ISC/GSA Standards

Tubelite-FFBlast-Graphic01_full

This illustration shows a cross section of a test structure defining the protection levels correlated in table 1: ISC Security Design Criteria Blast Protection Levels for Windows. Table 1 describes the six defined ISC Protection Levels and the associated glazing response expectations.

The GSA and the Department of Homeland Security use a standard called the Federal Security Risk Management (FSRM) as a threat/vulnerability assessment and risk analysis to determine the protection level required for a facility.

Table 1: ISC Security Design Criteria Blast Protection Levels for Windows

 

Performance Condition Protection Level Hazard Level Description of Window Glazing Response
1 Safe None Glazing does not break. No visible damage to glazing or frame.
2 Very High None Glazing cracks but is retained by the frame. Dusting or very small fragments near sill or on floor acceptable.
3a High Very Low Glazing cracks. Fragments enter space and land on floor no further than 3.3 ft. from the window.
3b High Low Glazing cracks. Fragments enter space and land on floor no further than 10 ft. from the window.
4 Medium Medium Glazing cracks. Fragments enter space and land on floor and impact a vertical witness panel at a distance of no more than 10 ft. from the window at a height no greater than 2 ft. above the floor.
5 Low High Glazing cracks and window system fails catastrophically. Fragments enter space and land on floor and impact a vertical witness panel at a distance of no more than 10 ft. from the window at a height greater than 2 ft. above the floor.
Performance Condition Protection Level Hazard Level Description of Window Glazing Response
1 Safe None Glazing does not break. No visible damage to glazing or frame.
2 Very High None Glazing cracks but is retained by the frame. Dusting or very small fragments near sill or on floor acceptable.
3a High Very Low Glazing cracks. Fragments enter space and land on floor no further than 3.3 ft. from the window.
3b High Low Glazing cracks. Fragments enter space and land on floor no further than 10 ft. from the window.
4 Medium Medium Glazing cracks. Fragments enter space and land on floor and impact a vertical witness panel at a distance of no more than 10 ft. from the window at a height no greater than 2 ft. above the floor.
5 Low High Glazing cracks and window system fails catastrophically. Fragments enter space and land on floor and impact a vertical witness panel at a distance of no more than 10 ft. from the window at a height greater than 2 ft. above the floor.

The Department of Defense (DoD) developed a blast mitigation standard for use in designing DoD facilities, the Unified Facilities Criteria (UFC) – DoD Minimum Antiterrorism Standards for Buildings.

Table 2-1 Levels of Protection (New and Existing Buildings) and Table 2-2 Levels of Protection (Expeditionary and Temporary Structures) detail the varying levels of protection, the potential structural damage and potential injuries.

Table 2-1 Levels of Protection – New and Existing Buildings

Level of Protection Potential Building Damage /Performance Potential Door and Glazing Hazards Potential Injury
Below AT standards Severe damage. Progressive collapse likely. Space in and around damaged area will be unusable. Doors and windows will fail catastrophically and result in lethal hazards. (High hazard rating) Majority of personnel in collapse region suffer fatalities. Potential fatalities in areas outside of collapsed area likely.
Very Low Heavy damage – Onset of structural collapse, but progressive collapse is unlikely. Space in and around damaged area will be unusable. Glazing will fracture, come out of the frame, and is likely to be propelled into the building, with the potential to cause serious injuries. (Low hazard rating) Doors may be propelled into rooms, presenting serious hazards. Majority of personnel in damaged area suffer serious injuries with a potential for fatalities. Personnel in areas outside damaged area will experience minor to moderate injuries.
Low Moderate damage – Building damage will not be economically repairable. Progressive collapse will not occur. Space in and around damaged area will be unusable. Glazing will fracture, potentially come out of the frame, but at a reduced velocity, does not present a significant injury hazard. (Very low hazard rating) Doors may fail, but they will rebound out of their frames, presenting minimal hazards. Majority of personnel in damaged area suffer minor to moderate injuries with the potential for a few serious injuries, but fatalities are unlikely. Personnel in areas outside damaged areas will potentially experience a minor to moderate injuries.
Medium Minor damage – Building damage will be economically repairable. Space in and around damaged area can be used and will be fully functional after cleanup and repairs. Glazing will fracture, remain in the frame and results in a minimal hazard consisting of glass dust and slivers. (Minimal hazard rating) Doors will stay in frames, but will not be reusable. Personnel in damaged area potentially suffer minor to moderate injuries, but fatalities are unlikely. Personnel in areas outside damaged areas will potentially experience superficial injuries.
High Minimal damage. No permanent deformations. The facility will be immediately operable. Glazing will not break. (No hazard rating) Doors will be reusable. Only superficial injuries are likely.
Level of Protection Potential Building Damage /Performance Potential Door and Glazing Hazards Potential Injury
Below AT standards Severe damage. Progressive collapse likely. Space in and around damaged area will be unusable. Doors and windows will fail catastrophically and result in lethal hazards. (High hazard rating) Majority of personnel in collapse region suffer fatalities. Potential fatalities in areas outside of collapsed area likely.
Very Low Heavy damage – Onset of structural collapse, but progressive collapse is unlikely. Space in and around damaged area will be unusable. Glazing will fracture, come out of the frame, and is likely to be propelled into the building, with the potential to cause serious injuries. (Low hazard rating) Doors may be propelled into rooms, presenting serious hazards. Majority of personnel in damaged area suffer serious injuries with a potential for fatalities. Personnel in areas outside damaged area will experience minor to moderate injuries.
Low Moderate damage – Building damage will not be economically repairable. Progressive collapse will not occur. Space in and around damaged area will be unusable. Glazing will fracture, potentially come out of the frame, but at a reduced velocity, does not present a significant injury hazard. (Very low hazard rating) Doors may fail, but they will rebound out of their frames, presenting minimal hazards. Majority of personnel in damaged area suffer minor to moderate injuries with the potential for a few serious injuries, but fatalities are unlikely. Personnel in areas outside damaged areas will potentially experience a minor to moderate injuries.
Medium Minor damage – Building damage will be economically repairable. Space in and around damaged area can be used and will be fully functional after cleanup and repairs. Glazing will fracture, remain in the frame and results in a minimal hazard consisting of glass dust and slivers. (Minimal hazard rating) Doors will stay in frames, but will not be reusable. Personnel in damaged area potentially suffer minor to moderate injuries, but fatalities are unlikely. Personnel in areas outside damaged areas will potentially experience superficial injuries.
High Minimal damage. No permanent deformations. The facility will be immediately operable. Glazing will not break. (No hazard rating) Doors will be reusable. Only superficial injuries are likely.

 

Notes:1. This is not a level of protection and should never be a design goal. It only defines a realm of more severe structural response and may provide useful information in some cases. 2. For damage/performance descriptions for primary, secondary and non-structural members, refer to UFC 4-020-02, DoD Security Engineering Facilities Design Manual. 3. Glazing hazard levels are from ASTM F 1642.