TM 5-809-6/AFM 88-3, Chap. 6
2-2. Criteria
or in an aqueous environment where contact with oxygen is
precluded. (In such situations, e.g., under washers,
a. General. For a general discussion of considerations
accelerated corrosion will occur.)
such as material selection, service life, etc., which are
(3) Climatic and temperature considerations. Special
applicable to all structures, refer to TM 5-809-2/AFM 88-3,
requirements will be considered for applications in severe
Chapter 2.
cold (minimum toughness) or elevated temperatures (reduced
b. Design loads. Design loads will be determined and
yield and tensile strength) as set forth in paragraph 2-2a.
established in accordance with TM 5-809-1/AFM 88-3,
(4) Abrasive wear. Additional thickness will be
Chapter 1, or MIL-HDBK-1002/2 except where provided
provided in locations subject to abrasive wear, and use of
otherwise by this manual or other established standard
replaceable wear plates for severe conditions will be con-
applicable to the type of structure under consideration.
sidered.
Seismic loading will be in accordance with TM 5-809-
e. Timber materials. Design requirements for timber
10/NAVFAC P-355/AFM 88-3, Chapter 13. Loadings not
materials will be in accordance with paragraph 2-2a.
covered by the criteria in this manual will be obtained from
f. Aluminum materials. Design requirements for
available technical literature, manufacturer*s brochures, or
aluminum materials will be in accordance with paragraph 2-
will be carefully formulated. In case of any conflict between
2a.
criteria and available data, the most current acceptable data
g. Composite construction. Composite construction in-
or practice will be used. Particular attention will be given to
cludes construction such as cast-in-place concrete bonded or
wind, seismic, dynamic, and fatigue loads on cable-
connected to precast members, cast-in-place concrete bonded
supported structures and other similar force-oscillating
or connected to structural timber, sandwich panels having
structures.
relatively stiff and strong facings bonded to lightweight cores
c. Design stresses. Allowable stresses or load factors
of lesser strength, such as concrete over rigid insulation, etc.
applicable to the various materials which may be used will
Composite construction has applicability to certain types of
conform to TM 5-809-2/AFM 88-3, Chapter 2, unless
structures as covered in MIL-HDBK-1002/6. Composite
indicated otherwise by paragraph 2-2d.
construction also includes cast-in-place concrete used in
d. Design requirements. Designs will conform to the
conjunction with structural steel or metal decking. Design
general concepts and practices of the proper design
guidance for these types of composite construction is given
specification listed in this manual. Where the design of a
in MIL-HDBK-1002/3. Applicable references for composite
particular structure or of a special case is not covered, the
construction are ACI 318, Chapter 17; PCI MNL-120 and
design approach and technical formulas will be based on
PCI MNL-126; American Association of State Highway and
available technical literature or will be carefully formulated.
Transportation Officials (AASHTO) Standard Specifications
Wherever possible, standard, easy-to-get materials will be
for Highway Bridges; National Forest Products Association
specified. New materials, units, and systems of a progressive
National Design Specification for Wood Construction
nature or creative design concepts that are economically and
(timber portion) and ACI 318 (concrete portion); and
structurally sound may be considered. In all cases, the design
American Institute of Timber Construction (AITC) Timber
method, structural framing system, and materials will be the
Design Handbook (2nd Edition, 1974, covers past practice
most economical, effective, and efficient from the
-- not covered in current edition). The combined action of
standpoints of the structure*s initial and maintenance costs
flexible and rigid shear connectors will not be considered as
and its design life. If there are conflicts among the criteria
providing simultaneous shear transfer. Rigid connectors
given in this manual for a specific type of structure, the most
include roughened and adhered surfaces and structural
conservative design method will be used. This will not
shapes. Flexible connectors include items such as bolts,
preclude, however, the use of new codes or specifications
stirrups, dowel bars, and ties.
which, although less conservative, are considered acceptable
h. Composites and structural plastics. Composites and
for military construction.
structural plastics have limited applicability to military
e. Design details.
construction and then only to selected specialty structures.
Composites and structural plastics will be used only when
provided for the following conditions or locations:
approved by the appropriate headquarters. Among the
(a) All structural surfaces exposed to weather will be
concerns associated with structural plastics are fire resistance
sloped to drain.
characteristics and properties which generally do not
(b) Intersecting surfaces forming valleys or pockets
conform to military fire protection criteria. Precautions will
that may retain water will be arranged to provide drainage.
be observed when using composites and structural plastics
(c) Structural steel and wood members will be
in recognition of their unfavorable fire resistance properties.
designed so they will not retain moisture or, when in pairs or
multiples, so water or moisture will not be held between
members.
2-2
Previous Page
