Seismic Fragility Assessment of Irregular Reinforced Concrete Structures Using Probabilistic Modeling

Abstract

The seismic performance evaluation of irregular reinforced concrete structures has become increasingly important due to their higher vulnerability to earthquake-induced damage and structural instability. This study presents a seismic fragility assessment of irregular reinforced concrete structures using probabilistic modeling techniques to evaluate structural reliability and damage probability under varying seismic intensities. The proposed framework integrates nonlinear dynamic analysis, probabilistic seismic hazard assessment, and fragility curve development to analyze the structural response of irregular buildings with geometric and mass irregularities. A computational methodology based on finite element modeling and incremental dynamic analysis was employed to simulate earthquake loading conditions and assess displacement response, inter-story drift, stress distribution, and failure mechanisms. Statistical and probabilistic approaches were utilized to estimate the likelihood of different damage states, including slight, moderate, extensive, and collapse conditions under multiple seismic scenarios. The analytical results demonstrated that structural irregularities significantly influenced seismic vulnerability by increasing torsional effects, stress concentration, and deformation demands compared with regular reinforced concrete structures. The developed fragility models provided accurate prediction of damage probabilities and structural performance under uncertain seismic conditions. Furthermore, the study identified critical parameters affecting seismic resilience, including stiffness distribution, structural configuration, and material properties. The findings conclude that probabilistic fragility assessment offers an effective approach for evaluating the seismic safety and risk performance of irregular reinforced concrete structures. The proposed methodology contributes to the advancement of performance-based earthquake engineering by supporting improved structural design, retrofitting strategies, and disaster risk mitigation for earthquake-resistant urban infrastructure.