FEMA 453 Design Guidance for Shelters and Safe Rooms

Rigid catch bar systems were designed and tested as a means of
increasing the effectiveness of filmed and laminated window upgrades.
Anti-shatter film and laminated glazing are designed to
hold the glass shards together as the window is damaged; however,
unless the window frames and attachments are upgraded as well to
withstand the capacity of the glazing, this retrofit will not prevent
the entire sheet from flying free of the window frames. The rigid
catch bars intercept the filmed or laminated glass and disrupt their
flight; however, they are limited in their effectiveness, tending to
break the dislodged façade materials into smaller projectiles.
Rigid catch systems collect huge forces upon impact and require
considerable anchorage into a very substantial structure to prevent
failure. If either the attachments or the supporting structure
are incapable of restraining the forces, the catch system will be
dislodged and become part of the debris. Alternatively, the debris
Structural deSign criteria
Figure 2-
Blast curtain system
2-