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05_PDD > OBJ 1.3 > Flashcards

OBJ 1.3 Flashcards

Determine the size of structural systems to meet project goals (U/A) You will need to be able to identify and develop structural systems, including calculating the size of some structural components based on the system type, system requirements, programmatic requirements, and other factors.

1
Q

Rigid Body Concept

A

In statics, rigid body concept means to ignore the small deformations of a structural member when loaded, in order to greatly simplify calculations and reduce errors.

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2
Q

Slenderness Ratio

A

Slenderness is a measure of the propensity of a column to buckle under loading. The slenderness ration is given as l/r where l is effective length and r is radius of gyration. It has no units because it is a ratio.

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3
Q

Moment of Inertia

A

A measure of a material’s resistance to buckling and bending.

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4
Q

Stiffness

A

Resistance to deformation.

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5
Q

Plywood vs. OSB

A

Both plywood and oriented strand board (OSB) are structural wood sheets made by gluing pieces of wood together. These engineered wood products are generally interchangeable, but each has different qualities. OSB is made from wood strands that are glued together in a cross-oriented pattern. Plywood is made from thin plies of wood bonded together. OSB is less expensive than plywood. OSB can soak up water more readily, especially at the edges where it can swell and permanently deform. When plywood gets wet, it also swells but then returns to its original size when dry. OSB weighs more and is less stiff than plywood. OSB is stronger in shear. Both can offgas and may contain formaldehyde.

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6
Q

Gauge

A

A unit of measurement of the thickness of a material, for example, steel studs; counterintuitively, a smaller gauge number indicates thicker metal, and a larger gauge number indicates a thinner metal.

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7
Q

Cofferdam

A

A watertight enclosure that is built in a body of water to allow construction to occur, such as when building bridges. The cofferdam is built and the water is pumped out to create a dry working environment for construction.

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8
Q

In Situ

A

“In situ” means “in place.” It is used to describe concrete that has been cast in place as opposed to precast concrete cast away from the site.

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9
Q

Maximum size of aggregate in a concrete mixture

A

Limited by size of the section and spacing of the rebar.

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10
Q

ASD vs. LRFD

A

ASD is Allowable Stress Design. LRFD is Load and Resistance Factor Design and is also called Ultimate Strength Design. Both are ways to calculate stress and, therefore, choose structural members. ASD treats live load and dead load the same and applies a factor of safety at the end of a calculation. LRFD treats live loads and dead loads differently, with a factor of safety applied to each. ASD is the “old” way of doing things and LRFD is the “new” way, but they are very similar and yield similar results. ASD is simpler, while LRFD is more nuanced.

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11
Q

Moment

A

Rotational force. It is the same thing as torque. It is a product of force multiplied by distance.

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12
Q

Ponding

A

When water from rain or snow melt is retained on a flat or semi-flat roof and, under the additional weight, the roof deflects, forming a bowl shape that enables the roof to retain even more water, and so on.

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13
Q

Importance Factor

A

In calculating seismic and wind loads, importance factor is a multiplier assigned to a building based on the building’s use. Essential facilities like hospitals and fire stations have the highest importance factor.

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14
Q

Creep

A

When a material moves or deforms slowly over time due to mechanical stresses; may or may not lead to failure.

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15
Q

T-Beam Action

A

In reinforced concrete design with a monolithic beam/slab condition, part of the slab becomes the compressive flange and contributes to the load resistance of the beam.

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16
Q

Force Couple

A

Two parallel forces of equal magnitude, but opposite sense, that are displaced by distance.

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17
Q

Liquefaction

A

When soils behave like liquids, losing the ability to support structures.

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18
Q

Thrust

A

The outward force exerted by one structural member onto another.

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19
Q

Abutment

A

The part of a structure that receives and supports thrust of an arch or vault.

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20
Q

Tie Rod

A

An iron or steel rod that serves as a structural tie, especially in an arched structure, to keep the lower ends from spreading.

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21
Q

Clear Span

A

The distance between the inside faces of the supports of a span.

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22
Q

Effective Span

A

The distance between the centerlines of the supports of a span.

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23
Q

Haunch

A

A thickened or deepened part of a beam located at one end to create greater resistance to movement. In other words, a haunch puts more “meat” at the joint where stresses are greatest, instead of providing depth throughout the beam, where it is wasted.

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24
Q

Zero Force Member

A

A member in a truss that takes no load.

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25
Q

Woods for Structural Use

A

Fir, pine, spruce, redwood, cedar, hemlock, and larch.

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26
Q

Larger sections of wood shrink proportionately ________ (less/more) than smaller sections of lumber.

A

Less.

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27
Q

Wood is strongest when loaded _________ (perpendicular/parallel) to the grain.

A

Parallel; however, wood is often loaded perpendicular to the grain, as in a beam.

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28
Q

Dressed Lumber

A

Lumber that has been surfaced by a planar.

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29
Q

Rough Lumber

A

Lumber that has been cut into board shapes and sizes but has not been planed.

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30
Q

Dimension Lumber

A

2-by and 4-by lumber; joists, rafters, studs, etc.

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31
Q

Timber

A

Lumber 5 inches or more in least dimension; beams, posts, purlins, etc.

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32
Q

Section Modulus

A

A property of a material’s cross-section, it is the moment of inertia divided by the distance from the neutral axis to the extreme fiber.

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33
Q

Engineered Wood

A

Any of various products manufactured by taking strands, veneers, fibers, or other parts of wood and bonding them together for a composite product; includes plywood, OSB, glulams, paralams, microlams, LVLs, particleboard, and cross-laminated timber.

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34
Q

Mild Steel

A

Rolled structural steel. Typically referred to as “I beams”.

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35
Q

Principal disadvantages of steel

A
  1. Loss of strength when exposed to fire
  2. Rusting
  3. Cost
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36
Q

Principal advantages of steel

A
  1. Immense strength
  2. Flexibility (can sway under seismic loads)
  3. Ductility (deforms before fracturing)
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37
Q

Steel Shapes

A

Bar, plate, rod, tube (square), pipe (round), structural shapes such as wide-flange, channels, and angles.

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38
Q

Cold Rolled

A

Steel that has been rolled at room temperature. It has closer dimensional tolerances and smoother surfaces than hot-rolled steel and is more expensive. Cold rolled steel is first hot rolled into a general shape.

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39
Q

Hot Rolled

A

Steel that has been shaped through a roller at high temperatures and then cooled. It is easier to form and less expensive than cold rolled steel.

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40
Q

Ways to shape metal

A

Rolling, extruding, casting, forging, stamping, and drawing.

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41
Q

How to read a wide-flange steel shape designation.

A

For W 12 x 26, W is the shape (W stands for wide-flange), 12 is the depth in nominal inches (actual depth of this section is 12.22 inches), 26 means the steel shape weighs 26 pounds per linear foot.

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42
Q

Steel-Bearing Plates

A

Steel beams typically sit on steel bearing plates. The plate provides a level surface for bearing, helps distribute the load over a larger area, and helps with setting the beam at the proper bearing height.

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43
Q

Built-Up Section

A

Forms a structural member by combining two or more structural steel shapes.

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44
Q

Pipe and tube structural steel is best for columns in ______ (single-story/multi-story) buildings.

A

Single story. This is because the spanning members can sit on top of the columns and not have to connect to the side. Wide-flange beams are most useful for multi-story buildings, where beams are attached to the sides of columns.

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45
Q

Free-Body Diagram

A

A diagram of a body that shows the external forces with the magnitude and angle of all the forces. Also called a force diagram.

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46
Q

Normal

A

“Normal” means perpendicular in physics.

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47
Q

Area of a Circle

A

A = π r2.

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48
Q

External loads on a body cause it to elongate or shorten. What is this called?

A

Deformation or strain.

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49
Q

Resistance to deformation is due to _______.

A

The modulus of elasticity, which is the measure of a material’s stiffness.

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50
Q

The _______ is the point at which a material continues to stretch with no increase in load.

A

Yield point.

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51
Q

Hooke’s Law

A

States that stress is proportional to strain, up to the elastic limit.

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52
Q

Young’s Modulus

A

A measure of the stiffness of a material; also known as the elastic modulus or modulus of elasticity.

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53
Q

The cable of a uniformly supported suspension bridge hangs in the form of a(n) ________.

A

Parabola.

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54
Q

Circumference of a Circle

A

C = 2πr.

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55
Q

Cast Iron

A

A brittle ferrous metal with large amounts of carbon and impurities. Pipes are sometimes made from cast iron.

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56
Q

Wrought Iron

A

Ferrous metal with low carbon content. Malleable, ductile, and corrosion resistant. Can be welded. The Eiffel Tower is made of wrought iron.

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57
Q

Area of a Triangle

A

A = 1/2 x base x height.

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58
Q

Considerations of the effects of wind

A

Magnitude of sustained velocities; duration of gusts; gust effects such as swirling; and prevailing wind direction.

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59
Q

Resonant Loading

A

Winds can make buildings oscillate side to side, the forces of which are called resonant or oscillating loads.

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60
Q

Wind speeds are ______ (lower/higher) at the base of a building.

A

Lower.

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61
Q

Wind Tunnel Testing

A

Simulates real-world conditions to model acute wind behavior on an object.

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62
Q

Story Drift

A

Horizontal deflection of a single story relative to the story above or below. Story drift is due to wind or earthquake forces. Not specified in the IBC but often limited to 0.005 or 0.0025 times the story height.

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63
Q

Uplift

A

Buildings must resist the uplifting force of wind. Uplift may affect the whole building or just parts of it.

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64
Q

Special Wind Region

A

Wind is affected by local topography and climate such as that near open water or mountains. These areas often have local wind design considerations.

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65
Q

Restoring Moment

A

Resists overturning moment

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66
Q

Wind Speeds

A

10 mph: mild breeze;
25 mph: stiff breeze;
50 mph: strong gale

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67
Q

Drag

A

Because air is a fluid, wind blowing around a building has a drag effect.

68
Q

General effects of wind on objects

A

Big Three: 1. Direct Positive Pressure
2. Drag
3. Negative Pressure (aka, suction on the leeward side)
Also rocking effects (wind is not a constant velocity), harmonic effects (vibration, flutter, whistling), and clean-off effect (the impact of wind on protruding objects such as equipment, canopies, and signs). Wind damage can be local or total. Damage can be collapse, roll-over, or uplifting. Factors include the nature of the wind, nature of the object (size, shape, period, stiffness of surfaces, and strength of connections), and nature of the environs (sheltering and funneling).

69
Q

Specific effects of wind on objects

A

Inward pressure on exterior walls, suction on exterior walls, pressure on roof surfaces (inward and outward), overall horizontal force (the reason we need lateral resistance), horizontal sliding force (the building sliding off the foundation), overturning, wind design for specific building parts such as protruding elements, harmonic effects, effect of openings and “cups” (particularly band shell structures and similar forms), and torsional effects due to asymmetry. In addition to buildings, freestanding exterior walls and signs must be designed for wind resistance.

70
Q

Simplifying wind design

A

Most buildings are box-shaped, which results in a typical aerodynamic response. Most buildings have closed, relatively smooth surfaces. Most buildings are snug to the ground where the earth creates drag. Most buildings are relatively stiff, and there is a relatively limited range of building periods.

71
Q

Buildings that require a more thorough investigation of the impact of wind

A

Tall structures, elevated structures where wind can pass underneath, flexible structures such as fabric structures, large overhangs, and unusual aerodynamic shapes. More analysis is typically needed for structures with these qualities and wind tunnel testing might need to be performed.

72
Q

Wind Exposure A, B, C, and D

A

Exposure A is legacy.

Exposure B is for sites in urban and suburban areas, wooded areas or other areas where there is terrain with numerous closely spaced obstructions.

Exposure C is for sites of open terrain, such as flatlands and grasslands.

Exposure D is for sites next to open water, unbroken ice or salt flats.

73
Q

Overturning Effect

A

Can apply to the building as a whole or parts.

74
Q

True or false? A heavy building is a disadvantage in terms of wind design.

A

False. Heavy buildings resist overturning, uplift, and sliding.

75
Q

Fastest Mile

A

The old way of measuring wind speeds (prior to 1998). Now it is the 3-second gust.

76
Q

3-Second Gust

A

The 3-second gust speed at 33 feet above the ground in exposure category C is used to determine the basic wind speed (V) for building design.

77
Q

Highest recorded surface wind speed

A

About 300 mph (during a tornado).

78
Q

Most important tables in the code to know for PDD case studies

A

Table 503 Allowable Building Heights and Areas
Table 601 Fire-Resistance Rating Requirements for Building Elements (hours)
Table 602 Fire-Resistance Rating Requirements for Exterior Walls
Table 716.5 Opening Fire Protection Assemblies, Ratings, and Markings

79
Q

Most important chapters in the code to know for PDD case studies

A

Chapter 3 Use and Occupancy Classification
Chapter 4 Special Detailed Requirements Based on Use and Occupancy
Chapter 5 General Building Heights and Areas
Chapter 9 Fire Protection Systems
Chapter 10 Means of Egress
Chapter 11 Accessibility
Chapter 12 Interior Environment

80
Q

Slab on Grade

A

Just as it sounds, it is a placement of a concrete floor slab directly over a prepared base set on prepared earth. Welded wire mesh helps keep it from cracking.

81
Q

What are some key items to consider for wood structures?

A
  • Keep it dry
  • Requires ventilation
  • Keep joists a minimum of 18” away from the ground
  • Keep girders a minimum of 12” away from the ground
  • Any wood within 6” of the ground must be treated
  • Fire stops are required for multi-story wood construction
82
Q

Split Slab Construction

A

In contrast to a solid slab, which acts as both the structural support and traffic surface for a floor, a split slab separates these two functions into two parts. The lower part is a structural slab, which carries the necessary loads. A waterproofing membrane is placed above this element to separate it from the topping slab. The topping slab is then placed on top of the waterproofing membrane. Split slab construction allows the waterproofing layer to be protected from traffic by the topping slab.

83
Q

Cold-Formed Metal Framing

A

Steel metal studs that are manufactured by bending sheet metal at room temperature; contrasts with hot-rolled steel. Cold-formed metal framing, also called light gauge metal framing, is used as a non-combustible alternative to wood studs.

84
Q

Two main classifications of loads

A
  1. Gravity loads 2. Lateral loads
85
Q

Examples of gravity loads

A

Dead load, live load, rain load, and snow load.

86
Q

Examples of lateral loads

A

Wind load, earthquake load, and other lateral loads.

87
Q

Design Wind Speed

A

Used in determining the design wind loads on buildings. If the basic wind speed has a 2% annual probability of being exceeded, this is a 50-year recurring value.

88
Q

Factors that affect wind loads

A
  • Height above ground
  • Exposure classification of the site
  • Topography of the site
  • Enclosure classification of the building
  • Importance of the building’s occupancy
89
Q

Site Exposure Category B

A

Urban and suburban areas, wooded areas or other terrain with numerous closely spaced obstructions.

90
Q

Site Exposure Category C

A

An open country or grassland location.

91
Q

Site Exposure Category D

A

A flat, unobstructed site facing a large water body.

92
Q

Partially Enclosed Structures

A

These include buildings in which the area of openings in one wall is much larger than that of the remaining walls, like for airport hangars or warehouses with docks.

93
Q

Escarpment

A

A long, steep slope, separating areas of land at different heights. It increases wind speed, and thus wind loads on buildings.

94
Q

Soil Liquefaction

A

This occurs in water-saturated, sandy soils where particle sizes of sand are relatively uniform in size. This results in a loss of foundation support for buildings with construction on top.

95
Q

Richter Scale

A

Scale most commonly used to measure the intensity of earthquakes.

96
Q

Tectonic Plates

A

Earth’s crust is divided into several individual segments and these segments float on a molten mantel below and are constantly in motion relative to each other.

97
Q

Factors that affect earthquake loads

A
  • Ground motion
  • Building mass and ductility of structural frame
  • Type of soil
  • Importance of buildings
98
Q

Material weight relative to earthquake loads

A

Lighter buildings attract smaller earthquake loads; concrete and masonry framed buildings attract larger loads than those made from wood or steel.

99
Q

True or false? Buildings are designed to resist wind and earthquake loads.

A

False. Buildings are designed to wind or earthquake loads, whichever causes the greatest effect. In regions with low seismic activities, buildings are designed for wind.

100
Q

Seismic Risk Category IV

A

Most important or hazardous buildings including: police stations, water-treatment facilities, and fire stations. Reference IBC Table 1604.5.

101
Q

Seismic Group II

A

Important or hazardous buildings: schools, health-care facilities, and power-generating stations.

102
Q

Seismic Group III

A

Normal buildings that do not belong in group I or II.

103
Q

Tributary area of a building component

A

Area of a building that contributes to a load on a specific component, like a column.

104
Q

Which direction is earthquake load generally directed in?

A

Horizontal; lateral bracing is required to resist this.

105
Q

Brittle Material

A

A material that deforms little before failure. This type of material is generally stronger in compression than in tension.

106
Q

Buckling

A

Type of failure that results in the sudden bending of a slender structural member subjected to excessive loading.

107
Q

Diagonal Brace

A

Linear, diagonal stiffening element against lateral loads.

108
Q

Brick Ledge

A

Depressed portion of a concrete foundation to support the first story of brick veneer.

109
Q

Beamless Floor

A

A reinforced-concrete slab supported directly on columns without supporting beams.

110
Q

Centering

A

Temporary framework for constructing an arch, vault, or dome.

111
Q

Backup Wall

A

Load-bearing or non-load-bearing wall to which exterior cladding is adhered or anchored.

112
Q

Basic Wind Speed

A

Peak 3-second gust wind speed with a 50-year recurrence interval, used to determine wind loads on a building.

113
Q

Grade Beam

A

A reinforced-concrete beam constructed at ground level.

114
Q

Elevated Slab

A

An above-ground floor or roof slab, supported on columns and/or beams and forming an integral part of a structural frame.

115
Q

Lintel

A

A beam that spans over a door or window opening.

116
Q

Insulating Concrete

A

Lightweight concrete consisting of portland cement, water, and expanded aggregate, primarily used as low-slop roof insulation.

117
Q

Heavy Timber

A

Sawn lumber with both cross-sectional dimensions greater than 5”.

118
Q

Hollow Structural Section

A

Square or rectangular tubular steel section used as columns or beams in a steel frame structure or as components of a steel truss.

119
Q

One-Way Slab

A

An elevated reinforced concrete slab where most of the load on the slab is carried to the supporting beams in one direction; a four-sided, supported rectangular slab whose length is greater than or equal to twice its width.

120
Q

Open-Web Steel Joist

A

A standardized, prefabricated, steel parallel chord truss used to span between beams, larger joists, or trusses.

121
Q

Pilaster

A

A column formed by thickening an area of a masonry or concrete wall.

122
Q

Primary Reinforcement

A

Steel reinforcement in a one-way concrete slab oriented in the direction that carries most of the loads.

123
Q

Secondary Reinforcement

A

Reinforcement in a one-way concrete slab placed perpendicular to primary reinforcement.

124
Q

Shelf Angle

A

Steel angle attached to a spandrel beam or a load-bearing wall to support masonry veneer.

125
Q

True or false? The level of mathematics in structural engineering is usually quite rigorous, requiring the use of high-level mathematics such as calculus and differential equations.

A

False. Structural calculations are usually done with arithmetic, algebra, and the occasional trigonometry or elementary calculus. Calculations that are more complex are done with computer assistance.

126
Q

Internally Braced Frame

A

Shear walls, diagonal bracing, and knee braces that are used to resist lateral loads from within a structure.

127
Q

Externally Braced Frame

A

The use of external sources of lateral bracing such as guylines, struts, and buttresses.

128
Q

Eccentrically Braced Frame

A

When one or both ends of the lateral bracing for a structure do not join the end points of other members. Eccentric bracing is the opposite of concentric bracing. Knee bracing is an example of eccentric bracing.

129
Q

Will braced frame members work in tension, compression, or both?

A

Both.

130
Q

True or false? Roof slabs are typically designed to be stronger than floor slabs because of the added forces of wind and snow.

A

False. Roof structures are typically lighter construction than floor structures.

131
Q

Three-Hinged Structure

A

A gable roof where members are supported only by one another at the top is called a three-hinged structure. It requires additional support, such as collar ties or ceiling joists, to keep the rafters from collapsing.

132
Q

Collar Tie

A

In a small, pitched roof formed by two planes of inclined rafters, collar ties are the horizontal framing members that tie the rafter together near the top to reduce outward thrust on the rafters.

133
Q

Ridge Beam

A

In a gabled roof, a ridge beam is the horizontal member that the upper end of rafters can be supported on, eliminating the outward thrust of the rafters on the lower walls.

134
Q

Wind Speed Maps

A

Published by the American Society of Civil Engineers (ASCE) and incorporated into building codes, wind speed maps are continuously updated. The current version is the ASCE 7-10.

135
Q

True or false? Concrete and reinforcing steel have similar coefficients of thermal expansion.

A

True.

136
Q

Effective Length Factor (K Factor)

A

The effective length factor (K) is a coefficient for approximating the length of a column that will actually buckle based on end conditions. The effective length can be longer, shorter, or the actual length, depending on the rigidity of the supports. If the K factor is below 1.0, then the structure has a greater ability to carry forces, and if the K factor is above 1.0, then the structure has a lesser ability to carry forces. For example, fixing both ends of a long column has a K factor of 0.5, which reduces its effective length by half.

137
Q

How much does normal weight concrete weigh? Lightweight concrete?

A 
Normal = 150 pcf
Lightweight = 90–120 pcf
138
Q

Lateral Load Resisting System

A

The structural system responsible for countering wind and seismic loads on a building. The vertical portion is often composed of moment frames, braced frames, shear walls, or a combination of these. A common path of the lateral load is from the façade to the floor plates (which act as diaphragms), to the vertical lateral load resisting system, to the foundations.

139
Q

Prestressed Concrete

A

A type of concrete construction in which the concrete is “prestressed” after it is poured, but before any additional load is placed on it. This results in thinner slabs and beams that have a smaller cross-sectional area than traditional concrete construction.

140
Q

Deep Foundations

A

Foundations that penetrate deep into the Earth’s surface. Unlike shallow foundations, deep foundationseither use friction to transfer loads or they bear directly on the bedrock below. Piles and caissons are typicaldeep foundations. Piles are made of steel or timber and are driven into the ground using a pile driver.Caissons are constructed with reinforced concrete and are cast in place.

141
Q

Purlin

A

Horizontal structural members that support roof/floor load and transfer them to perpendicular beams; typically shallower than traditional beams.

142
Q

Dunnage

A

Nonpermanent structural platform for mechanical equipment used to distribute weight more evenly over an area, typically seen on a roof.

143
Q

Rooftop Curb

A

Permanent built-up structure to support roof top units; typically seen on roofs and are flashed and sealed to prevent water intrusion.

144
Q

Bond Beam

A

A reinforced horizontal beam of concrete or masonry frequently placed in walls at foundations and below roofs.

145
Q

Rebar

A

Reinforcing bar. Provides tensile strength to reinforced concrete. The bar’s number is the diameter of the bar in 1/8s of an inch. For example, a #5 bar is 5/8” inches in diameter.

146
Q

Spread Footing

A

A type of shallow foundation where axial loads are distributed in a uniform manner under the footing. Allowable bearing pressure necessary to resist the load determines the size of the footing.

147
Q

Wall Footing

A

Continuous strip of concrete below a foundation wall that spreads the load of the building over a larger area. These are used in shallow foundation systems and are among the most common types of footings.

148
Q

Combined Footing

A

Foundation system used when columns are located in close proximity to one another or too close to a property line; a footing is poured for all of them together.

149
Q

Mat Foundations

A

A continuous foundation system that is used when soils are weak. They cover the entire building footprint to distribute heavy loads, making it a very expensive system.

150
Q

Pile Foundations

A

Foundation system that uses piles driven or drilled deep into the earth; typically used when soil is unsuitable for spread footings and the foundation needs to transmit loads through soil to a stronger bearing surface below.

151
Q

Friction Pile

A

A type of pile foundation used in softer soil that uses friction to transfer loads across the full height of the pile. The piles do not reach down to harder surfaces below the surface and thus can be driven shallower. Bearing capacity is limited by the weaker of either the pile or soil strength.

152
Q

Socketed Caissons

A

Type of foundation system used where deep foundations are required; holes are drilled deep into the earth and into rock or firm strata, and concrete is poured; bearing capacity is dictated by end-bearing and frictional forces.

153
Q

End-Bearing Piles

A

Type of foundation system in which a pile reaches down far enough to a strong layer of soil or rock on which the end rests. Loads are thus transferred to the hard soil at this bearing point.

154
Q

Belled Caisson

A

Type of foundation system in which holes are drilled into the earth and concrete is poured; for use when deep foundations are required. The ends of these elements are made wider and belled to distribute loads more evenly in the firm strata. This is used in areas where firm soil lies beneath soft or expansive upper soil.

155
Q

Transfer Beam

A

A structural beam used to transfer the loads from a column resting on it to its supports. Transfer beams are typically deeper and are used when column grids cannot align between different levels.

156
Q

Bundled Tube System

A

A lateral load-resisting system used in high-rise construction. In a bundled tubes system, thinner structural tubes act together to create a more efficient system. Similar to cantilevered tubes, bundled tubes are treated as a rigid connection perpendicular to the ground. The Willis Tower (formerly Sears Tower) in Chicago is an example of a bundled tube.

157
Q

Cantilevered Tube

A

A lateral load resisting system used in high-rise construction. Cantilevered tubes place a rigid structural system on the outside of the building and structurally treat it as a fixed connection, perpendicular to the ground. This simplifies the calculations required to size internal members. The John Hancock Center in Chicago, IL is a great example of a cantilevered tube.

158
Q

Composite Decking

A

A type of composite construction that combines concrete and steel construction. Composite decking uses a fluted metal deck as the formwork for a concrete floor. This combines the tensile strength of steel with the compressive strength of concrete. Commonly, shear studs are used to connect the composite deck to steel beams below.

159
Q

Shear Stud

A

A steel element that is welded to the top of a steel beam and extends into the concrete portion of a composite deck. Shear studs help transfer stresses between the two elements and create a more efficient structural system.

160
Q

Dr. Fazlur Khan

A

A pioneer in high-rise design, Dr. Khan was one of the lead structural engineers for Skidmore, Owings & Merrill in the 1960s and 1970s. He is best known his work with tube structural systems for tall buildings. His work on the Willis Tower (formerly Sears Tower) and the John Hancock Center in Chicago exemplify his theories.

161
Q

Yield Strength of Steel (Fy)

A

A36 Steel - Fy = 36 ksi; A992 Steel - Fy = 50 ksi.

162
Q

Tensile Strength of Steel (Fu)

A

A36 Steel - Fu = 58 ksi; A992 Steel - Fu = 65 ksi.

163
Q

Modulus of Elasticity of Steel (E)

A

29,000 Kips/Square inch (ksi).

164
Q

Gusset Plate

A

A thick triangular-shaped piece of steel used to strengthen a structural connection such as the joint between a beam or brace and a column.

165
Q

Castellated Beam

A

A beam, typically a wide flange, split in two with a specific cut pattern, in order to be reassembled to have pass throughs for piping, conduit, or other MEP systems. The reassembled beam is deeper than the original.

(insert image)

166
Q

What are the three different grades found in glulam beams?

A

Industrial: appearance is not a concern; Architectural: appearance is a concern; Premium: highest grade available, appearance is of high concern.

05_PDD (17 decks)

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