Figure 46. Joist contruction
carry only the weight of cargo. For this reason, we will
discuss the different types of foundations and how they
you should use a heavier joist rather than narrow the
should be constructed to adequately support the intended
spacing. When joists are being placed, make sure that
the greatest bearing surface is used. In other words, place
Normally, loading dock
them with the crown edge up.
foundations are constructed of either wood and masonry
Placing the crown edge up will tend to counteract the
piers or columns. These columns or piers must be spaced
bending force imposed on the joist. After each joist is
according to the weight they are to carry. In most cases,
placed, it should be secured. as indicated in figure 46.
however, they are spaced from 6 to 10 feet apart.
If we expect loading docks to
7-4. If the earth on which the foundation is to rest
adequately support the loads placed up on them and to
has low supporting strength. of if the loads are expected
withstand the abuse from vehicles, we must reinforce
to be extremely heavy, the foundation should be
them with some type of bracing.
constructed as a solid, reinforced concrete wall.
This bracing must be properly designed and placed to
7-5. Sills. Sills consist of single heavy timbers or
give the support desired.
buildups of two or more timbers. Sill sizes will be
7-9. If wooden piers are used as a foundation, they
determined by the intended loads to be carried and the
should be braced to each other with diagonal braces, as
distance between piers. Consequently, sills are used with
shown 'in figure 45. If wooden girders are used in the
pier type foundations and are placed directly on the pier.
platform construction, a truss brace should be placed
If sills are correctly placed, they will surround the
under each girder.
If the platform is to support
perimeter of the dock. After the sills are tied to the
extremely heavy loads.
piers, girders (if needed) are placed.
bracing should be secured with bolts. On the other hand,
7-6. Girders. Girders are used as interior foundation
light load carrying platform bracing may be secured with
walls to support the inner ends of floor joists. However,
spikes. No matter what method you use to secure the
they will not be needed if joists safely span the distance
bracing, make sure that the materials used have good
from sill to sill. If girders are not used, joists should be
7-10. Decking. Decking. or flooring. used on loading
placed directly on the sills.
7-7. Joists. Joists are the lighter pieces which make
docks should be at least 3 inches thick and laid
up the body of the floor fame. We don't mean that they
perpendicular to the joists. All joints must be staggered
are actually light in weight but that they are light in
and joined directly over a joist. After decking has been
comparison with the other framing members. Joists are
correctly fitted and placed, it should be secured with large
usually 3 inches thick, but thicknesses will vary to suit the
construction details. They are usually spaced from 16 to
7-11. After the platform has been erected and properly
24 inches on-center. However, if this spacing is too wide
floored, it should be protected from unnecessary bumps
to support the intended load.
and scrapes. This protection is supplied by fender boards.
7-12. Fender boards. Fender boards are heavy timbers
placed in front of the loading dock to protect it from
vehicle contact damage. They are secured to the sills
with spikes or bolts, depending upon the size of the
timbers. If adequately placed, fender boards form a solid,
continuous row of timbers.
7-13. General Maintenance Problems. Your job is
not complete when you finish the construction of the
warehouse loading dock.
There is a continual
maintenance problem, and it is your job to perform this
maintenance. Aside from original flaws in materials,
structural sealing, weathering, and normal wear and tear,
rust (chemical action), and insects (termites and marine
7-14. Decay and its prevention. Unpainted or untreated
wooden members are more subject to decay than any of
the other construction materials. Warm, humid climates
or seasonal periods