TM 5-840-2
c. Roof live loads. Minimum roof live loads of
design uniform live snow load may be made.
f. Wind loads. Structures should be designed
98kg/m (20 psf) will be considered for construction
and maintenance load roof. Reduction of roof live
for wind loads in accordance with TM 5-809-1.
loads will be permitted based on tributary loaded
Design factors shall assume that the wind can come
area and roof slope on any structural member in
from any direction and that negative pressures
accordance with TM 5-809-1. This reduction will
(suction forces) act on roofs, eaves, cornices, and
apply only to supporting structural members.
walls facing the opposite to the direction of the
d. Overhead cranes. For maneuvering large
wind. Exposure "A" should not be used in the
items in storage warehouses, overhead cranes pro-
design of warehouses in military installations.
g. Seismic loads. Seismic design of warehouses
vide mobility without occupying excess storage
space for material access. The beams and/or col-
shall be in accordance with the provisions of TM 5-
umns supporting the overhead crane must be
809-10/NAVFAC P-355/AFM 88-3, Chap. 13.
designed to compensate the additional loads im-
Certain warehouse storage areas are considered
posed.
high risk or essential facilities where damage to the
(1) Impact loads. Increases in design loads for
structure could cause particular hardship or danger
impact include a vertical force equal to 25 percent
to life. These structures include flammable storage
of the maximum wheel load, a lateral force equal to
areas and chemical storage areas. In designing for
20 percent of the mass (weight) of the trolley and
horizontal seismic loads, these types of structures
lifted load only applied one half at the top of each
should be designed with appropriate occupancy
rail, and a longitudinal force of 10 percent of the
importance coefficients as detailed in TM 5-809-
maximum wheel load of the crane, applied at the
10.
top of the crane rail (TM 5-809-1).
2-3. Floor types.
(2) Moving loads. Support increases for mov-
ing loads are beams-100 percent, columns 80
Warehouse floors are constantly subjected to
percent, and foundations, footings and piers -- 40
heavy-duty usage; consequently proper floor types
percent (NAVFAC DM-2).
are an important consideration in design. Each type
e. Snow loads. The snow load design require-
has its particular characteristics and is best suited
ments shall be in accordance with TM 5-809-1.
for a particular type of traffic. General warehouse
Design considerations shall include the exposure
space should be floored with a concrete slab of
and slope of the roof and its geometric and thermal
proper design to carry the wheel loads and
features. For a roof with a slope less than 40 mm
withstand the abrasion generated by the continual
per meter (0.04:1) ( inch per foot) a surcharge of
use of forklift trucks. The constant travel by forklift
8 kg/m2 (5 psf) as recommended by ANSI A58.1,
trucks can deteriorate an unprotected concrete
should be added to the calculated snow load for
surface, causing dusting and breakdown of the
rain on snow. Since warehouses in general have
surface. Hardeners and dust proofers are rec-
large roof areas, it is recommended to include this
ommended to alleviate this problem: they not only
surcharge in the roof design. If the warehouse
keep down the dust but they generally provide a
being designed is to be an unheated structure, the
reflective surface that will aid in more even
snow load will most likely be heavier than for a
distribution of lighting. Surfaces that are subject to
heated structure because of lack of snow melt. The
wetting, such as outdoor docks, should not have a
aforementioned are uniform snow loads for flat
smooth finish to the concrete since this is a safety
roofs. If the roof is sloped, a reduction in the
2-3
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