-
What is LOAD
force acting on structure
-
Force =
mass x acceleration: Newtown's Second Law of Motion
-
Static/Gravity loads, applied slowly
- 1. Live loads (people, furniture, movable equipment, snow)
- 2. Dead loads (building structure, immovable equipment)
-
-
Dynamic and lateral loads, applied suddenly
Wind, seismic, impact loads
-
Beams, loads are typically limited by bending stress and deflection
-
What is STRESS
load or force per unit area
-
External Stresses
- Tire pressure, p.s.i (pounds per square inch)
- Residential floor systems are required to support 40 p.s.f. (pounds per square foot)
-
Internal Stresses
Tensile, Compressive, Shear, Bending Stress
-
Tensile Stresses
- "pulling" force acting through the axis of the structure.
- include: chain, cable, rod and rope
-
Compressive stresses
- "pushing" force acting through the axis of the structure
- include: columns and bearing walls
-
Shearing stresses
- "slipping" force acting through the structure
- Vertical shear occurs perpendicular to the major axis of the structure (scissors work by applying shear perpendicular to the paper surface)
- Horizontal shear occurs parallel to the major axis of the structure (loading a beam introduces horizontal shear)
-
Bending Stresses
- Coupled "pulling" and "pushing" forces acting parallel the axis of the structure.
- Gravity loads on a simply supported beam causes tensile stresses in the bottom of the beam and compressive stresses at the top of the beam
- Maximum allowable loads are typically limited by bending stress
|
|
