Volume 46, Issue 8 - September 2011

feature

PROTECTIVE GLAZING
CONTINUES TO ADVANCE

As Government Projects Keep Contractors Busy, More Glass Companies Enter the Protective Glazing Fray

By Megan Headley

In the ten years since September 11, 2001, citizens of and visitors to the United States have grown accustomed to a world of heightened security. By 2003, when Sandia National Laboratory released the report Assessment, Development and Testing of Glass for Blast Environments, the glass industry knew that protective glazing could play an important role in protecting building occupants from all manner of threats.

The report stated: “Evidence that hardened windows can protect personnel is provided by the performance of the new windows in the renovated section of the Pentagon when it was struck by an airplane on September 11, 2001. Recently completed retrofits to the structure included installing thermally tempered and laminated windows designed for blast-resistance. Many of these windows did not fail even when they were exposed to the aircraft fuel fireball, thereby preventing fire from entering many of the offices around the crash location.”

From there, the demand for protective glazing products grew. Just as importantly, the demand has remained relatively steady in the last two years as government funding has kept afloat the construction schedules of federal buildings, military bases and other government projects while commercial and residential construction waned. As a result, protective glazing products have moved from a highly specialized niche to a demand everyone in the glass industry is looking to supply.

Everybody’s Doing It
No doubt about it, protective glazing is a hot spot right now.

“In the last ten years I’d say the biggest change in protective glazing and custom applications of it have become the majority of the work that we do,” says Gantt Miller, chief executive officer of Winco Window in St. Louis.

As more manufacturers begin producing these products, glazing contractors are lining up to put them in.

Stewart P. Jeske, P.E., president of JEI Structural in Kansas City, Mo., agrees. “There are a lot more contractors that are trying to enter into this area because that’s where a lot of the money is right now,” he says.

Today, the nation’s largest real estate developer, the General Services Administration (GSA), is putting more construction companies, and their glazing subcontractors, to work on projects requiring a level of security.

“Most of the projects have been courthouses, airports and every new or retrograded government installation,” says Ricardo Carrillo, principal consultant with Acumen Industries in Conroe, Texas.

It’s not just the U.S. government, points out Vic Cornellier, president of TSI Exterior Wall Systems in Landover, Md. “It’s every government, so embassies, consulate offices, private developers even that might have a building full of defense contractors. If government representatives are going to be in those buildings, then they have to have a blast regulation also,” he says.

As demand grows, so too do the number of contractors and fabricators working with these materials.

Breaking Out of the Mold
Cornellier recalls installing blast jobs 15 years ago, when Norshield in Montgomery, Ala., was about the only supplier of those products.

Back then, Cornellier recalls, “Each government agency was developing its own criteria and they weren’t communicating, like [they had] trade secrets. Then GSA … standardized blast performance. But there are still agencies that work independent of that.”

Greg Galloway, product marketing manager for YKK Architectural Products in Austell, Ga., explains that today, “There are two main organizations that provide standards and job specifications. GSA manages more than 9,000 government buildings and uses GSA TS01-2003 [GSA-TS01-2003 is the test standard used by GSA and other agencies using the Interagency Security Committee’s (ISC) Security Design Criteria]. The Department of Defense (DOD) promulgated the United Facilities Criteria (see “Future Changes Coming to UFC, ASTM F2248 Standard” in the box below). It is a prescriptive standard built specifically around the use of polyvinyl butyral (PVB) as the interlayer.” He notes, “DOD administers requirements for military bases and they tend to rely more heavily on controlled perimeters: fences and people with guns at checkpoints.”

These regulations, Cornellier says, formed the start of the blast industry. With standards in place, new companies began to enter the fray. “Usually the commodity [suppliers], have products that meet the low level of blast, so at least they’ve got their foot into the door.”

Future Changes Coming to UFC
by Matt Quinlivan


For the past several years, the Unified Facilities Criteria (UFC 4-010-01) has been the governing code for all U.S. Department of Defense (DOD) blast mitigation projects. Referencing ASTM F2248-03, Standard Practice For Specifying An Equivalent 3-Second Duration Design Loading For Blast Resistant Glazing Fabricated With Laminated Glass, 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, Standard Practice For Determining Load Resistance Of Glass In Buildings, 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 currently is undergoing revisions that should clarify blast design loads and reference a more stringent version of the ASTM F2248 standard—ASTM F2248-09. 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 (the 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 before the end of this 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.

Matt Quinlivan, E.I.T., is an engineer
with JEI Structural Engineering. This article is reprinted courtesy of JEI Structural Engineering.


“Ten years ago it was a lot more cookie cutter,” Miller agrees. Today, suppliers looking to stand out may move to more custom systems.

But challenges, of course, face glass fabricators and especially installers jumping into this specialized arena.

“A lot of time the glazing contractors are not very informed on these [protective glazing] issues, and so when-
ever they bid these [projects] they may not know what to look for in the specifications,” Jeske says. “They end up getting burned on the back end.”

For example, Jeske sees, “they’re supposed to submit calculations on down the road and, a lot of times, they haven’t been thoroughly educated in the specs what to look for … Or they don’t understand that it requires three times the amount of anchors that they were originally thinking about, or that the system that was originally tested under blast loads does not really meet the requirements that were specified. So they get into a lot of messes that way.”

Cornellier has worked on enough projects with blast requirements to know that they take a lot more time, a lot more money and a lot more experience than non-blast projects.

Walking through the process, he explains, “You end up having to design to calculations based upon requirements that are set forth in the specifications. Then the owners, be it the government or individual companies, hire a blast consultant. They give you design criteria and then you have to submit calculations that show that you’re meeting that design criteria.” From there, “All the data is interpreted: you have to understand what the intent of the design is, then you have to interpret it, then you submit your interpretation, and they tell you whether you got it right or you got it wrong.”

Cornellier says he sees as much as 75-percent additional time spent on engineering and submittals for these projects compared to non-blast.

Carrillo agrees that the calculations required often pose a problem—but in a different way. He recalls bidding a government project where the specification required a specific tool for analyzing the effects of blast/dynamic forces upon glazing. “It utilized information other than the traditional equivalent static forces methods employed by most consulting engineering firms to design safety and blast resistance glazing.” Problem was, he found, access wasn’t granted “unless you were already a government-approved contractor.”

As the market segment grows, more resources are becoming available to help glazing contractors and their
customers (see below).


More Information
In 2010, the Glass Association of North America and Protective Glazing Council International published a joint Protective Glazing Manual, which incorporates a history of the protective glazing products including films, interlayers and glass. The manual goes into depth to describe typical applications (ballistics, blast, hurricane/seismic, security, etc.) and pertinent information on testing standards and building codes. Both organizations have published documents for download on their websites, www.glasswebsite.com and www.protectiveglazing.org.

Product Evolution
Valerie Block, senior marketing specialist with DuPont Glass Laminating Solutions based in Wilmington, Del., notes that while building codes have not adopted security glazing requirements that address terrorism, an increasing number of architects on government and many high profile commercial projects are including blast requirements in their architectural specifications. “This has prompted manufacturers to test and market blast-resistant doors, windows, storefront and curtainwall systems that incorporate laminated glass,” Block says. “Last year we sponsored several rounds of shock tube and arena testing to evaluate glazing systems made with PVB and ionoplast interlayers. Both interlayers are effective in reducing flying glass fragments, a potential cause of injury after a blast event.”

Julia Schimmelpenningh, global applications manager of architectural, advanced interlayers for Solutia Inc. in Springfield, Mass., has likewise seen interest in protective interlayers.

“With the terrorist attacks there was a huge interest peak in the desire for bomb blast protection,” Schimmelpenningh says. “Many door and window companies restructured or adapted their framing systems to handle the common loads that would be placed on them based on the typical blast loads being used. This represented a large amount of interest in laminated glass and the awareness that common ¼-inch laminated glass with 0.030-inch or greater interlayer thickness offered a tremendous level of protection.”

In recent years, Galloway has found that designers specifying blast performance are looking for increasingly stronger levels of protection.

“[We] do an increasing number of blast projects,” he says. “Until the last couple of years, most projects specified a 3b level of performance [ISC’s “high” protection level; see “ISC Security Criteria Glazing Performance Conditions” - see below]. That is, after the blast test, fragments of glass are allowed up to 10 feet away from the test specimen. This can be achieved with PVB as the interlayer.”

Today, Galloway says, “We are seeing an increasing number of specifications asking for a level 2 [ISC’s “very high” protection level].”

Bundled Performance
As with the protective products being sold in hurricane zones (see July 2011 USGlass, page 22), designers of government buildings are looking for more than protection from attack. They’re looking for a work environment with natural light and that also performs efficiently.

“Since 9/11, the glass and protective window/protective fenestration industry have significantly advanced the quality and performance of extreme load and ballistic-resistant products. Key to this has been the development of protective product systems that also provide energy efficiency in architecturally acceptable packages,” says Joseph L. Smith, PSP, principal engineer, director and senior vice president of Applied Research Associates, an engineering and research company in Albuquerque. “Physical testing, coupled with more advanced high fidelity analytic modeling, has allowed for the
use of lighter, more efficient and cost-effective design solutions.”

Schimmelpenningh agrees that when safety glazing is needed, architects, designers and building owners are now looking for bundled performance options, “meaning safety and security as well as energy and sound control,” she says. “As the awareness has grown over the decade, the products have evolved with options to meet most needs. It’s the willingness to incorporate these options at the build, making them part of the initial performance requirements and building use concepts, that have changed most,” she adds. However, performance can lead to challenges for fabricators.

Companies entering this evolving market segment are sure to find additional challenges of their own.



 

Megan Headley is the editor of USGlass




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