Establishing Blast Criteria
- Primary use - to protect life, equipment or both.
- Door configuration - swing, horizontal slide or vertical lift.
- Opening size.
- Blast door manufacturer must provide all critical components -- door panel, frame with anchorage and hinge (swing door), blast restraints (sliding door), and hardware.
- Review wall construction - must be sufficient to withstand blast force and handle door weight.
- Review reinforcements - blast and rebound reactions will be transferred to frame and frame anchors, or blast restraints, and capable of transferring load to adjacent wall or structural sub-frame embedments.
- Type of explosive - solid, liquid or gas - ammunition, bomb, missile, chemical, nuclear, steam pressure, etc.
- Other hazards to be controlled - fire, smoke, gas fumes, ballistics, fragment resistance.
- Blast force - either PSF (pounds per square foot) or PSI (pounds per square inch).
- Static or dynamic analysis.
- Static equivalent load:
- Maximum amount of blast force the door system will be subjected to.
- Rebound - this is a negative suction phase at initial peak response and expressed as a percentage of reflected pressure (normally 100%).
- Dynamic analysis:
- Amount of blast force the door will be subjected to at Pr peak reflected pressure.
- Duration of the positive phase (stated in milliseconds - ms.)
- Rebound shall be as calculated by the blast analysis.
- Angle of incidence - if unknown, assume 0° which shall give the maximum protection.
- Maximum ductility ratio (µ) of 1 (if elastic) or greater than 1 (if plastic).
- The door edge support rotation shall not exceed ___° (degrees).
- Static equivalent load:
- Direction of initial blast force - either seating (into frame) or unseating direction (against hardware).
- Plastic or elastic deformation.
- Elastic - The allowable elastic deflection is limited to L/60, L/120 or L/240 of the span. If the doors will be subjected to repetitive blasts, then no permanent deformation shall be allowed.
- Plastic (unavailable for static design) - door system contains the blast force but allowed to deform in the opening.
- Fire Label requirements.
- Interior or exterior application.
- Door operation - manual or power operation, frequency of use, etc.
- Hardware requirements - lever handles, panic bar, access control, door closer (required for Fire Label), weatherstripping, door bottom, threshold.
Additional notes:
Use of galvanized material is not compatible with all-welded steel door construction. Hold-open devices are discouraged on a blast resistant door. When not in use, the door must remain closed at all times.