Learning Objectives
The objective of this lesson is to learn about longitudinal beam stress (BENDING AND SHEAR) and how that stress influences the design of Glulam beams.
Lecture Slides
SELF-REFLECTION SHEET FOR GLULAM BEAMS
TEST RESULTS from Monday 2/12:
Readings/Videos
I highly recommend that you also search on your own for other sources to learn more about the topic of bending stress distribution, lumber quality, and Glulam
- Glulam – class notes
- Internal bending moment of a beam: https://goo.gl/B5LCBB
- Lumber quality (start at section entitled “Softwood Lumber”): https://goo.gl/UWFDvo
- Standard Glulam beam layups: https://goo.gl/R4XN7f
- Chapter 6. Breyer, Donald E., Fridley, Kenneth J., Pollock, Jr., David G, and Cobeen, Kelly, Design of Wood Structure-ASD/LRFD, McGraw-Hill, 7th Edition, 2014
Answer these questions (ie. hypothesize) before coming to class
- Which is the strongest wood species: Ash, Douglas-Fir, Hemlock, or Spruce?
- Where should the strongest board be placed in a beam – top, middle, or bottom?
Activity
(Materials needed: 9 ea. of 1/2in x 2in x 24in Where sh; adhesive; gloves; plastic sheets)
5 min: (Lecture) Important wood characteristics (defects, variability)
20min: Watch beam tests (one board/species). Explain test… three point bending to measure strength. Record peak load on board for each species and discuss.
30min: (Exercise) Four species glulam fabrication
Each team picks the strongest looking board from a bin of one species, then moves to the next bin to pick the strongest looking board of the next species and so on.
Each team designs and glues together a four-layer glulam for testing on Wednesday.
The team with the strongest glulam wins a prize.