Dynamic Performance of Simply Supported Rigid Plastic Circular Thick Steel Plates Subjected to Localized Blast Loading

Abstract

Close-in explosive charges, such as improvised explosive devices, produce localized blast loadings that can potentially cause damage to property in military and civil structures and/or loss of life. Because the localized short-duration blast pulse affects most severely a small area of a plated structure, the plate’s boundary effects are not as influential as they would be when quasi-static or even a global blast loading is applied, and thus full plate action may not be used. Many common structural forms are composed of individual plated elements, and thus the investigation of localized blast loading effects on plates is an important aspect that leads to understanding the integral behavior. Typically, plates are made of ductile metallic materials, such as steel, which exhibit considerable postyield deformation capacity when subjected to such extreme dynamic loads. An analytical study of the dynamic plastic response of rigid plastic plated structures is the aim of the current study. A circular plate is studied in the present work, and a general form of a localized blast loading function with a spatial variation having a central radial zone with constant pressure and exponentially decaying profile outside the zone is assumed. Assuming that steel exhibits perfectly plastic behavior and considering transverse shear and rotatory inertia effects, using the approach developed previously, results for the permanent transverse displacements and response durations are found in terms of an applied impulsive velocity, which is a function of the applied localized blast load. It is found that the influence of transverse shear is only relevant for small values of ν, or plate radius-to-thickness ratio, which do not correspond to typical plate geometries found in plated structures subjected to blast loading. Both midpoint and support displacement are only significantly affected by transverse shear effects for ν≤5. The same argument is extended to inclusion of rotatory inertia. It is also seen that, for close-in blasts, the effects of transverse shear and rotatory inertia are irrelevant, even for small values of ν.