Nomenclature
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A s
Cross-sectional areas of the steel tube (m
2 )
A c
Cross-sectional areas of the core concrete (m
2 )
α r
Steel ratio of CFST member
f y
Yield strength of steel tube (MPa)
E K
Impact energy (kJ)
m
Mass of drop hammer (kg)
H
Release height of drop hammer (m)
σ y
Initial yield strength surface
σ m
Maximum strength surface
σ r
Residual strength surface
a i
Strength constant, i = 0, 1, 2
a iy
Strength constant, i = 0, 1, 2
a if
Strength constant, i = 0, 1, 2
f c
Unconfined uniaxial compressive strength (MPa)
f t
Unconfined uniaxial tensile strength (MPa)
p
Pressure (kN)
ψ
Tensile-to-compressive meridian ratio
γ
Current failure surface
J 2
Second deviatoric stress invariant
r
Ratio of the current meridian to the compressive meridian
η
Yield scale factor referring to the damage function
λ
Damage function
b 1
Damage constant
b 2
Damage constant
d ¯
ε p
Effective plastic strain increment
d ε
p
ij
Plastic strain increment tensor
r f
Strength dynamic increase factor
E i
Internal energy per initial volume
γ i
Ratio of specific heat
C(μ)
Tabulated pressure as functions of volumetric strain
T (μ)
Tabulated temperature as functions of volumetric strain
d ˜
μ
Proportionality constant
d ε
p
11
Axial plastic strain increment
G
Strain energy (MP m)
h e
Element size (mm)
σ d
Dynamic flow stress (MPa)
σ s
Associated static flow stress (MPa)
C c
Strain rate parameter
P c
Strain rate parameter
E t
Tangent modulus (GPa)
ρ r
Reinforcement ratio