SCOPE AND RELATED CRITERIA.
a. Scope. This section contains design criteria and procedures for
solid steel and built-up blast doors. A good portion of the analytical
procedures have been described earlier in this manual. Illustrative
examples are provided for both the solid steel and built-up blast door.
b. Related Criteria. Current design criteria and procedures are
contained in the following reports: Design of Steel Structures to Resist
the Effects of HE Explosions by John J. Healey, et al., and Structures to
Resist the Effects of Accidental Explosions, NAVFAC P-397. Experimental
data on the behavior of steel doors under blast loading was collected
during the ESKIMO Magazine Separation Test Series. The deformation
criteria for structural steel elements and plates outlined in paragraph
1.b. of Section 4 in this manual also apply to both solid steel and
built-up blast doors.
2. GENERAL. Blast doors can be divided into two categories depending on
their use. They may be required to seal off openings from blast pressures
(which is their primary use), or they may be required to resist primary
fragment impact. Blast door exposure to fragment impact is a function of
the door orientation to the source of an explosion and the nature of the
donor system. Procedures for predicting the characteristics of primary
fragments (such as impact velocity and size of fragment) are presented in
NAVFAC P-397 and also in the report by John J. Healey, et al., Primary
Fragment Characteristics and Impact Effects on Protective Barriers.
Paragraph 11 of Section 2 of this manual also provides some information on
this subject. Blast doors may also be grouped based on their method of
opening, such as a) single-leaf, b) double-leaf, c) vertical lift, and
d) horizontal sliding.
3. DESIGN CONSIDERATIONS. The results of the ESKIMO Test Series indicate
that most blast doors fail because the door frame cannot transfer the shear
on the door to the surrounding wall. As a result, the door remains intact
and the force of the explosion shears the door casing and blows the door
through the wall. As stated in Class Notes by Keenan, the ultimate
resistance of the door must be tailored to the strength in shear of the
door casing. Doors usually fail in rebound also, though they may be able to
withstand the blast loading. It is imperative, therefore, that the door be
designed for the rebound phase, keeping in mind that rebound forces are
greater if the door remains elastic. On certain occasions, it may be
required of the door to fail in rebound and in such cases, the door hinges
have to be designed accordingly.
TYPES OF CONSTRUCTION.
a. General. The two basic types of blast door construction are solid
steel plate and built-up doors. The choice of either a solid steel door
or a built-up door must be based upon comparison of their relative economy,
considering the particular blast pressure and fragment environment, size
of door opening, strength of the door casing and boundary conditions of the
door. Solid steel doors are used usually for high pressure ranges (50 psi
or greater) and where fragment impact is critical. For low pressure ranges
(10 psi or less) where fragment impact is not critical, the use of built-up
doors is a practical arrangement.