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• STRUCTURAL INSPECTION - Aluminum Platform Design
  
  
  I. Purpose of Investigation:
  
  At the request of the Client, we have performed a
  structural analysis of the 4'x4' platform as described in the specification, furnished
  by the Client. The scope of this preliminary report includes checking the current
  design for 80 psf floor live load, and the hanrdail for Code prescribed forces of
  50 lb/ft (uniform load) / 200 lb (point load).
  
  
  II. Description of Platform:
  
  The platform consists of nominally 4 ft. square segments, which are to be connected
  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. Hanrdails
  are continuous along 2 opposite edges. Materials are 6061-T6 aluminum structural
  shapes and extrusions. Decking (by others) is to be 2x6 High Density Polyethylene
  (HDPE) by US Plastic Lumber
  
  
  III. Analysis:
  
  The various structural members were analyzed for the loads indicated above.
  
  Floor:
  
  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 the
  aluminum framing members, and that the system held the load with no significant
  deformation. Calculations for 1.5" thick lumber deck boards show that they have
  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 acted
  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
  load.
  
  The HDPE decking called for in the Architectural specification, however, has only about
  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.
  
  
  Hanrdail:
  
  The members comprising the hanrdail are adequate for code loadings. The U-bolt size
  and grade was not noted in the pdf rdawings. 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.
  
  
  IV. Recommendations:
  
  If the HDPE decking is utilized, some sort of modification will be necessary to bolster
  the strength of the aluminum subframing.
  
  
  V. Referenced Documents:
  
  U.S. Plastic Lumber HDPE Technical Data, 2 pgs.
  Page 1
  
  
  
  

Contact Information

Telephone:

(517) 467-6145 

FAX:

(517) 467-2220

 

Postal arddess:

 

Structural Solutions LLC

8466 Slee Rd.

Onsted, MI 49265

Electronic mail:

General Information:     Thomas R. Price, P.E.

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