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CIB Conferences

Abstract

The axial load-bending moment about single axis (P-M) interaction diagram characterizes the uniaxial-bending load capacity of CFRP-strengthened reinforced concrete (RC) columns. Although numerous CFRP-confined concrete models have been proposed in previous studies, the influence of different CFRP-confined concrete models on the P-M interaction behavior of columns has not yet been fully examined. This study investigates the effects of various confined concrete models on the P-M interaction diagrams of a prototype CFRP-strengthened RC columns. Sectional analysis is carried out based on the plane-section assumption and internal force equilibrium, in which the column’s cross-section is discretized into strips parallel to the neutral axis. Different confined concrete models are employed to describe the material behavior of concrete in the analysis, while the cross-sectional geometry and computational procedure are kept unchanged to ensure a consistent basis for comparison. The results obtained show that the differences among the applied confined concrete models lead to pronounced variations in the characteristic indices of the P-M interaction diagram, including the axial compressive capacity Pmax, the maximum bending moment Mmax, and the interaction envelope area (IA). In contrast, when the P-M interaction diagrams are normalized by their corresponding extreme values, the relative shapes of the envelopes are found to be nearly identical over the entire loading domain. The findings indicate that the compressive strength of confined concrete governs the characteristic values of the P-M interaction diagram, whereas the normalized shape of the interaction curves remains largely insensitive to the selection of the particular confined concrete model. This study provides a rational basis for evaluating the effectiveness of individual CFRP-confined concrete models on the load capacity of strengthened RC columns when subjected to uniaxial bending.

Keywords

Reinforced concrete columns, P-M interaction diagram, CFRP-confined concrete model, Uniaxial bending, Sectional analysis

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