L02 PROPERTIES OF MATERIALS

L02 PROPERTIES OF MATERIALS

1. Fundamental Requirements

   • To enclose space
   • Withstand forces and transmit them to the ground
   • have a load path

2. Building Loads

   • weight imposed by the building itself
   • weight of snow or rain
   • Wind Loads
   • Weight of Occupants and Contents

3. Force

   • Definition: Force is that which produces a deformation in a material

4. Strength

   • Measure of load-bearing ability
   • Force required to fracture a sample of material
   • Need to take account of dimensions
   • Concept of stress
   • Definition: Maximum stress which can be withstood before fracture.
   • Units: N/m2 where 1N= 101.972G

5. Stress

   • Tensile stress
     • Perpendicular to the area
     • Direct stress
     • indicated by "sigma"
   • Compressive stress
     • Perpendicular to the area
     • Direct Stress
     • Indicated by "sigma"
   • Shear
     • Parellel to area
     • indirect stress
     • indicated by "tau"
   • Direct Stresses and Indirect stresses
     • Bending
     • Torsion

6. Material Uses and Stresses

   • High tensile strength does not mean high compressive strength for a material
   • Materials are used in accordance with their strength values.

7. Steel

   • High strength in Tension
   • High strength in compression
   • High strength in shear
   • High strength in bending

8. Strain

   • Strain= change in dimension over the original dimension
   • No units, just a ratio
   • Tensile and Compressive