Flexural Crack Performance of the Steel–GFRP Strips–UHPC Composite Deck Structure

Data Availability Statement

Acknowledgments

Notation

A_c

cross-sectional area of UHPC;

b_s

width of the flange steel plate;

b_w

thickness of the web;

c

thickness of the UHPC cover;

d

diameter of the reinforcement bar;

E_c

elastic modulus of UHPC;

E_g

elastic modulus of GFRP;

E_s

elastic modulus of steel;

F

external load;

f_ut

tensile strength of the UHPC plate;

h_c

thickness of the UHPC plate;

h_g

thickness of the GFRP plate;

h_u

thickness of UHPC where the strain has not reached the strain-hardening value;

h_s

distance from the center of the reinforcement bar to the upper surface of the UHPC plate;

h_sy

unyielding height of the compression side of the I-steel beam;

h_tb

thickness of the lower flange of the steel plate;

h_tu

thickness of the upper flange of the steel plate;

h₅

distance from the neutral axis to the upper edges of the I-steel beam web;

h₆

distance from the neutral axis to the lower edges of the I-steel beam web;

h₁, h₃, h₄, h₇

distance from the centroid of each component to the neutral axis, respectively, as shown in Fig. 12;

k

influence coefficient of thickness of UHPC cover;

L

horizontal distance from the loading point to the fulcrum position of the composite slab;

L′

calculated length of the composite beam;

l_g

distance from the centroid of the pressure of the GFRP plate to the neutral axis;

l_cr

average crack spacing;

l_lr

transmission length considering bonding slip;

l₂

distance from the neutral axis to the resultant point of tensile force of the strain-hardening part, once the UHPC is cracked;

l₃

distance from the neutral axis to the resultant point of tensile force of the elastic part, once the UHPC is cracked;

N_c

tensile forces of the UHPC;

N_s

tensile forces of the reinforcement bar;

N_ut

axial forces of the UHPC plate in the tensile zone;

N_sr

axial forces of the reinforcement bar;

N_uc

axial forces of the UHPC plate in the compression zone;

N_gc

axial forces of the GFRP plate in the compression zone;

N_uy

axial force of strain hardening;

N_gt

equivalent tensile force of the GFRP plate;

N_st

tensile force of the upper flange plate;

N_wt

tensile force of the web of the I-steel beam;

N_wc

pressure of the web of the I-steel beam;

N_sc

pressure of the lower flange of the I-steel beam;

N_t1

axial force of the elastic parts after UHPC cracking;

N_ut2

tensile force of the strain-hardening parts once the UHPC is cracked;

N_ut1

tensile force of the elastic parts once the UHPC is cracked;

N_ut3

equivalent tensile force after the UHPC layer full-section is stress hardened;

N_sr1

tensile force of the reinforcement bar when it was yielding;

N_wc1

pressure force of the I-steel beam web in the regions below the neutral axis where the stress of the I-steel beam was unyielding;

N_wc2

pressure force of the I-steel beam web in the regions below the neutral axis where the stress of the I-steel beam was yielding;

N_sc1

pressure of the lower flange of the I-steel beam when it was yielding;

n

number of reinforcements;

P_ut

maximum measured load;

w_smax

maximum crack width at the centroid of longitudinal reinforcement;

w_umax

maximum crack width at the upper surface of the UHPC plate;

y₀

distance from the neutral axis to the surface of the UHPC plate;

α_c

coefficient related to the influence of concrete extension between cracks, for flexural and eccentric compression members, the value is 1.0, for eccentric tension and axial tension members, the value is 1.1, for flexural and eccentric compression members, the value is 0.77, for other members, the value is 0.85;

α_cr

stress characteristic coefficient of the component;

α_e

ratio of the elastic modulus of the reinforcement bar to the elastic modulus of UHPC;

β

coefficient of strain distribution taken as 0.6;

$\epsilon$

strain;

${\epsilon }_c$

strain of the UHPC;

${\epsilon }_{cm}$

average strain of the UHPC;

${\epsilon }_s$

strain of the reinforcement bar;

${\epsilon }_{sm}$

average strain of the reinforcement bar;

${\epsilon }_{s1}$

strain of the upper surface of the GFRP plate;

${\epsilon }_{sr}$

strain of the reinforcement bar;

σ_sr

reinforcement stress of the cracked section;

${\epsilon }_{ut}$

strain of the upper surface of the UHPC plate;

${\epsilon }_{s2}$

strain of the lower surface of the GFRP plate;

φ

bending curvature of the section;

κ

reduction coefficient of tensile strength of the UHPC after cracking, this paper uses the calculation formula given in Bastien-Masse et al. (2016), taken as 0.7;

μ

maximum crack width corresponding to the maximum load;

μ

perimeter of the reinforcement;

ρ_te

effective reinforcement ratio of the UHPC;

τ_l

coefficient related to long-term effect;

τ_s

coefficient of crack width related to short-term effect, for flexural and eccentric compression members, the value is 1.66, for eccentric tension and axial tension members, the value is 1.9;

τ_tm

average bonding strength between the reinforcement bar and the UHPC;

ω_ut

midspan deflection corresponding to the ultimate load;

ψ

coefficient of inhomogeneity of the reinforcement strain distribution; and

ζ

coefficient of average crack spacing, for eccentric tensile members, the value is 1.66, and for axial tensile members, the value is 1.1.

References