ARBITRARY LAGRANGIAN EULERIAN ANALYSIS OF THE NEPTUNE FOUNTAIN IN FLORENCE SUBJECTED TO BLAST LOADS

The present work aims to study the detonation of an explosive charge using a numerical approach. It continues a previous investigation conducted on the Neptune Statue located in Signoria Square, Florence. This case study has been proposed by the University of Florence with the aim of protecting the artistic and cultural heritage: thus, the question is about the blast effects on the statue in the case of a terrorist attack, so as to predict the damage and find possible mitigation or securing measures. In previous work, the focus was on the effects generated by the shock wave of a 45 kg TNT charge explosion placed on the pavement just outside the balustrade 8.8 m from the target. Because of the complexity of the geometry, laser scanning was necessary to obtain a numerical model of the statue, which resulted in a geometric model and finally a mesh. The pressure loads were estimated with the semi-empirical formulas. It is now desired to continue the investigation by constructing a numerical model simulating the explosion, so as to get rid of the limitations of the semiempirical formulations by increasing the accuracy of the analysis. The explicit LS_Dyna solver was used for this purpose. An arbitrary Lagrangian-Eulerian (ALE) approach was chosen, the use of which is already widely established in the literature. Here we limited ourselves to deriving the pressure load as a function of time and validating the numerical model with the results predicted by semiempirical theories. Neither damage analysis nor possible mitigation measures were addressed, which will be the subject of a future publication. For the time being, a rigid material was assigned to the statue; this greatly reduced the computational cost of the analysis.