Computational confinement analysis of hollow circular concrete columns using a finite layer constitutive framework

Optimization of structural elements in reinforced concrete design is central to modern engineering efforts to reduce self-weight while maintaining or improving strength and ductility, especially in seismic-prone regions. This study presents a comprehensive confinement analysis of Hollow Circular Concrete Sections (HCS) as compared to their Solid Circular Section (SCS) counterparts. Employing a computationally efficient, non-linear finite-layer framework, it develops a numerical procedure that evaluates confined strength using incremental–iterative moment-of-area computations based on a secant-stiffness formulation embedded in a custom finite-layer model. The study systematically investigates various HCS geometries with different inner-to-outer diameter ratios, longitudinal and lateral reinforcement arrangements, and concrete strengths ranging from 3.4 to 5.4 ksi. The confinement effects are analyzed using a modified Mander-type concrete model adapted for hollow geometries, with attention to stress distribution across the annular cross-section. Axial–moment interaction diagrams are produced for a wide range of experimental configurations, allowing direct performance comparison. Results show that, with proper detailing, HCS can achieve confinement performance comparable to that of equivalent SCS, particularly when tri-axial reinforcement is used. Overall, the study demonstrates the potential of hollow concrete columns as a sustainable and high-performance alternative to traditional solid members, paving the way for advanced structural typologies in both high-rise and infrastructure applications.