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INSPECTION - Aluminum Platform Design
I. Purpose of
At the request of the Client, we have
structural analysis of the 4'x4' platform
as described in the specification,
by the Client. The scope of this
preliminary report includes checking the
design for 80 psf floor live load, and
the handrail for Code prescribed forces
50 lb/ft (uniform load) / 200 lb (point
II. Description of Platform:
The platform consists of nominally 4 ft.
square segments, which are to be
end to end, in order to form a continuous
walkway approximately 18" above the
ground surface. Each segment has 4 legs
which bear upon the ground. Handrails
are continuous along 2 opposite edges.
Materials are 6061-T6 aluminum structural
shapes and extrusions. Decking (by
others) is to be 2x6 High Density
(HDPE) by US Plastic Lumber
The various structural members were
analyzed for the loads indicated above.
The 1" x 1" tubes and the
1.5x1.5 angles running perpendicular to
each other do not
themselves have adequate strength to
resist the 80 psf floor load. The Client
has indicated that they performed a load
test utilizing 2x6 lumber decking over
aluminum framing members, and that the
system held the load with no significant
deformation. Calculations for 1.5"
thick lumber deck boaDrs show that they
adequate strength and nearly adequate
stiffness, to span the 5 feet without the
help of the tubes and angles. In the
test, it is likely that the sub-framing
essentially as stiffeners. That is, they
helped stiffen the lumber, but the lumber
itself was stiff enough to prevent the
aluminum framing from absorbing excessive
The HDPE decking called for in the
Architectural specification, however, has
1/10th the stiffness of regular lumber.
(Reference - US Plastic Lumber published
structural properties.) Use of the HDPE
will result in nearly all the load being
transferred into the aluminum subframing,
which cannot resist the 80 psf loading.
The 4" siderail extrusion checked
out as adequate for the loading.
The members comprising the handrail are
adequate for code loadings. The U-bolt
and grade was not noted in the pdf
drawings. The required diameter likely
falls between 1/4" and 3/8",
depending on material grade.
The 2"x2" tube kickers at 45
deg. angle are necessary for adequate
stiffness and strength.
If the HDPE decking is utilized, some
sort of modification will be necessary to
the strength of the aluminum subframing.
V. Referenced Documents:
U.S. Plastic Lumber HDPE Technical Data,
- 1200 Troon
- Grand Rapids, MI
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Grand Rapids, MI 49546 Kent County