This video shows the bending failure of a simply supported, Class C24 softwood beam arranged with the grain parallel to the beam axis. In this test, the specimen has a defect (or knot) near the bottom of the beam.

Learning Outcomes:

Viewers will gain an improved understanding of:

• The strength properties of timber
• The influence of defects on strength

The beam is subjected to four-point bending. As the test proceeds, cracks start to appear within the knot. Splitting failure eventually occurs above the knot. The ultimate failure load is approximately half that of a beam free of defects.

Structures expert, Doctor Christian Malaga-Chuquitaype of Imperial College, London narrates this video. Doctor Malaga-Chuquitaype is a Lecturer and Assistant Professor in the Structures Section at Imperial College’s Department of Civil Engineering.

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