Structures 1 Week 2

1
Structures 1 - Week 2

• Idealisation of Structural Forms

2
Idealisation of Structural Forms

• Structural Forms
• Types of Loads
• Support Systems - Reactions
• Structural Idealisation
• Equations of Static Equilibrium
• Calculation of Support Reactions
• Statical Determinacy

3
Structural Forms

• arches
• beams
• trusses
• portal frames
• cables
• slabs, raft foundations
• shells, folded plate roofs, arch dams, etc.

4
Types of Loads

• Point Loads
• Distributed Loads (uniformly, linearly varying,
  etc.)
• Area Loads
• Dynamic Loads

5
Support Systems - Reactions

• Fixed
• Pinned
• Roller

• Horizontal, vertical, rotational
• Horizontal, vertical
• Vertical

6
Structural Idealisation

• Simply supported beam
• Trussed Roof
• Frame
• 2-D or 3-D
• Finite Elements
• Dynamics
• Stress Analysis

7
Equations of Static Equilibrium

• 2-D
• ? Fx 0
• ? Fy 0
• ? Mz 0

• 3-D
• ? Fx 0
• ? Fy 0
• ? Fz 0
• ? Mx 0
• ? My 0
• ? Mz 0

8
Calculation of Support Reactions

• Cantilever
• Simply supported beam
• Truss

9
Statical Determinacy

• A structure is statically determinate if the
  unknowns (i.e. the reactions at the supports and
  the internal stress resultants) can be determined
  entirely from the equations of static
  equilibrium.
• If the unknowns are more than the equations of
  static equilibrium the structure is statically
  indeterminate.
• The indeterminacy of a structure may be internal,
  external, or both.