Gusset Plates

How many different kinds of structural connections can you spot?

Learning Objectives

After completing this lesson, the student will be able to strengthen a structure drawing inspiration from biological systems.

Standards

  • NGSS HS-ETS1-2
  • CCSS.Math.Practice.MP1
  • CCSS.Math.Practice.MP4

Supplies

  • Ruler
  • Balsa wood sticks
  • Balsa wood sheets
  • Pins
  • Wood glue
  • Knife (see teacher or parent)
  • Spring balance
  • Bubble level
  • Bridge you built in the lesson called trusses
  • Safety glasses

Units Used

  • Force: Newton (N) (1 N=1 kg m/s2)

Strengthen Your Bridge 

What sort of connections did you find on your nature walk?  I suspect you often found some type of central support to help transfer load.  For example, an ant’s legs do not connect directly to each other, but instead join at its body, which helps support the entirety of the structure.  In engineering the equivalent to this is a gusset plate.  Gusset plates are what you see the various members of a truss connected too.  Can you find the gusset plates in the picture at the top of this lesson?

Gusset plates help transfer load and add strength.  To see this for yourself, pull out the bridge that you built in the lesson on trusses.  Build a second one with gusset plates using the balsa wood sheets in your kit.  Cutting a small square of balsa wood sheet will work as a gusset plate for this bridge.  You may find a combination of pins and wood glue to be optimal for securing your bridge.  

Let’s see which one is stronger, this is the fun part – time to put on your safety glasses.  Set both bridges up covering a similar span.  Start adding weight to each of them until they break.  Which one held longer?

Fishy Analogue

A fishy analogue to a bridge’s gusset plates could be the hypural plate that helps join the fish’s spine to its tail.  Using the balsa wood components you have, devise your own fish tail structure.  How would you connect this tail to your BLIMP hulls?

Hubert Ludwig, Public domain, via Wikimedia Commons

Next Steps

From here, if you’re interested in learning more about trusses, you can hop to an intermediate level lesson on Truss Analysis that will exercise your math skills. If you prefer to focus on concepts, check out the lesson on Thin-Walled Structures.

A Day in the Life
Form and Function
Balance
Movement
The Literate Engineer

Last updated: November 23, 2022.