Structural Systems Flashcards
(107 cards)
1
Q
What are the different loads a building needs to carry?
A
Dead Loads
Live Loads
Environmental loads
2
Q
What are the characteristics of dead loads?
A
Stationary or constant over time
Vertically downwards
3
Q
Give examples of dead loads?
A
Weight of the building structure, walls, built-in furniture, etc…
4
Q
What are the characteristics of live loads?
A
Temporary or variable
May be concentrated or distributed
5
Q
Give examples of live loads?
A
Occupants, furniture and equipment
6
Q
What are the different environment loads?
A
Wind loads Earthquake Settlement over time Thermal Hydrostatic
7
Q
For what kind of buildings wind loads are more important?
A
Gets importance w/ height, lighter materials and shapes that affect the flow of air
8
Q
What direction of load an earthquake can impose to a building?
A
Horizontal loads
9
Q
How the settlement of a building can add to its load?
A
Different parts of a building can settle differently than others. This difference causes stresses. Ideally the whole building goes down at the same time.
10
Q
How to prevent settlement damage to a building?
A
The structure of a building must have a degree of flexibility, so small stresses can occur.
11
Q
How thermal loads can damage a structure?
A
Materials expand and contract with change in temperature. This changes can apply loads on a structure.
12
Q
How to prevent thermal loads damage?
A
Provide expansion joints to provide of materials movement.
13
Q
Which part of a building is more susceptible to hydrostatic loads?
A
The basement
14
Q
To where the different systems of a building transfer its load?
A
To the foundations and from there to dissipate into the soil
15
Q
What are the different elements that constitute the structural system of a building?
A
Foundation Systems
Floor Systems
Wall Systems
Roof Systems
16
Q
What constitute the superstructure of a building?
A
Everything above and except the foundation (floor systems, wall systems, roof systems)
17
Q
What is the function of the foundation of a building?
A
To receive its entire load and transfer it safely to the ground. Accommodate the structure above and respond to the soil conditions
18
Q
What is maximum allowable bearing pressure?
A
The different mechanical capacity of each type of soil has to resist loads
19
Q
Why it is important that the footing of a foundation be placed bellow the frosting line?
A
In order to minimize the effects of ground heaving when groundwater freezes and expands in cold weather
20
Q
How deep the footing should be in Toronto to be bellow the frosting line?
A
Generally 4’ is enough. In Montreal the minimum is 6’
21
Q
When shallow foundations (up to 10’) are employed?
A
When stable soil of adequate bearing capacity is relatively close to the surface.
22
Q
What is the function of a foundation footing?
A
Transmit loads directly to the soil
23
Q
What are the 2 different types of footing?
A
Strip foundation: continuous footing to support a row of columns or wall
Isolated foundation: Individual spread footing
24
Q
When deep (beyond 10’) foundations are employed?
A
When soil is unstable or of inadequate bearing capacity.
25
Give an example of a type of deep foundation
Pile foundation - uses friction to dissipate loads to soil
26
What are floor systems?
Horizontal planes that support loads and transfer them horizontally across the space to either beams and columns or to load-bearing walls.
27
How floor systems can be composed?
A series of linear beams and joists overlaid with a plane of sheathing (steel or wood)
A homogeneous slab of reinforced concrete.
Composite floor slab: concrete slab + steel decking (steel rebars are used within the concrete slab for tension reinforcement)
28
What defines the depth of a floor system?
The size and proportion of the structural bay it must span and the strength of the materials used
29
What is the limitations of using steel decking or wood planks on a floor system?
Relatively short span, joists have limited overhang potential
30
How beams of a floor system may be supported?
By girders (support beam), posts or load bearing walls
31
What is the advantage of a joist framing of a floor system?
It is flexible in shape and form
32
How to estimate the depth of a concrete beam?
span/16
33
How to estimate a concrete beam width?
Beam width is 1/3 to 1/2 of beam depth in 2" to 3" (50 or 75) multiples
34
How the width of a concrete beam relates to its support column
The width of the beam should be equal or greater than the width of its supporting column
35
Rule of thumb to estimate thickness of one-way concrete slab structure
Span/30 for floor slabs (minimum of 4")
| Span/36 for roof slabs
36
When steel framing is most efficient?
When the girders and beam supports are laid out along a regular grid
37
How to add resistance to lateral forces and earthquake to a steel structure?
Adding shear walls, diagonal bracing or rigid framing with moment-resisting connections
38
How steel connections are made?
They usually use transitional elements like steel angles, tees or plates that are bolted, riveted or welded together
39
For which application a steel one-way beam system is most suitable
For long, narrow buildings when a column-free space is desirable
40
What is the typical span of steel beams?
20' to 36' (6 to 10m), above this range an open-web steel joist become an economical alternative due to its light weight.
41
What is the space between beams on a steel frame structure?
6' to 15' (1830 to 4570)
42
What are the advantages and disadvantages of framing steel beams to girders?
Minimizes floor depth. Some mechanical can pass through holes cut into the beams. A suspended ceiling bellow might be needed to accommodate for larger mechanical elements
43
What are the advantages and disadvantages of a two-layer steel framing?
Increase floor depth considerably
| Provides more space for mechanical systems.
44
What are the types of steel beam connections?
```
Moment connections (AISC type 1) - rigid frame, plates welded or bolted to the beam flanges and supporting column
Shear Connections (AISC type 2) - simple frame - connections are made to resist only shear and are free to rotate under gravity load. Shear walls or diagonal bracing is required for lateral stability of the structure
Semi-rigid connections (AISC type 3) - semi-rigid frame, limited but known moment resisting capacity
```
45
What are the types of steel beam shear connections
Framed connection - welding or bolting the web of a beam to the supporting column or girder
Seated connection - welding or bolting the flanges of a beam to the supporting column
46
What is the space of joists on a steel open-web joist framing?
2' to 10' (610 to 3050) depending on the magnitude of floor load, spanning capability of decking material, load carrying capacity of joists, and the floor construction depth desired.
47
How to prevent lateral movement of joists on a steel open-web framing?
Horizontal or diagonal bridging to prevent lateral movement of joists chords.
48
Spacing of wood joists on a wood light-frame construction?
12", 16" or 24" (305, 405, or 610) o.c., depending on the magnitude of applied loads and spanning capability of the subflooring
49
On a wood light-frame construction what is accommodate between joists?
wiring, piping, thermal insulation
50
what is one of the functions of subflooring?
Ties and stabilizes the joists to prevent twisting and buckling
51
What can be done to end joists to provide additional support for perimeter walls?
They can be doubled
52
What is the support required for joists ends called?
Rim joist or header
53
What are the ways of supporting wood joists?
Stud framing, wood or steel beams, or a bearing wall of concrete or masonry
54
What is the minimum area of a wood joist that needs to be supported on a beam or wall
1 1/2" (38) on wood or metal
| 3" (75) on concrete or masonry
55
How to estimate the joist depth?
span/16
56
What is important in a wood joist framing? How to obtain it?
The stiffness of the joist framing is more critical than its strength. If the depth of construction is acceptable, deeper joists spaced further apart is preferable to shallower joists closer together.
57
In which direction wood is most susceptible to shrinkage?
perpendicular to wood grain
58
Types of wood joists framing? (pg474-476)
```
Wood beam with joists hangers
Steel beam with ledger
Wood beam with ledger
Steel beam under joists
Wood beam with lapped or spliced joists
```
59
Where should a splice be located on a continuous span?
On the points of minimum bending stress, approximately at 1/4 or 1/3 of the span
60
Based on the configuration of a wall what they can be?
Structural frames: horizontal and vertical load bearing systems (concrete, steel or wood)
Concrete or masonry bearing walls
Studded walls (wood or metal studs spaced generally 16" O.C.). Need to be stiffened by either wall sheathing or diagonal bracing.
61
How columns should be oriented on a steel frame structure?
Web parallels to the short axis of structural frame or along which the structure is most susceptible to lateral forces
Flanges on perimeter columns should be oriented to the outside
62
Examples of ways to build roof systems:
Structural steel roof framing: flat, similarly to floor systems
Steel rigid frames
Trusses: wood or steel, triangular framework gives stability to truss
Wood rafters - wood, easily assembled on site
63
What are the different types of Trusses Roof systems?
Flat, Pratt, Belgian, Scissor.
64
What is the different species of wood of SPF Lumber?
Canadian Spruces, Pines and Fir (SPF)
65
Why SPF lumber is considered a green way to build?
Because there is no waste, all scraps of wood is used to create manufactured wood products such as plywood, MDF and particle board
66
Why nominal size of SPF is smaller than actual size?
Wood shrinks during drying process
67
What are actual sizes for nominal sizes 2x4, 2x6, 2x8, 2x10, 2x12?
```
1 1/2 x 3 1/2
5 1/2
7 1/4
9 1/4
11 1/4
```
68
What is SCL?
Structural Composite Lumber - engineered wood products
69
What are the most widely used SCL products?
Laminated Veneer Lumber (LVL)
| Parallel Strand Lumber (PSL)
70
Characteristics of LVL
Thin layers of wood veneer bond together in a large billet
All veneers' grain parallel to long direction
Lengths far beyond conventional lumber lengths
71
Applications of LVL
Headers, beams, flange material for prefabricated wood I-Joists.
72
Characteristics of PSL
Veneers strands bond together with and adhesive under high pressure
Strands aligned parallel to increase strength
73
Applications of PSL
Headers, beams, load-bearing columns
74
PSL is known by its most common brand name, which is?
Parallam
75
What are I-Joists?
Strong, lightweight, "I" shaped engineered wood structural members
76
What are the parts of I-Joists?
Top and bottom flanges (resist bending), united with webs.
77
What materials are used to make the flanges of I-joists?
LVL or solid sawn lumber
78
What material is used to make the web of I-Joists?
Plywood or OSB (Oriented Strand Board)
79
What is the most widely-known brand of I-Joists?
Trust Joist - TJI
80
What are wood Trusses?
Engineered frames of lumber joined together in triangular shapes by galvanized steel connector plates (truss plates).
81
What are the advantages of using Trusses?
Design regulated by provincial or territorial building codes.
Custom made
Allow to create large open spaces that architects and designers can use with complete freedom
82
What is the disadvantage of Roof Truss?
Its members shall not be notched, drilled or otherwise weakened unless allowed for in the design
83
What are the disadvantages of Floor Trusses?
Not all are easily adjustable on site - can lead to delays
Installation of mechanics can be hindered by sharp metal plates (e.g. can damage wires)
Depending on plate size, they can reduce the amount of space for HVAC
84
What are the advantages of Open joist?
Combines the advantage of open web design found in floor truss with access to stock material and trimmability of I-Joist.
Made entirely of wood - lighter and easy to install
85
What is the known manufactures of Open Joist?
Triforce
86
How plywood is made?
Thin sheets of cross-laminated veneer, bonded under heat and pressure with strong adhesives.
87
What are the advantages of plywood?
Highly resistant to impacts, chemicals and changes in environmental temperature and humidity
88
Common application of plywood in construction?
Subflooring, wall and roof sheathing, web of I-Joists or concrete forming
89
Advantages of OSB (Oriented Strand Board)?
Efficient use of forest resources
| Strong, dimensionally stable panes that resists deflection, delimitation and warping
90
What are the advantage of plywood over OSB?
Behaves better in humidity: gets wet faster, but dries faster, too. Do not deform. OSB gets wet slower, but also dries slower, the edges warp and do not get back.
91
What is HSS?
Hollow Structural Section: type of metal profile with a hollow cross section
92
How HSS dimensions are taken?
Based on exterior dimensions
93
What HSS are used for in construction?
Columns and beams
94
What is the most commonly used type of structural steel?
Wide flange beams and columns (W-beam)
95
Components of W-Beam?
Web - vertical member, holds flanges together
| Flanges - top and bottom horizontal members
96
Which information is provided for a W-Beam?
Height
Width
weight/length (Kg/m or lb/ft)
97
What is the difference between W-Beam and I-Beam on a steel construction?
I-Beam is rarely used, its web is often much thicker and the flanges are tapered.
98
What are the components of concrete?
water, aggregate (rock, sand, or gravel) and cement.
99
Based on its application, how can we classify concrete?
Cast-in-place concrete
| Precast concrete
100
What are the advantages of cast-in-place concrete?
Custom to the build
| Versatile
101
What are the applications of cast-in-place concrete in construction?
Slabs, foundations, beams and columns.
102
What are the disadvantages of cast-in-place concrete?
More costly, labour and time intensive.
Require strength test and time for curing - slower to construct than precast concrete
Can't be poured bellow 0 degrees
103
Advantages of precast concrete
Created off-site using a mold and cured in a controlled environment - eliminate outside variables (weather) - faster construction
Allows for different colours, textures and shapes
104
Common uses of precast concrete
Applications that see a lot of wear and tear: parking structures, foundations, large civil engineering projects (e.g . beams or deck slabs in bridges)
105
What are different ways of build masonry structures?
Bound the individual units by mortar
| "Dry stack" - units bond together by interlocking systems, reinforcements or weight-gravity
106
What are the most frequent materials used in masonry?
Brick
Concrete masonry unit (CMU) - solid or hollow
Natural stone
107
What is the advantage of using CMU for foundation walls?
Cheaper than cast-in-place concrete
| Lighter weight makes them easer to work with
