Can you break me down the difference in Explosive Weight I and Explosive Weight II?

Explosive Weight I and Explosive Weight II?

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.  The standoff for this explosive weight is no longer the 82 feet typical of the 2007 criteria.  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.  The actual stand-off must be used which is from the parking lot to the window/wall in question.

Hope this helps.  Please call if you have any questions.

Stewart P. Jeske, P.E.

JEI Structural - Glazing Systems Engineering

www.jeistructural.com

How experience for design calculations saves time and money

Some glazing contractors don’t budget enough for appropriate engineering calculations (structural calcs) on projects. Those who do, understand the value of industry expertise. Some glaziers brag, “I’ve got a guy that does it on the side.” The truth is, a structural engineer with industry experience will save you time and money.

Structural engineers with glazing system experience are familiar with industry manufactures and have worked with their components and framing, so you’ll end up with system components and anchors that will work. An experienced engineer will always look at the boundary joints to make sure that excessive movement will not compromise the joint water barrier. In addition, years of experience usually results in a quick turn around using better software, specifically for aluminum curtain wall and storefront design.

Experts in aluminum code won’t over design your project. Aluminum design is specialized and requires adherence to the complex 2010 Aluminum Design Manual. This 469 page book larger is larger than the steel code! Few engineers ever pick up aluminum design, due to it’s specialization. University curriculums for structural engineers focus on steel, concrete and CMU. Aluminum is never used in the design of building or bridge structures so most structural engineers just don’t come across it in their everyday work. This type of experience is essential if you want your glazed system to work without problems for years to come.

So next time you need design calculations, hire experience. You’ll save money in the end.

Antiterrorism: Blast-resistant Glazing Systems

The environment of rapidly evolving antiterrorism codes has left estimators and manufacturers in a whirlwind of confusion asking themselves, “Why do blast resistant requirements seem to be a moving target?” It’s important for us to understand what is driving this part of the glazing industry. A great emphasis has been placed on protecting the inhabitants of government buildings from flying shards of glass due to explosion. The U.S. government will be investing great amounts of capital into protective glazing systems during the next 10 to 15 years to make the changes necessary to their existing buildings and for all new construction. The two major codes driving the changes are GSA/Interagency Security Committee Security Design Criteria and the U.S. Department of Defense Unified Facilities Code UFC 4-010-01, Minimum Antiterrorism Standards for Buildings. The UFC code requires all future DoD programming beginning in 2004 to include blast resistant glazing systems. Over the last couple of years we have begun to see many of these projects entering into construction and it’s essentially the same story for the GSA’s programmed projects.

For more insight on this topic see:

http://www.glassmagazine.com/article/commercial/antiterrorism-blast-resistant-glazing-systems-and-moving-target

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Recovery money is starting to flow into the glass and glazing industry. Now is the time to position your company to recieve business.