Insights into finite element simulations of semi-buried box structures under combined blast and fragment loads

This paper presents insights into the finite element (FE) simulation of semi-buried box structures under combined blast and fragment loads. Semi-buried box structures are important military protective structures of national and strategic importance and must withstand extreme loading threats from weapon detonations. Herein, the dynamic response of a semi-buried box structure with a blast door subjected to cased explosive charge detonations is investigated using the finite element simulation technique considering both blast and fragment loading. A series of analyses are performed using FE simulation software LS DYNA to estimate the intricate effects of two simultaneous cased charge detonations on the semi-buried box structure by varying the cased loading and point of fragment impact. At first, a comparative study of the semi-buried box structure with and without the protective sand layer is performed under different cased loading. Thereafter, the response of the semi-buried box structure with the protective sand layer is studied under different cased loading along with different points of fragment impacts. Results indicate that the present simulation technique is proficient in estimating the response of the semi-buried box structure under cased loading.