1. Final Project - Structural Flashcards

1
Q

What is the internal resistance to an external force?

A

Stress. (Tension, Compression, Shear, Torsion, Bending, Combined Stresses)

Stress f = total force P / total area A

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2
Q

What are the three basic types of stress?

A

Tension, compression, and shear

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3
Q

What is tension?

A

Tension is stress in which the particles of the member tend to pull a part under load.

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4
Q

What is compression?

A

Compression is stress in which the particles of the member are pushed together and the member tends to shorten.

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5
Q

What is the deformation of a material caused by external forces?

A

Strain (e)

strain (e) = total strain e / original length L

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6
Q

What is shear?

A

Shear is stress in which the particles of a member slide past one another.

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7
Q

What is Hooke’s law?

A

As a force is applied to a material, the deformation (strain) is directly proportional to the stress, up to a certain point.

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8
Q

Ultimate Strength

A

The failing point of a given material.

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9
Q

Yield Point

A

On a stress-strain graph, the point at which the material begins to deform with minimal increase in load (stress).

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10
Q

Elastic Limit

A

On a stress-strain graph, the point at which the material will experience deformation faster. (Prior to to this point stress and strain are directly proportional.)

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11
Q

Coefficient of Expansion

A

Thermal Stress

plastic, acrylic = 0.0000450
aluminum = 0.0000128 in/in-F
bronze = 0.0000101
structural steel = 0.0000065
concrete = 0.0000055
glass = 0.0000051
marble = 0.0000045
brick = 0.0000034

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12
Q

Question: What is the applied force called in the following diagram?
→ ▯ ←

A) Shear
B) Compression
C) Torsion
D) Traction

A

B) Compression

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13
Q

Newton’s 3rd law

A

For every force acting on a body (building) there is an equal force of opposite magnitude.

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14
Q

List & define the 3 types of forces which may impact a structural body.

A

1 - COLLINEAR = along the same line of action *sum of vectors = magnitude along same line of action

2 - CONCURRENT = vectors that intersect at one point *sum of vectors with parallelogram polygon method

3 - NON-CONCURRENT = moment or rotation forces *sum of vectors = moment arm = F X d

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15
Q

Shear & moment forces are best resisted with which construction types?

A
  • RIGID CONNECTIONS (Least efficient, only good for small buildings)
  • SHEAR PLANES
  • BRACING
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16
Q

2 types of loads

A

Static & dynamic

17
Q

2 types of static loads

A

Dead & Live

18
Q

4 types of live loads

A

1 - Occupant & moveable furniture / equipment

2 - Snow

3 - Rain

4 - Impact (kinetic loads of short duration - cosidered static by Code *amplify load to compensate for its dynamic nature)

19
Q

2 Common types of dynamic loads

A

Wind & seismic

20
Q
  • Name 3 criteria governing the choice and use of a construction material.
  • How should these criteria be for a material to be the most advantageous?
A
  1. Resistance
  2. Elasticity
  3. Rigidity
    - The most beneficial materials of construction provide optimal elasticity and rigidity.
21
Q

Elasticity

A
  • Ability of a material to deform under stress - bending, elongation or compression - and to return to its original shape when the stress is removed.
  • Any material has a yield point beyond which it breaks or permanently deforms.
22
Q

Explain: ductile material vs brittle material

A

Ductile Material: Undergoes plastic deformation before breaking.

Brittle or fragile material: weak elastic limit and, without noticeable visible deformation, breaks under a load.

  • Less resistant than ductile materials, brittle materials are not very suitable for the construction of buildings.
23
Q

Rigidity

Why is it important?

A

Measurement of the compressive or tensile force that must be exerted on a material for it to reach its elastic limit.

The stiffness / rigidity of a material and the stiffness of its cross-section are very important when it comes to the relationship between span and deflection under load.

24
Q

The dimensional stability of a material determines what?

A

The degree of dimensional stability of a material subjected to variations in temperature and humidity determines how it will be shaped and joined to other materials.

25
3 types of structural systems & materials typically used for each
1 - LINEAR - columns & beams (steel/timber/concrete beams) 2 - PLANAR - walls & slabs (light wood/steel framing/masonry/concrete walls & slabs) 3 - COMPOSITE - columns/walls & beams/slabs
26
3 main types of shear strength in **high rise** construction
1 - CONVENTIONAL - shear walls/bracing & or rigid frames 2 - CORE - vertical circulation key to lateral strength 3 - TUBE - lateral bracing along perimeter
27
Best construction type for tall buildings in **seismic zones**
STEEL = **DUCTILE & LIGHT** **NOT CONCRETE** = HEAVY & BRITTLE
28
2 types of **dampening**
1 - **TUNED MASS DAMPER** - heavy mass on rollers towards the top of a tall building 2 - **BASE ISOLATION** - isolate the base from the ground so building can 'float' - prevents resonance
29
Effective structural building materials comprise of
* **Stiffness w Elasticity** * **Resist Dimensional Instability** due to Humidity & Temp.
30
Qualities of **wood** as a structural material
* small • renewable • flexible * light • exposed timbed \* GOOD IN COMPRESSION & TENSION
31
Qualities of concrete as a structural material
* Freedom of form • Naturally fire protected * Exposed structure • Inexpensive \* GOOD IN COMPRESSION - MUST BE **PAIRED WITH STEEL** REINFORCING FOR TENSION
32
Qualities of steel as a structural material
* Repetitious modular • Long spans * Light • Stiff & elastic
33
Describe the typical assembly for a **concrete slab**
TOP 1. 100min slab thickness 2. welded wire fabric reinforcement midway * controls thermal stress: shrinking /cracking * grid of bars needed for heavy floor loads 3. 6 mil poly 4. 50mm sand * soak up water during curing 5. 100mm min base course of gravel/crushed stone 6. stable uniformly dense soil * prevents capillary rise of groundwater
34
What are the 3 main **concrete joints**?
1. **_Isolation_** (aka expansion) * allows MVMT btwn concrete slab + adj. columns walls 2. **_Construction_** (also serve as control/isolation) * allows a place for construction to stop and start again @ later time * keyed or doweled 3. **_Control_** * ​​creates lines of weakness so cracking from tensile stress occurs along predetermined lines
35
Describe the typical **spacing of control joints**, and 3 common types.
typ. spaced **4500-6100(15'-20')** or where required: * irregular slab shape * openings 1. Sawn Joint 2. Premolded or metal strip inserted into concrete 3. Keyed Joint * prevent bond by applying metal or plastic joint material or applying curing agent to one side
36
Modulus of Elasticity
A stress to strain ratio of a given material. €
37
e = PL/AE
Total strain (deformation) of a material under a given load. ``` A = total area P = total force L = original length e = total strain ```
38
Moment
The tendency of a force to cause rotation about a point.