Analytical and Empirical Fragility Assessment of Italian Single-Storey Steel Industrial Structures

This study presents a comprehensive numerical investigation aimed at evaluating the seismic vulnerability of single-storey steel industrial buildings representative of the Italian building stock. A simulation framework was developed based on the technological evolution of industrial construction in Italy, considering structural geometry, truss typology, environmental loading conditions, and construction period as the main parameters influencing seismic response. The combination of these variables led to the generation of 336 structural configurations. For each building, member sections were determined through a simulated design procedure consistent with the regulations in force at the time of construction. Finite element models were then developed and subjected to nonlinear static analyses to derive capacity curves in the principal directions. Subsequently, analytical fragility curves were obtained to estimate the probability of reaching different damage states as a function of Peak Ground Acceleration (PGA). These results were compared with fragility curves derived using empirical formulations available in literature. The comparison allowed a critical assessment of the consistency and reliability of different seismic damage estimation approaches. Furthermore, the study validated a new empirical formulation for the derivation of transverse-direction fragility curves, showing improved predictive capability for the considered structural typology.