Structure 1

Question 1

Structure

Answer 1

• Structures are both natural and designed.
• Structures control and order the flow of physical force, caused by the loads of the building itself and those applied to it.
• The structure transfers the load from the building, around the internal space to the ground – foundations.

Question 2

Loads

Answer 2

Dead (or Permanent Load): The weight of the building (floors, walls and roof).

Live (or Occupancy Load): People, furniture, etc. Variable and difficult to assess. Based on standard assumptions.

Wind Load: Buildings obstruct wind flow. The energy of movement is converted to a pressure acting on the exposed surface of the building, vertical, inclined and horizontal.

Question 3

What is Structure?

Answer 3

• A series of component parts, that are connected and positioned in an assembly to resist loads.

Examples

Linear: Beams, Columns, Cables

2D: Walls, Floors, Trusses

3D: Shells, Membranes, Grids

Question 4

Structure Types

Answer 4

Question 5

Requirements of Structures

Answer 5

For Structures to work successfully when subjected to various loads, they have to fulfill 4 fundamental requirements:

Equilibrium

Geometric Stability

Adequate Strength

Adequate Stiffness

Question 6

Requirements of Structures:

Equilibrium

Answer 6

• The structure must be in equilibrium in response to the loads (forces) applied to it; it should remain in place without moving horizontally, vertically etc.,
• This state of remaining in place is known as Static Equilibruim. The principle of Static Equilibrium is the most important concept in understanding structural concepts.
• Elements which are provided solely for stability and which do not contribute directly to resisting the principal load are called Bracing elements.

Question 7

Requirements of Structures:

Geometric Stability

Answer 7

• Rectangular arrangements are fundamentally unstable. Bracing can be used to give these arrangements stability
• It is not necessary to brace every panel in a rectangular framework to make it stable, e.g. a row of frames is stable when only one panel is braced
• In a multi-storey arrangement, bracing must be provided at every level

Stability of Frames

• It is important to arrange bracing to minimise its impact on the use of the space, and in many cases the bracing utilises floor planes and vertical structural elements
• Vertical-plane bracing is normally arranged around stairs and lift wells

Question 8

Requirements of Structures:

Adequate Strength

Answer 8

• Loads imposed on buildings generate internal forces in the structural elements, structural elements must be strong enough to resist these internal forces.
• Strength relates to the material and the size and shape of elements.

Question 9

Requirements of Structures:

Adequate Rigidity (Stiffness)

Answer 9

• All materials deform under the action of load.
• Excessive deformation may cause the building to become unusable orunserviceable, E.g. cracking of finishes, windows not opening or excessive vibrations.