Atch 2. FEBR_Blast_Test Frame Design_Consideration Guidance.pdf

Design and Installation Considerations for DS/PSD/RD Forced Entry and Ballistic

Resistant (FE/BR) Glazings, Blast-Resistant Glazings, and Test Fixtures

Years of testing glazings has yielded some basic considerations based upon lessons learned. This document is intended to provide general observations that can be adapted as required to aid in the successful and efficient execution of glazing testing and evaluation. This document does not provide specific guidance but is intended to give the performer of such test issues to consider when planning for and executing glazing evaluations.

There are various standards and tolerance references that are published for plate and laminated glass that will assist a vendor in determining the tolerances needed for designing a framing system for typical Blast and FE/BR glazings. They include:

• ASTM C1036-16: Standard Specification of Flat Glass

• ASTM C1048-18: Standard Specification for Heat-Strengthened and Fully Tempered Flat

Glass

• ASTM C1172-19: Standard Specification for Laminated Architectural Flat Glass

• ASTM C1349-17: Standard Specification for Laminated Architectural Flat Glass Clad

Polycarbonate

Some highlights are that the average Blast and FE/BR glazing that will meet the Department’s

FE/BR desired protection:

• Weight around 25lbs to 30lbs per square foot.

• General laminate compositions consist of o Threat Face: two to three ply laminated glass on o Air Gap: 3/8” to 1/2”

▪ Some glazing configurations may feature multiple air gaps o Protected Face: two to four ply laminated glass o Anti-Spall Layer

• Thickness tolerances for monolithic glass are:

• Length and width tolerances for glass clad polycarbonates:

o Two- or three-ply tolerances are ±1/8” o 4 or more ply tolerances are ±3/16”

• Length and width tolerances for laminated glass:

o If the interlayer is greater less than 1/4” then the tolerances are +7/32” to -3/32” o If the interlayer is greater than 1/4” and less than 1/2” then the tolerances are +1/4” to -1/8” o If the interlayer is greater than 1/2” and less than 1” then the tolerances are +1/4” to -1/8”

Importance:

All the above reflects that a vendor designing a framing system to hold a Blast or FE/BR laminate for Forced Entry, Ballistic, or Blast testing must account for the variations in the laminate thickness and height/width to ensure their test frame can account for variations in the test samples. A vendor must also understand the weight associated with handling the test samples and have a plan how to mount the laminates in the test frame without breaking the glass and achieving the correct bite dimensions.

Example:

A 48” x 48” FE/BR/Blast layup with 3-plys of glass / 1/2” airgap / 3-plys of glass could weight

400lbs to 480lbs, and have an actual size of 47-3/4” x 47-3/4” to 48-1/2” x 48-1/2” This accounts for the protected side 3-ply laminate being +1/4” to -1/8” off, and having the threat side 3-ply laminate being +1/4” to -1/8” off, with a sloppily put together airgap. Of course, this is an extreme and most likely the laminates will be balanced over the airgap but that still leaves a +1/4” to -1/8” total variation.

Advice to Enable Smooth Installation:

It is advised that test frames be constructed allowing for a 1/2” mounting gap in addition to the required glass bite in all directions, and a variety of setting block thicknesses available on site to ensure a snug fit and the correct bite size. Additionally, it is advised to use an industrial glass vacuum lifter, of appropriate capacity, to install the test articles into the frame to avoid damaging the glass during installation.

Be aware that depending on the particular specification and weight of the glazing unit, a vacuum lifter may not be applied to the spall film on the protected face. When planning for test arena setup, consideration should be given to test frame assembly. This may require a sufficient work area on both the protected side and threat side of the glass (i.e. concrete work area for lifts or heavy equipment and rigging onsite).

Generally, the test glazing is held in place using two steel or aluminum angle sections nested together to simulate a window frame:

Figure 1: Example of Typical Test Frame Assembly

This configuration makes glazing installation difficult from the threat (exterior) side of the laminate or may require additional assembly. It is recommended that careful planning be done early in the design process for the test fixture.

Test fixture design and fabrication must account for the glazing tolerances mentioned above in this document. The test fixture may need to accommodate many test specimens during a project and thusly must be fabricated to very exact tolerance for level, plumb, and squareness

(better than normal construction tolerances) to ensure adequate clearance for efficient assembly.

Special care must be taken in handling and installation of glazing units. Generally, the glazing unit should be isolated from hard surfaces or sharp items using setting blocks, gaskets and the like. Under no circumstances should there be any prying or manipulating of glazing units with common tools unless special protective measures are taken to avoid cracking or damaging the units or any component thereof.