1. Topic 4 – Forces, Loads and Stresses

2. Forces
External Forces are stresses that act on a structure from outside the structure.
These in turn cause INTERNAL FORCES that can damage the structure.

3. External forces Dead loads do not change
Example: walls, floors, roofs, ceilings, stairways…
Live loads Can change
Example: Wind, rain, earthquakes, tides, floods, snow..

9. Internal Forces There are a bunch of forces…. Tension  Pulling force
Tensile Strength- Measures the largest tension force the material can withstand before breaking
Compression  Squishing force
Compressive Strength
Shear  Tearing force
Shear Strength
Torsion  Twisting
Torsion Strength

14. Draw these in your book and Label

15. LAB!!
Examining Forces….
Investigation 4D on page 310.