Background

Civil and construction engineers are constantly faced with the problem of designing structures such as bridges, dams and towers. Sometimes these structures have failed. Bridges have collapsed, or buildings have fallen down. Our safety depends on how well engineers, draftspersons, carpenters, inspectors, and other workers do their jobs. At the same time, a structure should not be designed so that it is much stronger than it needs to be. This costs too much money.

Construction workers are faced with the same challenges that you will be facing in this activity – to build the strongest possible structure with a minimum amount of material.

Problem

Working individually or in groups of two, research, design and construct a bridge that will span a ten inch (10") space with a maximum of one inch (1") bearing surface at each end. Students must construct the bridge only with the given materials and must adhere to the project limitations. Your bridge should be light in weight yet support as much weight as possible.

• Perform research on bridge and truss design (shapes, materials, joints etc.).
• Practice Cadkey skills by drawing the bridge design.
• Apply math and science skills during efficiency calculations.
• Construct a bridge using the given materials.
• Use Modal Smart to test bridge strength.
• Recognize and test structural failures (compression, tension, torsion and shear) with model smart, research and testing.

Limitations

Only hot-melt glue may be used.
No reinforcing with pins, rods, paper clips, etc.
Use only the materials supplied to complete the project.
Substructure? 1 ¼" maximum.

Notes

Bridge Dimensions = 12" x 3" x ____ (L x W x H).
A 2 ½" hole must be left in the top for braking purposes.
Bridges can be constructed from the Cadkey drawing by placing wax paper over the drawing.
Efficiency = Failure Weight / Weight of Bridge

RESEARCH – http://www.ce.ufl.edu/activities/newtruss/

Evaluation