L2: Building Structures Flashcards

1
Q

What is the main function of buildings?

A

To protect occupants from weather

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the excess margin modern safety factors call for and what does this cover?

A

50-150% increase in structural capacity; covers minor material flaws, inaccuracies and other unavoidable errors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How does structure impact design for short/high rise buildings?

A

Short - design is common sense

High - structure highly affects design and appearance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What three items must be present in a building structure?

A

Stability
Strength and stiffness
Economy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What causes unstable structures to form?

A

Unbalanced forces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What do stable structures do under realistic loads?

A

Remain at rest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How stiff is wood compared to steel

A

Wood is less than 16 times steel’s stiffness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the types of building loads?

A

Dead (fixed), live (moving, weather)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What do forces do?

A

Exert motion or stress within a structural member

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How can loads be distributed?

A

Uniform or concentrated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the types of forces?

A

Vertical
Horizontal
Moment (rotational)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How are vertical and horizontal forces balanced by a structure?

A

Vertical - with building foundation (accumulative)

Horizontal - bracing of structural frame (each floor separate)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is stress and what stress occurs within materials?

A

Internal resistance to an applied force; compression, tension, shear, bending

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is compression and what strain does it cause?

A

Crushing/squashing causing shortening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is tension and what strain does it cause?

A

Pulling/stretching causing lengthening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is shear and what strain does it cause?

A

Force perpendicular to long axis; two forces moving against each other causing compression and tension (shortening/lengthening)

17
Q

What is bending (moment) and what strain does it cause?

A

Compression above and tension below the theoretical mutual axis causing deflection (compression and tension)

18
Q

What impacts the amount of bending?

A

Distance from point of rotation stiffness of materials

19
Q

Where is bending stress greatest in a uniform load, point load, and cantilever (uniform or point)

A

Uniform - midspan
Point - at point
Cantilever - at support

20
Q

What is the strain of materials?

A

The external reaction to an applied load

21
Q

What determines a structures resistance to compression, tension and shear

A

Strength of material and cross sectional area

22
Q

What stresses are steel good in?

A

All

23
Q

What stress is concrete good in and what must be done to handle the other stresses?

A

Good in compression

Reinforced with rebar to handle tension
Reinforced with stirrups to handle shear

24
Q

What determines a structures resistance to bending?

A

Moment of inertia; higher proportion of depth to width decreases deflection

Efficiency in shape - material bulk at centre is inefficient and adds dead load

25
Q

What is a bearing wall?

A

A wall that supports any vertical load in addition to its own weight; system of compression materials most efficient if loaded uniformly

26
Q

What are bearing walls limited by?

A

Height - would need thick base to support cumulative loads

27
Q

Where are bearing walls used?

A

Common wood frame house - exterior and some interior walls support vertical loads

Tilt-wall construction (eg. shopping centres) - reinforced concrete formed and poured on ground and then lifted into position

Arches

28
Q

Explain the forces in arches

A

Keystone sends compression loads to base of arch; these have vertical components which go into the ground and horizontal components which cause outward thrust

29
Q

How is outward thrust handled?

A

Counterweighted - more mass alongside arch or arches placed in series (oppose)

Tied - tension cable/rod placed at base

30
Q

What is a post and beam structure?

A

A system of horizontal and vertical members subject to bending, compression and shear; not laterally stable

31
Q

What is the structural element hierarchy

A
Floor slab/deck
Joists
Beams
Girders
(Vertical) columns
32
Q

What does a floor slab/deck do?

A

Initially receives live loads

33
Q

What do joists do?

A

Directly support slab/deck

quite flimsy, closely spaced

34
Q

What do beams do?

A

Receive loads from joists (or directly support floor if no joists)

35
Q

What do girders do?

A

Receive loads from beams

36
Q

What do columns do?

A

Receive loads from beam/girders and above columns to transfer to foundation

37
Q

What are trusses?

A

Triangular spanning elements with axial tension and compression, commonly used to support roofing