Abstract
Blast waves exhibit both positive and negative phases. The relative magnitude of these phases is a function of standoff distance from the explosion source to targets of interest. When an incident blast wave reaches a target building, the blast wave reflects off the front wall (i.e., that facing the blast source). Both the positive and negative phases of the blast wave are enhanced by the reflection process. A fully reflected blast wave would be produced if an incident blast wave reflected from an infinitely tall and wide wall in a normal orientation. However, when an incident blast wave reflects off a wall of finite size in a normal orientation, rarefaction waves are created at the wall edges and roof, and these rarefactions sweep down from the roof and inward from sides. These rarefaction waves result in a clearing effect for both the positive and negative phases. Clearing relieves some of the applied blast load on the reflected wall for the positive phase. However, this is not always the case for the negative phase. As shown in PVP2022-84288[1], clearing may either relieve or enhance the applied negative phase blast load, depending on the blast wave profile and the wall dimensions.
This paper extends the referenced prior study by examining negative phase clearing as a function of building dimensions and non-planar blast waves. The negative phase blast load adjustment factor (i.e., the ratio of cleared to fully reflected blast load) distribution on the front wall is determined. The purpose of this study is to generate a database of negative blast load clearing for engineering modeling applications.
