Numerical analysis of the blast resistance of emergency population shelters subjected to nuclear explosion loading

Abstract

A parametric finite element analysis of an emergency reinforced concrete shelter designed in compliance with current regulations (C25/30 concrete, roof slab 0.25 m, soil overburden 1.0 m) subjected to an air-burst nuclear explosion (W = 1–10 kT, R = HOB = 500 m) was performed using the explicit solver Ansys LS-DYNA on the Okeanos supercomputer. A plane-strain slice model (~202,000 elements) was adopted. The blast load was characterised by a Friedlander pressure–time profile derived from the Kinney–Graham empirical equations with a nuclear decay-coefficient correction.
The results indicate a strongly nonlinear structural response: midspan roof-slab deflection increases from 12 mm (1 kT) to 647 mm (5 kT, i.e. 2.6 times the slab thickness). The transition from plastic behaviour to collapse occurs between 4 and 5 kT. Progressive structural failure is observed at W ≥ 7 kT. The ultimate blast resistance of the analysed shelter is estimated at 5–7 kT, corresponding to a reflected overpressure of 276–379 kPa.