrm{B}1}}}^{\mathrm{T}(\mathrm{F})}$

section moment of the beam under virtual force (kN · mm);

$M_{\mathrm{BP}}^{\mathrm{T}(\mathrm{F})}$

section moment of the beam under concentrated load (kN · mm);

N

axial force of truss member (kN);

P

concentrated load (kN);

Q

shear force (kN);

q

uniformly distributed load;

T₀

initial prestress (kN);

T₁

virtual force (kN);

t

thickness of equivalent continuous beam (mm);

w

midspan deflection (mm);

y

equation of the lateral deflection curve (dimensionless);

γ

shear strain (dimensionless);

δ

shear deformation (mm);

δ₁₁, Δ_1P

relative deflection of CFRP tendon (mm);

ΔP

incremental difference (kN);

Δω

incremental difference (mm);

η

girder-to-tendon stiffness ratio (dimensionless);

μ

cross-sectional shape factor (dimensionless);

ν

Poisson’s ratio (dimensionless);

ξ

shear influence coefficient (dimensionless); and

φ

angle between web member and the plane of the lower chords (rad).

References