Aluminum Design Practices (and examples)
Fig. 1: Temporary Aluminum Box Truss used on a movie set
Aluminum is a lightweight metal which strength wise falls somewhere in between wood and steel (wood on average will have an allowable bending stress of 1 ksi, Aluminum is around 10 ksi for welded 6061-T6, and Steel is around 20 ksi for A36). Because of its weight, it is often used in temporary structures or during special events.
One fun fact about aluminum (fun in the sense that it is unlike any other material we’ve learned of so far, not fun in the sense that it greatly complicates the design) is the fact that once aluminum is welded it has significantly less strength than non-welded aluminum. And yes, I’m sure wood would also greatly lose it’s strength if welded to (a little joke).
Note: The most common aluminum (6061-T6) will lose about 50% of it’s strength once welded
Aluminum Analysis
How to solve for AL sections using the ADM:
- The Aluminum Allowable Stress Tables?
- Aluminum Design Rules
- Welding in Aluminum?
- Aluminum Safety Factors?
Various AL Structures:
Aluminum is used for a variety of different structural uses including:
- Stages
- Lighting Rigs
- Electrical Transmission Lines
- Windows, Doors, & Siding
- Base Ball Bats
AL Properties (english units):
- E = Modulus of Elasticity = 10,200 ksi
- G = Shear Modulus of Elasticity = 3,900 ksi
- Poisson's ratio (v) = 0.33
- Thermal deformation = 12.8 x 10-6 1/ºF
- γ = weight density = 169 pcf
Design Codes:
The 2007 version of the IBC used the 2005 version of the Aluminum Design Manual. Although the ADM has a section on welds, additional information for welding can be found in the AWS D1.2 titled “…”.