Infiltration of Airblast Into Buildings Through Glazed Openings
The Explosives Safety Manual contains a number of methodologies which can be used to estimate the level of blast pressure infiltrating a building through openings. These are applicable to open vents and typically do not consider the effect of window glass.
A recent set of experiments was conducted using reinforced concrete cubicles, each with a single glazed opening on its faÁade. These tests provide an important and useful data set for quantifying the level of attenuation achieved as the blast wave interacts with the window, enters the cubicle, and generates pressure inside the cubicle. Some of the experiments also measured blast pressures on the front and back face of computer monitors inside the room, providing additional information regarding the uniformity of the pressure within the room.
By using this data and comparing it to the various TM 5-1300 methods, an assessment of these methods can be made and a preferred methodology selected. Of these, the infill pressure algorithm (TM 5-1300, section 2-15.5) represented the test data most accurately, albeit with significant conservatism. A simple adjustment factor was derived (as a function of the scaled distance from the charge) which eliminates that conservatism and provides an easy-to-use method for computing the blast pressure infiltrating a room through a glazed opening.
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