Composite Action

Learning Objective

The objective of this lesson is to understand what happens when layers of beams are connected to each other as opposed to when they are not connected.

Lecture Slides

Readings/Videos

I highly recommend that you also search on your own for other sources to learn more about the topic of Composite Action and shear stresses in beams.

  • UMass BCT Research Spotlight:
    https://bct.eco.umass.edu/research/research-areas/wood-concrete-composite-systems/
  • Chapter 5 of Forest Products Laboratory. 2010.Wood handbook–Wood as an engineering material.  Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 463 p.  Available on the web for free!!  http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/fplgtr113.htm
  • SpoonFeedMe video series: https://www.youtube.com/watch?v=P58ODdmCtaE

Answer these questions (ie. hypothesize) before coming to class

  1. If one board of wood bends 1 inch, how much will two boards (laid one on top of the other to double the height) bend ?
  2. How much will two boards bend if they are laid side by side?
  3. How much will two boards bend if they are nailed together?
  4. If a cement board is laid on top of the wood, will it reduce deflection?

Activity

(Materials: 2pcs of 0.75in x 2.75in x 48in Ash; 1pc of 48in long pre-drilled hardie-board; 1in long nails; worksheet to record results, and tape measures)

Working in teams of 3, students will work to fill out the following chart and then draw conclusions on their own.