Fragility Analysis of RC Structure Subjected to Blast Loading By Considering and Ignoring Soil Structure Interaction

This research evaluates the fragility of reinforced concrete (RC) structures in response to blast loads, with an emphasis on the effects of soil-structure interaction (SSI). With rising global threats, understanding Reinforced Concrete performance during extreme forces is essential. Conventional analyses often neglect soil-structure relationships, leading to inaccurate predictions of structural responses and failure likelihood during blasts. This research systematically examines RC structures, incorporating both SSI and non-SSI scenarios. A 3D finite element model using SAP2000NL emulates behavior under dynamic loading, with foundational soil modeled as a Winkler spring system. Results reveal significant discrepancies in responses, emphasizing that ignoring SSI can lead to unsafe design choices and underestimations of damage probabilities. A fifteen-storey reinforced concrete moment-resisting frame was modeled using SAP2000NL, factoring in realistic materials, blast parameters, and soil conditions. The study evaluated the structure's response to varying TNT weights (200 kg, 500 kg, and 750 kg) and explosion distances (5 m, 15 m, and 30 m), comparing fixed-base and flexible-base models. Blast loads were applied through equivalent static pressure derived from empirical curves, with key parameters like peak lateral displacement, inter storey drift, and base shear analyzed via time-history analysis. The findings indicated that incorporating soil-structure interaction (SSI) significantly increased structural responses and damage probabilities, emphasizing the necessity of SSI considerations in blast resistant design for critical infrastructures.