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CMGT 110- Test 3 > Final Exam > Flashcards

Final Exam Flashcards

1
Q

How are earth materials classified for foundation design?

A

According to particle size, organic content, and sensitivity to moisture

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2
Q

What is the primary characteristic of consolidated rock (bedrock)?

A

It is dense, continuous, and can be removed by drilling or blasting

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3
Q

Which of the following is NOT a type of particulate soil defined by ASTM D2487?

A

Peat

-Peat, topsoil, and other organic soils are not suitable for the support of building foundations.

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4
Q

Which soil particles are generally flat or plate-shaped?

A

Clay

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5
Q

What is the primary factor that gives cohesive soils their strength?

A

Cohesion between particles

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6
Q

Which soil type tends to expand or contract with changes in moisture content?

A

Clay

-Clay soils may also be expansive, that is, prone to expand or contract with changes in moisture content. Clays with very small particle size and high liquid limits are most susceptible to this behavior.

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7
Q

What is the term used to describe the gradual reduction in soil volume due to water being pressed out of it?

A

Consolidation

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8
Q

Which type of soil is most susceptible to soil liquefaction during an earthquake?

A

!Sand! , Gravel , Silt

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9
Q

What is the primary purpose of the Unified Soil Classification System?

A

To classify soil based on particle size and other properties

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10
Q

What is the maximum allowable slope or angle of repose?

A

The angle at which soil will not slide back into an excavation

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11
Q

What is the purpose of slurry in a slurry wall construction?

A

To exert pressure against earth walls and hold them in place

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12
Q

What is the purpose of tiebacks in excavation support?

A

To anchor and stabilize the shoring while maintaining an open excavation

-Where soil conditions permit, tiebacks can be used instead of bracing to support the shoring while maintaining a fully open excavation.

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13
Q

Which type of soil is commonly used for general-purpose fill due to its compaction and stability?

A

Gravel , Sand

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14
Q

What is the primary purpose of crosslot bracing or sloping rakers in excavation support?

A

To brace the shoring against earth and water pressures

-As an excavation deepens, its support system must be braced against earth and water pressures (Figure 2.20). Crosslot bracing uses temporary steel wide-flange columns that are driven into the earth at points where braces will cross. As the earth is excavated down around the shoring and the columns, tiers of horizontal bracing, usually of steel, are added to support walers, which are beams that span across the face of the sheeting. Where the excavation is too wide for crosslot bracing, sloping rakers are used instead, bearing against temporary footings.

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15
Q

What is the significance of the term “gradation” in soil mechanics?

A

It refers to the range of particle sizes present in a soil sample

-Within any soil sample, the range of particle sizes present, or gradation, may vary.

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16
Q

Which soil type exhibits greater resistance to internal sliding due to friction between particles?

A

Cohesive soils

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17
Q

What is the primary benefit of using tiebacks over traditional bracing methods?

A

They allow for a fully open excavation without obstructions.

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18
Q

What does the term “water table” refer to in soil mechanics?

A

The elevation at which soil is fully saturated with groundwater

-Water below the ground surface is called groundwater, and the elevation at which soil is fully saturated with groundwater is called the water table.

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19
Q

What is the primary role of slurry walls in foundation construction?

A

They serve as excavation support and may become part of the foundation

-A slurry wall is a more complex method of constructing a complete, steel-reinforced, concrete wall in the ground, even many stories below the surface, before excavation takes place. It is a relatively expensive form of excavation support that is usually economical only if it becomes part of the permanent foundation of the building.

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20
Q

What is the purpose of backfilling in construction?

A

To compact the soil for stability

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21
Q

What is the primary role of a foundation?

A

To prevent building collapse

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22
Q

Which type of loads act on buildings?

A

Dead load, live load, rain and snow loads, wind loads, seismic loads, soil and hydrostatic pressure loads

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23
Q

Which load includes the weights of occupants, furnishings, and movable equipment?

A

Live load

-Live loads, nonpermanent loads caused by the weights of the building’s occupants, furnishings, and movable equipment

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24
Q

What is a major concern when it comes to building foundations settling?

A

Encouraging uniform settlement , Minimizing differential settlement , Avoiding structural distress and damage to nonstructural components

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25
What kind of settlement occurs when different parts of a building settle at different rates?
Differential settlement
26
What can differential settlement lead to?
Distorted building frame, cracked walls, and inoperable doors
27
Which type of foundation encloses habitable space below ground?
Substructure -the habitable portion below ground
28
What is the purpose of well points in dewatering an excavation?
To lower the water table around the excavation -Well points are used to depress the water table.
29
Which method of dewatering is commonly used in excavations to keep them dry?
Pumping water from pits (sumps) -The most common method of dewatering is by pumping as the water accumulates in pits, called sumps, located at low points in the excavation.
30
What is the primary purpose of spread footings?
To distribute concentrated loads from above -Spread footings take concentrated loads from above and spread them out across an area of soil large enough that a safe soil pressure is not exceeded.
31
What is the main reason for using caissons or piles in foundation construction?
To reach more suitable bearing strata beneath the substructure - Caissons are concrete cylinders poured into drilled holes. They reach through weaker soil to bear on competent soil beneath.
32
What type of foundation is practical when closely spaced bearing strata can be reached?
Mat foundation
33
Which type of foundation can develop load-carrying capacity through frictional resistance?
Friction pile foundation - If no firm bearing layer can be reached, a pile may still develop a considerable load-carrying capacity through frictional resistance between the sides of the pile and the soil through which it is driven; in this case, it is known as a friction pile.
34
What is the purpose of reinforced concrete pile caps?
To distribute the load of the column or wall above among the piles -Pile caps are reinforced to transmit column loads equally into all the piles in the cluster
35
What type of foundation is heavily reinforced and may be 6 feet or more in thickness?
Mat foundation
36
Which method of pile installation relies on heavy weights dropped on top of the pile?
Pile hammering -Conventional piles are driven with pile hammers, heavy weights lifted by the energy of steam, compressed air, compressed hydraulic fluid, or diesel fuel combustion, then dropped on the top of the pile.
37
What type of foundation would be appropriate in areas with excessive differential settlement concerns?
Deep foundations , spread footings
38
In which situation would well points be an ineffective dewatering method?
When the water table is low
39
What type of loads primarily act downward on building roofs?
Rain and snow loads
40
What is the primary purpose of a foundation’s mat (raft) foundation?
To support the entire building on low-bearing capacity soil -In situations where the bearing capacity of the soil is low in relation to building loads, column footings may become so closely spaced that it is more effective to merge them into a single mat (raft) foundation that supports the entire building.
41
What materials can piles be made of?
Wood, steel, concrete, or combinations of these materials -Answer is weak and may be different
42
What is a primary advantage of timber piles?
They are economical for lightly loaded foundations - A primary disadvantage is that they cannot be spliced during driving and are, therefore, limited to the length of available tree trunks, or approximately 65 feet
43
Which pile type displaces relatively little soil during driving?
H-piles, Mini-piles
44
What type of pile can be brought to the site in convenient lengths, welded together, and cut as needed?
H-piles -Made from scrap metal
45
What is a potential problem with closed pipe piles during driving?
They may cause upward heaving of nearby soil
46
What is the main advantage of helical piles for installation?
They avoid vibration and noise during installation.
47
What is the range of bearing capacity for mini-piles and helical piles?
2 to 200 tons (18 to 1800 kN)
48
Which type of foundation element can be used to reduce the risk of liquefaction in soils?
Rammed aggregate piers
49
What is the purpose of drainage in foundation construction?
It reduces water pressure against the foundation’s walls and slabs. -Drainage draws groundwater away from a foundation, reducing the volume and pressure of water acting on the foundation's walls and slabs.
50
What is the purpose of damp-proofing in foundation walls?
To resist mild groundwater conditions
51
Which type of waterproofing membrane is sprayed or rolled on as viscous liquids that cure in place?
Liquid-applied membrane
52
What type of retaining wall relies on the mass of the wall and interlocking units for resistance?
Unreinforced construction -For small retaining walls, unreinforced construction methods are used that rely on the mass of the wall, interlocking units, or other simple techniques to develop adequate resistance to soil pressures
53
What is the primary factor that determines the design of a retaining wall?
Soil type , wall height , pressures acting on the wall
54
What type of retaining wall relies on the mass of the wall to resist lateral earth pressures?
Gabion wall -Retaining walls of this type rely on the mass of the wall to resist the lateral earth pressures.
55
What failure mechanism occurs when groundwater runs beneath the base of a retaining wall?
Undermining
56
Which material is often used to fill gabion baskets for retaining walls?
Cobble/boulder-sized rocks
57
Which type of retaining wall is designed to lean back against the soil it retains?
Segmental retaining wall
58
What type of retaining wall requires careful design and reinforcement for taller walls or greater loads?
Cantilevered wall
59
What is the main advantage of precast concrete piles?
They have high load capacity and are corrosion-free.
60
What is the primary purpose of drainage mat in retaining wall construction?
To relieve water pressure against the wall -Drainage draws groundwater away from a foundation, reducing the volume and pressure of water acting on the foundation's walls and slabs
61
What is the primary binding agent in concrete?
Cement
62
What is the process by which cement chemically combines with water to form strong crystals?
Hydration -During the hardening, or curing, of concrete, the cement combines chemically with water to form strong crystals that bind the aggregates together, a process called hydration.
63
What is the heat given off during the curing of concrete referred to as?
Heat of Hydration
64
Which type of cement is known for its high early strength and is used in cold weather conditions?
Type III -Type III hardens more quickly than the other types and is employed in situations where a reduced curing period is desired (as may be the case in cold weather)
65
Which ingredient in concrete is responsible for causing microscopic air bubbles to form during mixing?
Air-entraining admixtures
66
What is the purpose of air-entraining concrete?
Increase resistance to freeze-thaw cycles , Improve workability
67
Which type of cementitious material reacts with calcium hydroxide to form cementing compounds in wet concrete?
Pozzolans - Pozzolans are materials that react with the calcium hydroxide in wet concrete to form cementing compounds. They include: Fly ash, Silica fume, Natural pozzolans (pos-o-lynn), Metakaolin
68
What is the primary purpose of supplementary cementitious materials (SCMs) in concrete mixtures?
Enhance various properties of concrete
69
Which test is commonly used to assess the workability of freshly mixed concrete?
Slump test
70
What is the main factor that determines the strength of cured concrete?
Water-cement ratio
71
Which type of concrete does not require vibration for consolidation and fills forms completely on its own?
Self-consolidating concrete (SCC)
72
What is the main reason for curing concrete thoroughly?
To achieve required strength and durability
73
How is the strength of cured concrete commonly measured?
After 28 days
74
What is the purpose of using an immersion-type vibrator on freshly placed concrete?
To eliminate trapped air and fill voids
75
How does concrete react to subfreezing temperatures during curing?
The reaction stops until the temperature rises above freezing
76
In very hot weather, how can the hydration reaction in concrete be controlled?
Use cool ingredients or crushed ice -Another method of cooling concrete is to bubble liquid nitrogen through the mixture at the batch plant
77
What is the primary function of a truck-mounted pump in concrete placement?
Deliver concrete to its final position at height or distance
78
Which type of cement is used when concrete is in contact with water containing high sulfates?
Type V , Type II -Types II and V are used where the concrete will be in contact with water that has a high concentration of sulfates
79
What is the common period used to measure the strength of cured concrete for most practical purposes?
28 days
80
What is the primary purpose of using curing compounds on concrete surfaces?
To prevent loss of moisture - By spraying on a curing compound that seals the surface of the concrete against loss of moisture.
81
What is the primary reason concrete and steel are compatible for use together in construction?
Similar rate of dimensional change with temperature
82
What structural property does concrete lack, making the concept of steel reinforcing essential?
Tensile strength - Concrete has no useful tensile strength
83
Why is steel protected from corrosion when embedded in concrete?
Alkaline chemistry of concrete protects steel
84
What is the basic theory behind reinforced concrete?
Steel resists tensile forces, and concrete resists compression forces
85
What is the purpose of steel bars (rebar) in concrete construction?
To resist tensile forces , and increase compressive strength
86
In the United States, how are reinforcing bars specified in terms of diameter?
Number corresponding to eighths of an inch
87
What is the primary advantage of using welded wire reinforcement (WWR) in concrete construction?
Economizes labor in placing reinforcing
88
What is the purpose of stirrups in reinforced concrete beams?
To resist diagonal tensile forces
89
Which ASTM standard provides reinforcing bars with low-alloy steel for seismic design criteria?
ASTM A706 - W for ASTM A706 low-alloy steel ASTM A706 reinforcing bars are made with low-alloy steel that exhibits well-controlled ductility and is easily welded
90
What type of construction uses tightly stretched steel strands cast into concrete?
Pre-tensioning - Pre-tensioning is used with precast concrete members: High-strength steel strands are stretched tightly between abutments in a pre-casting plant before the concrete is cast.
91
What is the primary purpose of pre-tensioning in concrete construction?
To create compression in the concrete member - After the concrete has cured to a specified minimum compressive strength, the strands are cut off at either end of each member. This releases the external tension on the steel, allowing it to recoil slightly, which squeezes all of the concrete of the member into compression.
92
How is a simple rule of thumb used to determine the placement of bending steel in a beam?
By drawing lines of the beam's shape under load
93
What happens to the concrete in a prestressed member when high-strength steel strands are cut after tensioning?
It is compressed by the pre-stressing forces
94
What is the main advantage of posttensioning over pre-tensioning in concrete construction?
Flexibility in on-site construction
95
What term is used to describe the downward-pointing or flattened V shape formed by pre-tensioning strands?
Harped Strand
96
Which factor contributes to the need for slightly increased initial pre-stressing forces in prestressed members?
Concrete creep and steel stretching over time
97
What property of concrete is primarily responsible for the creep effect in prestressed members?
Long-term deformation under sustained load - This is not a property of concrete it is a property of concrete under a load, this is poorly worded
98
What does ASTM stand for in the context of concrete construction standards?
American Society for Testing and Materials
99
In what way are spiral-tied columns different from column ties?
They are shipped to the construction site as tight coils
100

CMGT 110- Test 3 (4 decks)

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