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
My question is what is the frame deflection limited to? L/160 or is this L/160 per lite.
ReplyDeleteFor example: 21 ft. single span mullion with 4 lites. Would it be L/(21’ x 12) or would you need to draw the deflection of the mullion and measure L/160 for each individual lite.
Mike Jarvis
Project Engineer
Kawneer Company, Inc.
Hi Michael,
DeleteI’ve thought about that same question several times in the past.
The UFC 4-010-01 identifies the criteria as limiting the supported edge of the glass to 1/160 of the supported length. We have typically taken the approach and confirmed that if we limit the full span to 1/160 the individual supported lengths or segments fall within that criteria as well.
What are your thoughts?