FUTURE CHANGES TO UFC CODE / ASTM F2248 STANDARD

For the past several years, the Unifed Facilities Criteria (UFC 4-010-01) has been the governing code for all U.S. Department of Defense (DoD) blast mitigation projects.  Referencing the current ASTM F2248-03 standard, the UFC provides a guideline for determining an appropriate static design blast pressure for both framing and connections of blast resistant glazing systems.
Surprisingly, many engineers and glazing contractors are unaware of the requirements set forth by ASTM F2248-03 for the design of framing connections for blast resistant glazing systems.  ASTM F2248-03 specifies connection design loads of at least 2.0 times the magnitude of the 3-second equivalent design load or the glazing resistance as determined from ASTM E1300, whichever is greater.  Often the glazing system connections to the main structure are only designed to resist 2.0 times the 3-second equivalent design load, despite the glazing resistance of the system.

The UFC 4-010-01 is currently undergoing revisions that should clairify blast design loads and reference a more stringent version of the ASTM F2248 standard (ASTM F2248-09). The revised ASTM F2248-09 sets forth the following criteria for the design of blast resistant framing connections to the main structure:

a.       2.0 times the magnitude of the load resistance of the blast resistant glazing if the maximum air blast pressure is greater than one half the magnitude of the load resistance of the blast resistant glazing.

b.      1.0 times the magnitude of the load resistance of the blast resistant glazing if the maximum air blast pressure is less than one half the magnitude of the load resistance of the blast resistant glazing.

 Currently, UFC 4-010-01 (2007 revision) references ASTM F2248-03 and not the more up-to-date F2248-09 edition.  It is our understanding that ASTM F2248-09 is not required in the design of blast resistant systems until referenced in the most current version of the UFC which is anticipated this year or early next year.

The changes may be difficult to accommodate with static equivalent analysis and may require a larger push for dynamic blast analysis to maintain reasonable connections.

Written by Matt Quinlivan, E.I.T.

Be Careful With Manufacture Storefront Design Charts

Design wind load charts put out by manufactures are usually only good for estimating overall span deflection of a mullion, and do not typically consider proper methods for stress design.

The 2010 Aluminum Code has new criteria for considering the unbraced length of open sections. The unbraced length for a vertical mullion is usually considered to be the distance between horizontal mullions. However, design wind load charts put out by many manufactures of storefront systems are often based on the assumption that the mullion has full lateral buckling support and an unbraced length of zero. How can this be?

I believe that the manufacturers are considering lateral bracing from the glass and the mechanical gaskets. However, after review of many industry specs it is clear that mechanical gaskets should not be considered as a means of lateral bracing for open shaped storefront mullions. Therefore, the charts error on the side of being too liberal. When it comes to the calculations, they can’t match up and the mullions usually don’t perform as well as the charts indicate.

Unfortunately, it’s in the interest of the manufactures to keep the charts the same because they are competing against one another for framing systems with the highest performance standards.

Glaziers should keep this in mind when selecting open shaped vertical mullions and stay well under the curve projections that are indicated. If glaziers use the charts, as is, reinforcing structural glazing or heavier mullions will likely be needed.

Automatic Sliding Doors Have Operational Limitations

It’s important for glazing contractors to get information from the automatic sliding door manufacturers, in advance, on operational limitations for their systems. 

Some automatic door manufacturers have stringent criteria on how much the supporting header and jambs can deflect from wind load and how much can be supported vertically on top of the header.

Floor Movement & Glass Railing

For interior glass railing one of the things you need to watch out for is glass railing on stairs that traverse floor levels. If the floors are designed to deflect with live load, care is needed to make sure load doesn’t transfer to the glass railing system.


We saw a project with glass railing that goes between floors and the top portion of the metal handrail continued to the second floor wall framing. There is the possibility that the second floor framing can deflect and if you have a continuous rail that goes between the second floor wall and is attached to the stair, load can be transferred into the glass causing breakage.

It’s more appropriate to break the railing at the floor transition or provide a joint that slides.

Title: Staircase Glass Railing Designs, Glass Railing, Glass Balustrade

Description: JEI offers staircase glass railing designs, glass railing, glass balustrade and glass railing calculations for glazing contractors.



Kauffman Performing Arts Center - Built for snow

JEI Structural was honored to do a small part of the glazing calculations on the lower portion of this structure.    We didn't work on the roof, but we're happy to see that the Kauffman Performing Arts Center performs well with snow loads.
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