What Causes Bridges to Collapse?

Learning Which Shapes are Strong

​A lesson in engineering.  Using popsicle sticks and glue, teams designed and built bridges that were entered in the APEG BC (Association of Professional Engineers and Geoscientists of BC) competition at Douglas College over the weekend.  

​The students learned that triangles are stronger than other shapes, and that challenging your design is the way to make advancements in the design.  

Each bridge was loaded with a rig that measured the number of newtons of pressure that could be applied to the bridge deck before collapsing.  Students then had feedback on how their design could have been stronger.  

​Tips included narrowing the width of the bridge, changing the orientation of the sticks on the bridge deck, mounting the bridge decks through the triangle of the truss, and using more glue!!

Sampling of Bridges at the Competition

Lessons

• Engineering is a process, where you build things then see how much they can sustain.  
• Destroying your creation is part of engineering, as you measure how much it withstands, and learn from it, in the process of destroying it.

• In general, the sides of our bridges were very strong.  The triangle design was good. The bridge decks were the points of failure.
• Some factors that break structures are weight, moisture, temperature, wind, gravity ...
• In this case, we applied direct pressure to the bridges to see each one's 'point of failure'.  This is the spot with the greatest weakness toward the pressure.