Numerical prediction of debris loads on underground structures following progressive collapse of multi-story buildings

This paper presents a comprehensive methodology for analyzing static loads acting on underground structures due to debris accumulation following the progressive collapse of above-ground, multi-story, reinforced concrete buildings. A large set of frame-slab type structures was parametrically generated and numerically collapsed using custom Python scripting integrated with Abaqus/Explicit. The debris characteristics, such as surface footprint, height, and volume, were calibrated based on empirical data from recent war-related building collapses in Ukraine. The simulations accurately reflected real-world rubble behavior by selecting optimal debris parts (elements) sizes and credible distributions. A novel numerical fitting method for three-dimensional debris fields was developed, enabling virtual validation of load conditions that would otherwise be prohibitively expensive to test experimentally. The results provide a robust foundation for ongoing updates of the international guidelines addressing rubble-induced static loads on buried structures, especially in the context of warfare or progressive collapse scenarios.