Constitutive models of constrained concrete in cross-shaped PEC column under axial compression

• Published in: Journal of constructional steel research Vol. 215; p. 108533
• Main Authors: Li, Guofei, Li, Yuanping
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2024
• Subjects: Axial compressive ultimate bearing capacity; Constrained concrete; CPEC column; Limit equilibrium method; Stress-strain constitutive model; Limit equilibrium method; Stress-strain constitutive model; CPEC column; Constrained concrete; Axial compressive ultimate bearing capacity
• ISSN: 0143-974X
• DOI: 10.1016/j.jcsr.2024.108533

Based on the influence of lateral constraints, there are two categories of constraint areas within a cross-shaped partially encased composite (CPEC) column: strong constraint areas (SCAs) and weak constraint areas (WCAs). Due to the diverse constraint effects of profile steel on concrete, dissimilar stress-strain constitutive models are exhibited by SCA and WCA, and they contribute differently to the bearing capacity of columns. Based on the constraint mechanism of the CPEC column, the methodologies for partitioning the constraint areas and determining effective constraint coefficients and strength enhancement coefficients of concrete are proposed to establish the constitutive model of constrained concrete. A formula that accounts for the constraint effect is proposed for estimating the axial compressive ultimate capacity of CPEC columns based on the limit equilibrium method. The study demonstrates that the strength of concrete in SCA is significantly enhanced compared with unconstrained concrete, resulting in an increased bearing capacity. The calculated axial load-displacement curves of columns using the derived constrained concrete constitutive models in this study are in good agreement with experimental results. The derived axial compressive ultimate bearing capacity formula quantifies the constraint effect of concrete with high computational accuracy. •Concrete exists strong and weak constraint areas because of steel's lateral stress.•Interaction mechanisms distinctly affect the mechanical properties of concrete.•Constrained concrete constitutive models are based on the constraint mechanism.•Load capacity formula by limit equilibrium method can quantify constraint effect.