Lecture Notes on Structural Bracing and Load Distribution

Overview of Bracing

• Braces are diagonal members that carry tension and compression forces.
• Primarily withstand lateral or horizontal loads, such as wind.
• Increase stability and provide auxiliary support.
• Typically represented by straight lines in diagrams.

Function

• Example: Force applied from the top left:
  • Purple brace: in compression.
  • Blue brace: in tension.
• Example: Force applied from the top right:
  • Blue brace: in compression.
  • Purple brace: in tension.
• When braces carry a force, one is compressed, the other is in tension.

Structural Stability

• Without braces, strong loads could cause building collapse.
• Brace colors indicate different load responses (e.g., blue for compression, green for tension).

Structural Framing Types

Trusses

• Carry forces in both tension and compression without moments.
• Composed mostly of triangles.
• Connections are pin joints (carry movement, not moments).
• Forces applied typically at joints.
• Force distribution: Vertical downward forces pass to bottom members, then outwards.

Example

• Real-life truss: Identify the truss and draw force arrows.
• Forces in tension and compression distribute in the direction of green arrows.

Frames

• Have full moment connections (transfer bending and moments).
• Members can carry forces by bending as well.
• Loads can be applied along the members, not just the joints.

Example

• Frame structure: Force applied vertically downwards at the top.
  • Top beam carries load by bending (green arrows).
  • Columns carry force through compression (purple arrows).

Load Distribution in Door Frames

• Example: Vertical downward point force at the middle of a door frame.
  • Top beam distributes force outwards by bending.
  • Columns carry load by compression, transferring it to the ground.
• Visual representation of load path through blue arrows.

Note: Arrows represent load path distribution, not how forces are carried by members.