a, μ	Curve-fitting constants in Equation (2)
φ, γ	Curve-fitting constants in Equation (3)
ζ, Φ	Curve-fitting constants in Equation (7)
k, q	Curve-fitting constants in Equation (8)
λ, ξ	Curve-fitting constants in Equation (9)
c	Cohesion of lightweight aggregate concrete
σ1, σv	Axial stress
σ2, σ3, σw	Confining Pressure
σ u	Peak stress
σ 0	Uniaxial compressive strength of concrete
σ	Stress
$\overline{\sigma }$	Octahedral normal stress
τ	Shear stress
τ u	Peak shear stress
ε	Axial strain
ε u	Uniaxial compression strain
LAC	Lightweight aggregate concrete
NAC	Natural aggregate concrete
LAC20	Design strength of 20 MPa lightweight aggregate concrete
LAC30	Design strength of 30 MPa lightweight aggregate concrete
LAC40	Design strength of 40 MPa lightweight aggregate concrete