Interdisciplinary Journal of Civil Engineering

Interdisciplinary Journal of Civil Engineering

Vulnerability Assessment of Reinforced Concrete Columns under Varying Axial Loads Using the Park–Ang Damage Index

Document Type : Original Article

Authors
Masoumeh Afagh
Fatemeh Z. Dokhanian
Mahmoud R. Shiravand
Faculty of Civil, Water and Environmental Engineering, Shahid Beheshti University, Tehran Iran
10.48308/ijce.2026.245593.1027
Abstract
Reinforced concrete (RC) columns are critical load-bearing components of structural systems, and their cyclic behavior is strongly influenced by the axial load ratio. Variations in the axial load ratio affect the stiffness, strength, ductility, energy dissipation capacity, and damage accumulation of RC columns. Therefore, evaluating the effect of axial load ratio is essential for accurate seismic performance assessment. In this study, the influence of different axial load ratios on the damage evolution of RC columns under cyclic loading was investigated using a nonlinear finite element model validated against experimental data. The Park–Ang damage index was used to evaluate damage evolution. The results showed that increasing the axial load ratio enhanced the initial stiffness and load-bearing capacity but reduced the deformation and energy dissipation capacities, resulting in faster damage accumulation. The maximum cumulative hysteretic energy and the highest Park–Ang damage index were observed at an axial load ratio of 0.20, highlighting the significant influence of axial load ratio on damage evolution. Comparison with experimental observations showed that although the Park–Ang damage index captures the overall trend of damage evolution, its values cannot accurately represent the actual damage states without calibration.
Keywords
Reinforced Concrete Columns
Axial Load Ratio
Cyclic Loading
Damage Evolution
Park&ndash
Ang Damage Index
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Interdisciplinary Journal of Civil Engineering
Volume 2, Issue 2 - Serial Number 6
Spring 2026
Pages 120-136