Week 2

Question 1

What loads are buildings subjected to?

Answer 1

• Dead loads
• Live loads
• Wind loads
• Earthquake loads
• Loads due to soil pressure
• Loads due to hydrostatic/hydrodynamic pressure

Question 2

What is hydrostatic pressure?

Answer 2

The pressure exerted by a fluid at equilibrium at any point of time due to the force of gravity

Question 3

What is hydrodynamic pressure?

Answer 3

The pressure a fluid exerts on an object due to the object’s motion through a fluid

Question 4

What are the 3 axes of structural elements?

Answer 4

1. Longitudinal axis
2. Major Axis
3. Minor Axis

Question 5

How is the longitudinal axis viewed?

Answer 5

Parallel to length

Question 6

What are the types of stresses in building elements?

Answer 6

• Axial stresses
• Bending stresses
• Shear stresses
• Torsional stresses

Question 7

What is tensile stress?

Answer 7

Pulling apart from two points

Question 8

What is compressive stress?

Answer 8

Pushing in from two points

Question 9

What is shear stress?

Answer 9

Pulling apart from 2 points on different planes

Question 10

What are the characteristics of ‘axial stresses’?

Answer 10

• Load along or in the transverse direction of the line (longitudinal axis)
• Axial loading can be compression or tension

Question 11

What is the load-stress relationship equation?

Answer 11

Stress = Load / cross-sectional area

Question 12

What are the characteristics of ‘bending stresses’?

Answer 12

• Transverse loading induces bending stresses
• Top part of beam is subjected to compression
• Bottom part of the beam is subjects to stretching (tensile stress)

Question 13

What are the characteristics of ‘shear stresses’?

Answer 13

• Developed by transverse loading
• Tends to deform the beam along a plane by slippage

Question 14

What must buildings adequately have?

Answer 14

• Sound performance
• Heat performance
• Daylight provisions

Question 15

What are the two types of waves?

Answer 15

1. Mechanical waves
2. Electromagnetic waves

Question 16

What are mechanical waves?

Answer 16

Requires a medium (solid, liquid, or gas) to propagate

e.g. Sound

Question 17

What are electromagnetic waves?

Answer 17

Does not require a medium to propagate

e.g. light

Question 18

What is the ‘crest’ in reference to wave behavior?

Answer 18

The maximum amount of positive movement from the equilibrium position

Question 19

What is the ‘trough’ in reference to wave behavior?

Answer 19

The maximum amount of negative movement from the equilibrium position

Question 20

What is the ‘wave length’ in reference to wave behavior?

Answer 20

the length between two adjacent crests or troughs (i.e. a cycle)

Question 21

What is the ‘amplitude’ in reference to wave behavior?

Answer 21

The maximum amount of displacement from the equilibrium positions

Question 22

What is the definition of ‘airborne sounds’?

Answer 22

Noises inside a building without physical impact between the building mass and sound source

e.g. voices

Question 23

What is the definition of ‘impact sounds’?

Answer 23

Noises that are a result of physical impact on a building mass

e.g. footsetps, slamming doors

Question 24

How is sound measured?

Answer 24

In dB

Question 25

What is sound insulation?

Answer 25

Construction elements that: absorb, reflect, or diffuse soundwaves e.g. walls and floors

Question 26

What is sound reflection?

Answer 26

- Portion of soundwaves bounced off a construction element - Reflection is suitable when the sound source is outside the building - When the sound source is inside, reflection leads to echo effect

Question 27

What is sound diffusion?

Answer 27

- A larger sound wave is broken into several smaller waves when hit with an irregular surface (e.g. carpet) - Smaller waves have less energy thus travelling less distance - Diffusion suitable for reduction of sound inside a building

Question 28

What is sound absorption?

Answer 28

- Acoustic materials can be engineered to deaden the sound waves (energy) - Acoustic materials can be engineered to achieve the optimum balance between density and porosity.

Question 29

What is the 'Sound Reduction Index (Rw)'?

Answer 29

- Measures the ability of a construction component to insulate airborne noise - +1 Rw approximately equals -1 dB - Sound proofing capacity is measured as Rw+Ctr

Question 30

What is the best form of impact sound insulation?

Answer 30

- Discontinuous construction (reduces vibrations) - Floor topping has a significant influence on the impact of sound resistance

Question 31

What is heat balance?

Answer 31

The desired temperature in a building

Question 32

What are the 3 heat transferring mechanisms?

Answer 32

1. Conduction - Transmission of heat between molecules by direct contact 2. Convection - Transmission of heat through fluids (liquids & gas) 3. Radiation - Transmission of heat from one radiant energy source to another without the need of a medium

Question 33

What is thermal comfort determined by?

Answer 33

1. Thermal mass 2. Thermal resistance

Question 34

What is thermal mass?

Answer 34

The ability of a construction material to absorb and store thermal energy

Question 35

What is the equation showing the relationship between thermal energy, mass, and temperature rise?

Answer 35

Q = m C ∆T Q: thermal energy absorbed/released C: Thermal mass or specific heat ∆T: Temperature difference due to energy absorption or release

Question 36

What are thermal characteristics of heavy construction materials?

Answer 36

Have a beneficial thermal mass, but thermal resistance is low

Question 37

What is the term for thermal resistance?

Answer 37

'R-value' (insulation has high R values)

Question 38

What are the characteristics of daylight on buildings?

Answer 38

- Natural light is an advantage - Unwanted heat gain from sunlight adversely influences thermal comfort - Major light/heat gaining components (e.g. windows) can be oriented according to sun path