Flexural behaviour of lightweight aggregate concrete columns Available to Purchase

The flexural performance of lightweight concrete (LWC) columns was evaluated and limitations of ACI 318-19 in predicting the flexural crack (M_cr) and maximum (M_n) moments, as well as the minimum amount of transverse reinforcing bar (A_sh(ACI)), were examined. Six LWC columns with different amounts of transverse reinforcing bar (A_sh), compressive strengths of concrete (f_c′) and concrete types were prepared and tested under constant axial and cyclic lateral loads. The test results show that ACI 318-19 agrees well with the M_cr of tested columns, considering the lower tensile stress of LWC columns by introducing modification factors (λ) (all-lightweight concrete, λ = 0.75; sand–lightweight concrete, λ = 0.85) for the fracture modulus of concrete (f_r). In addition, ACI 318-19 underestimates M_n, irrespective of A_sh, f_c′ and concrete type. The ductility of LWC columns increased with the increase in volumetric transverse reinforcing bar index (ω_vh). The increasing rate was lower than that of normal-weight concrete (NWC) columns. The displacement ductility ratio (μ_Δ), work damage indicator (W₈₀) and equivalent damping coefficient (ξ₈₀) of a column with 1.0A_sh(ACI) were, on average, 30, 36 and 18% lower in LWC than NWC columns. Consequently, double the A_sh(ACI) was required to retain a flexural ductility equivalent to that of a NWC specimen.