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Beams

9.4.1 Describe a beam.

Beams are structural members that are subject to loads acting normally to their longitudinal axis. The loads create shear stresses and bending moments and cause the beam to bend or flex. Beams are classified according to the way they are supported; for example, cantilever beams are rigidly supported at one end with the other end free.
  • Wikipeadia reference with some examples.
  • makingthemodernworld.org on bridges and beams.

9.4.2 Describe how beams are designed to transfer forces and distribute loads through the beams.

9.4.3 Describe the historical development of the materials used to manufacture beams.

Solid wood beams—high bulk. Concrete beams with metal. Metal sectional beams. Reduction in the amount of material in the beam.


Roof beams of solid timber Concrete reinforced beams with corrosion Metal section beams

9.4.4 Identify a variety of shapes for sectional members of a structure.

Consider rectangular, circular, L-shaped, I-shaped, castle-shaped.

9.4.5 Describe how the shape of sectional members of a structure makes the most effective and economic use of materials.

They allow the use of less materials and still carry the load without failing. Less materials therefore less total cost of members/beams.

9.4.6 Explain that sectional members of a structure may be manufactured in sheet material.

For example, laminated veneer lumber (LVL).

9.4.7 Outline the benefits of using LVL beams in the construction industry.

LVL is used in place of more expensive wooden beams where the finished product is hidden by other forms of cladding (siding).

House with timber cladding

9.4.8 Explain the importance of factor of safety in the design of beams.

The factor of safety is essential and must be added to any structure (past the known internal and external forces that will be acting on the structure) for any unpredicted forces that would otherwise cause stress or strain on the structure.
  • A NASA blog on Factor of Safety.
  • Another Blog, interesting tid-bit about transport factor of safety.
After the National Transportation Safety Board announced that under-designed gusset plates were a factor in the collapse of the Interstate 35W bridge, Gov. Tim Pawlenty ordered inspection of 23 high truss bridges on the state highway system. Photo by David Gonzalez

References

Bulleted list and italicised paragraphs are excerpted from Design Technology: guide. Cardiff Wales, UK: International Baccalaureate Organization, 2007.

Images are clickable links to its location.

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Page last modified on January 16, 2014, at 06:02 PM