Glass Blast: Explosive Weight I and Explosive Weight II?
Glass Blast design is an increasingly important topic.
Question
Can you break me down the difference in Explosive Weight I and Explosive Weight II?
Answer
This is the criteria from the 2012 UFC:
Explosive weight I is associated with a larger weight of TNT for a van or truck bomb outside of the base perimeter. Its based on the assumption that a vehicle bomb will not be able to penetrate the base perimeter and/or will be detected at the gate. If we have a facility that is less than 200 feet from the base perimeter/fence, then we must consider explosive weight I. In addition to explosive weight II and its pressure/impulse may govern over the explosive weight II.
Explosive weight II is associated with a smaller weight of TNT simulating a back-pack or smaller bomb that gets past the base gate. So the standoff for this explosive weight is no longer the 82 feet typical of the 2007 criteria. Also now it is based on the new conventional stand-offs that are listed in the tables based on construction type and load bearing/non-load bearing walls. So the actual stand-off must be used which is from the parking lot to the window/wall in question.
So i hope this helps. Please call if you have any questions.
Stewart P. Jeske, P.E.
JEI Structural – Glazing Systems Engineering
816-734-8345
We work exclusively in glass, glazing and metal panel design.
So contact JEI Structural Engineers we are trained to add value to any project.