Influence of Metal–Composite Strengthening on the Behavior of Reinforced Concrete Columns under Various Load Eccentricities
Abstract
Influence of Metal–Composite Strengthening on the Behavior of Reinforced Concrete Columns under Various Load Eccentricities
Incoming article date: 01.10.2025This paper presents a comparative analysis of test results for reinforced concrete columns strengthened with steel and carbon fiber–reinforced polymer (CFRP)-based composite materials. Particular emphasis is placed on deformability and stiffness characteristics. The experimental program included 21 columns fabricated from normal-weight concrete with a target compressive strength class of B25–B30. All specimens had a rectangular cross-section of 250 × 125 mm (width × height) and two different lengths—1200 mm and 2400 mm—corresponding to slenderness ratios (λₕ) of 10 and 20, respectively.
The columns were subjected to axial loading with three eccentricity values: e₀ = 0; e₀ = 2.0 cm (0.16h); and e₀ = 4.0 cm (0.32h). Additional test variables included internal and external steel reinforcement configurations, as well as the spacing and cross-sectional area of the composite strengthening layers.
The study investigates the effects of the aforementioned parameters on the performance of columns strengthened with CFRP composites and steel elements. The results demonstrate that strengthened reinforced concrete columns—despite having identical geometry and being tested under the same load eccentricities—exhibit significantly different structural responses.
The primary objective of this research was to determine the influence of strengthening element stiffness on the deformability of slender strengthened columns, and the effect of load eccentricity on the required stiffness of strengthening components.Keywords: reinforced concrete, column, steel, testing, composite material, CFRP, strengthening