Structural Behaviors Flash Cards For Exam 1 2008

Front 1

What is Stability?

Back 1

Stability is equilibrium over time. Equilibrium must be steady, permanent and lasting.

Front 2

Force-

Back 2

any action thats applied to objects (buildings). EX) wind loads

Front 3

External forces-

Back 3

referred to as loads.
(Gravity loads, wind loads, earthquakes, miscellaneous loads)

Front 4

Internal forces-

Back 4

referred to as stress.
(tension, compression, shear, bending, buckling, torsion.)

Front 5

* Stress-

Back 5

the push or pull on an element divided by the area its applied to. (internal forces)

Front 6

tension-

Back 6

the pulling action on a beam or building. (makes it longer)

Front 7

compresison-

Back 7

a pushing action on a beam or building. (makes it shorter and fatter in the middle)

Front 8

shear

Back 8

made up of tension and compression, a sliding action. (one object slides down another object.)

Front 9

lateral loads-

Back 9

wind loads and earthquakes

Front 10

bending-

Back 10

happens when the top is in compression and the bottom is in tension. (beam bends down, top is shorter and bottom longer)

Front 11

buckling-

Back 11

like bending, happens when the top is in compression and the bottom is in tension. (beam bends down, top is shorter and bottom longer), but vertically . (tall and thin columns do this)

Front 12

Torsion-

Back 12

Twisting action as a result of heavy loads on one end.

Front 13

Strength-

Back 13

the capacity to resist tension and compression.

Front 14

strain-

Back 14

tiny changes in length due to tension or compression divided by the original length.

Front 15

Elastic behavior-

Back 15

with elastic deformation the change in shape vanishes rapidly when the load is removed.

Front 16

Hooke's Law and Linear Elasticity-

Back 16

Deformations increase in proportion to the load.

Front 17

What is the strongest material in tension and compression?

Back 17

Steel (Tension- 20,000 to 33,000) (Compression-10,000 to 22,000)

Front 18

What is the weakest material in tension and compression?

Back 18

Masonry (Tension- 50 to 100) ( Compression- 200 to 400)

Front 19

Elastic Limit-

Back 19

Point when the material will begin to change length at a faster ration than the applied force. (point above which there will be permanent deformation even if the force is removed)

Front 20

Plastic Behavior-

Back 20

Deformations are permanent

Front 21

Yield Point-

Back 21

The point at which the material continues to deform with very little increase in load.

Front 22

Ultimate strength-

Back 22

Unit stress just before rupture or pound/SQ inch a material will carry before it breaks.

Front 23

Ductile Failure-

Back 23

When a material displays permanent deformation before a failure (warning).

Front 24

Elastic Failure/Brittle Failure-

Back 24

material behaves elastically up to the breaking point.

Front 25

* When picking a structural material you want 3 things...

Back 25

1. Strength
2. elastically
3. Plastically (Ductile failure)

Front 26

Transition Temperature-

Back 26

Temperature at which a material changes from elastic to plastic behavior.

Front 27

Modulus of Elasticity-

Back 27

Characteristic ratio of stress to strain. Measure of a materials resistance to deformation or stiffness.

Front 28

What does E=?

Back 28

E= unit stress/ unit strain

Front 29

safety factor-

Back 29

The number of times a structure could be over loaded before collapse.

Front 30

Moment-

Back 30

the tendency of a force to cause rotation about a point. Product of the force times the distance to the point about which it is acting. (Units- foot lbs, inch lbs or kip-feet)

Front 31

Formula of MOMENT-

Back 31

Force X Distance

Front 32

Properties of sections-

Back 32

The point on a planar surface that corresponds to the center of gravity. Point at which the mass of the body can be considered concentrated.

Front 33

Centroid-

Back 33

the point on a planar surface that corresponds to the center of gravity (point at which the mass of the body can be considered concentrated)

Front 34

Moment of Inertia-

Back 34

Measure of the bending stiffness of a structural member's cross-sectional shape. Dependent on the area of a section and the distance of the area from the neutral axis.

Front 35

Mass & Carved Monumental Structures-

Back 35

Carve away from cave (dont have to worry about structure)

Front 36

Post & Beam Construction-

Back 36

Columns spread out as top to reduce shear and expand down to be bigger at bottom so the weight could be distributed. (most of what you do in modern arch.)

Front 37

Post and Beam: Egypt-

Back 37

columns as structural and decorative element. (Carved out of solid piece of stone

Front 38

Post and Beam: Greece-

Back 38

Expression of statical function. Carved sections of column and put them together. Hollow out the drums so that they can fit together better)

Front 39

Roman Timber Trusses

Back 39

Romans built wooden bridges

Front 40

What are they three vault systems?

Back 40

1. Arches and barrel vaults
2. Groin vaulting
3. Roman vault systems

Front 41

Arches and barrel vaults-

Back 41

stone buildings dont burn down. Stone arches bc loads are resistant in compression. Arches put together create barrel vaults.

Front 42

Groin Vaulting-

Back 42

two intersecting vaults, instead of resting on a wall they rest on points.

Front 43

Roman vault systems-

Back 43

romans perfected vaulting. Interlocking stones and arches instead of stacking

Front 44

Domes-

Back 44

make with stone. Problem: top is n compression while bottom in in tension. Have it ticker at bottom and thiner on top.

Front 45

What is the oldest standing dome?

Back 45

the Pantheon

Front 46

What types of mathematics did Egypt, Greece and Euclid use in Ancient Architecture?

Back 46

Egypt- linear and angular measurements.
Greece- Property of right angles (Pythagorus)
Euclid- basis of modern geometry

Front 47

What are the 5 types of Ancient Architecture?

Back 47

1. Mass & Carved Monumental Structures
2. Post and Beam Construction
3. Roman Timber trusses
4. Vault systems
5. Domes

Front 48

Two types of Medieval Architecture-

Back 48

1. Islamic and Byzantine Refinements of vault and dome construction
2. Gothic Structural Developments

Front 49

Pointed Arches-

Back 49

11th and 12th century but early as 7h century. Allows you to have rectangular bays.

Front 50

Squinches-

Back 50

and arch built across the interior corner of 2 walls to serve as a foundation for a diagonal element.

Front 51

Pendentives-

Back 51

A spherical, triangular surfaces used to merge the circular shape of a dome with a square base.

Front 52

Double-Layer domes-

Back 52

uses a double layer dome of timer construction.

Front 53

Pleated domes

Back 53

folding makes it stronger..

Front 54

Groined vaulting with ribs-

Back 54

when you tub something with joint between them it gives them strength.

Front 55

Flying Buttresses

Back 55

instead of having thick walls they pull the line of thrust away from the building.

Front 56

Fan vaulting-

Back 56

A vault of conoidal form with ribs that spread out from the spring point in a manner which suggests the appearance of an open fan.

Front 57

1st law of motion-

Back 57

body at rest will remain at rest unless a force is applied. (Sir Isaac Newton 17th century)

Front 58

3rd Law of motion-

Back 58

for every action there is an equal and opposite reaction.

Front 59

Industrial revolution: Steam power and cast iron-

Back 59

development of steam engine- first effective machine or producing power mechanically. Cast iron- produced by china in 6th century. strong in compression but brittle.

Front 60

steel-

Back 60

stronger, can be thinner, fails ductually rather than brittlely

Front 61

Reinforced concert: endoskeleton structures-

Back 61

portland cement (1824) reinforced concrete, put steel in it to make it stronger.

Front 62

Plastics-

Back 62

can be strong as steel in compression and tension

Front 63

thin shell-

Back 63

can span long areas with little materials

Front 64

suspension systems (Roebling)

Back 64

1st used in bridges.

Front 65

Pneumatics-

Back 65

air inflated structures

Front 66

Soil Mechanics-

Back 66

determine the baring capacities before we build on them (leaning tower of pisa)

Front 67

What are 5 theories of Modern Architecture?

Back 67

1. Soil Mechanics
2. Logarithms
3. Architectural Education
4. Civil Engineering Profession
5. digital calculation

Front 68

Loads-

Back 68

forces acting on structural components

Front 69

Effects of loads-

Back 69

stress, deformation and deflection. If it gets high enough you get cracking or sagging.

Front 70

Uniform and Concentrated loads-

Back 70

Uniform ex- a foot stepping down
concentrated ex- a foot with a snow shoe so the weight is distributed over a larger area.
(Some loads are assumed to be uniform even though they are not (ex? PPL)

Front 71

Dead Loads-

Back 71

THe vertical loads due to the weight of the building and any permanent equipment. anything permeant in the building/ building itself.
EX) structure, ceiling and floor ect.

Front 72

Calculating dead loads-

Back 72

paradox of structural design to size the structure systems you must know the weight of the structural systems.
Volume X specific weight.

Front 73

Live loads-

Back 73

loads imposed on the building by its particular location. use and occupancy. EX) People, furniture, moveable equipment, stored goods, snow and rain. etc.

Front 74

Mandatory minimum live loads-

Back 74

established by building code, safety: Based on the worst loading conditions during the life of the building. Assumes the worst effect of varying live loads can be represented by uniform load evenly spread over the surface of the floor. EX) new york apartment- 40 lbs/s

Front 75

Live load reductions-

Back 75

highrise construction: 60%. Structural members that carry more than 150 s.f. except assembly spaces, loads greater than 100 pounds etc...

Front 76

Wind loads-

Back 76

lateral loads- horizontal
primary effects- lateral forces on cladding and structure.
negative pressure- leeward side, sides parallel to wind, uplift on roof.
localized effect- corners, eaves, parapets.

Front 77

fastest mile wind-

Back 77

average speed of a column of air one mile long that passes over a given point. measured with a anemometer

Front 78

extreme fastest wind mile-

Back 78

highest fastest mile wind speed recorded in a certain time period. (50 yrs)

Front 79

Gradient height-

Back 79

metropolitan areas- 1500 ft, suburban areas- 1200 ft, open country- 900 ft.

Front 80

Determining wind pressure: Combined height, exposure and gust factor-

Back 80

the higher up you go the more you have to take into account the wind. Design to flat land and tree areas are different.

Front 81

Pressure coefficient-

Back 81

takes into account the differing effects of wind on various parts of the building.

Front 82

wind stagnation pressure at standard height of 30 ft-

Back 82

vary pressure at a height

Front 83

importance factor-

Back 83

not all buildings have to be built to the same standards, takes into account the requirement of safety for essentials.

Front 84

What are the three designs of wind resisting structures?

Back 84

1. Plan shape
2. Diaphragm design
3. framing methods

Front 85

Plan Shape-

Back 85

rectangular shapes have a tendency to block more of the wind than round or tapered shapes. Triangle shapes are more aerodynamic.

Front 86

Diaphragm design-

Back 86

Uses floor construction like a giant beam to stiffen structure against a wind load.

Front 87

What are the framing methods?

Back 87

1. moment resisting frames
2. Knee bracing
3. X-bracing
4. K- Bracing
5. Portal frames
6. Framed tubes
7. trussed tubes

Front 88

Moment-resisting frames

Back 88

connections are used between columns and beams useful for buildings larger than 30 ft.

Front 89

Knee Bracing-

Back 89

economical way to provide rigidity to a steel frame. easily concealed in a suspend ceiling.

Front 90

K-Bracing-

Back 90

results in less horizontal drift than X bracing bc members are shorter and therefore elongated less under stress.

Front 91

X-Bracing-

Back 91

one of the most common types of lateral bracing for tall structures.

Front 92

Portal Frames-

Back 92

composed of trusses at each floor level with knee braces connecting the trusses to columns.

Front 93

Framed-tubes

Back 93

creates a large hollow tube cantilevered from the gravel.

Front 94

cantilevered-

Back 94

A projecting structure, such as a beam, that is supported at one end and carries a load at the other end or along its length

Front 95

Trussed tubes-

Back 95

combination of rigid frames and diagonal braces on the exterior wall.

Front 96

Shear wall-

Back 96

concrete shear walls transmit the lateral forces to the foundation. Frequently used because concretes shear walls can easily be part of cores. H or T shaped sections provide rigidity in both directions.

Front 97

drift-

Back 97

generally limited to 1/500th of the building height/ Drift of adjacent floors must be limited to 0.0025 X the floor height.

Front 98

What are the different types of connections?

Back 98

angle bracket connection, structural lee, wielded connection, studs bracket.

Front 99

Earthquake loads: Dynamic analysis-

Back 99

have to use computers in analysis. look at how our buildings would respond to a historic earthquake. Used in tall buildings.

Front 100

Static Analysis-

Back 100

Equivalent lateral loads based on 6 factors.

Front 101

**What are the 6 static analysis factors?

Back 101

1. Z factor- earthquake zone
2. L Factor- importance of building type
3. K Factor- structural system
4. C Factor- building acceleration
5. S Factor- subsoil conditions
6. W Factor- total Dead Load

Front 102

Plate Slippage-

Back 102

plate movement causes an up and down motion.

Front 103

Hypocenter-

Back 103

the point where stress is maximum, several miles below the surface.

Front 104

Epicenter-

Back 104

point on the earth surface directly above hypocenter.

Front 105

Richter Scale-

Back 105

Measures magnitude of energy in the earthquake.

Front 106

What is the Richter scale range?

Back 106

0 (low end) to 9 (highest ever recorded)

Front 107

Logarithmic Scale-

Back 107

each scale number represents about 32 times the amount of energy as the number below it.

Front 108

Modified Mercalli Intensity scale-

Back 108

Subjective rating based on observed damage.

Front 109

Modified Mercalli Intensity Scale Range-

Back 109

I (not felt except under especially favorable circumstances) to XII (damage nearly total). Measures effect on ppl and buildings- used to determine seismic zones.

Front 110

Seismic Zones-

Back 110

Zone 0- no damage
Zone 1- minor damage (Detroit)
Zone 2- moderate damage
Zone 3- major damage
Zone 4- Those areas with Zone 3 determined by the proximity to major fault systems (California).

Front 111

What are the effects of Earthquakes on buildings?

Back 111

1. Shear force at base of building (Buildings tip over or building rotates)
2. Oscillation: Dependent on mass and stiffness. (Accelleration of the ground causes building to osculate. Flexible, long period.)

Front 112

Ductility-

Back 112

greater ductility of a building, greater its capacity to absorb energy. Steel is ductile, masonry and concrete is not.

Front 113

Shear Walls-

Back 113

vertical structural elements that resist lateral forces in the plane of the wall through shear and bending.

Front 114

Shear wall materials-

Back 114

plywood on wood frame, concrete or reinforce masonry.

Front 115

Braced frames-

Back 115

truss system in which lateral forces are resisted through axial stresses (direct tension and compression) in the members. Diagonal members, placement.

Front 116

Braced Frames material-

Back 116

typically steel

Front 117

Moment-resisting frames-

Back 117

uses rigid connections to carry lateral loads primarily by flexure (bending). No diagonal members. Greater drifts than shear walls or brace frame.

Front 118

Moment-resisting frames material-

Back 118

concrete of steel.

Front 119

Which plan shapes of buildings are bad for earthquakes?

Back 119

T, U, L (Dont want thin shells, cable-supported structure, hillside location, tall buildings and high first story.)

Front 120

Ideal plan of building shapes for Earthquakes:?

Back 120

compact and symmetrical.

Front 121

Drift-

Back 121

a limiting factor is important in order to ensure that exterior facades dont break off or crack. Drift for EQ's are limited to 0.005 X building height.

Front 122

Dynamic loads-

Back 122

when a load is applied suddenly or changes rapidly. EX) elevators

Front 123

Impact load-

Back 123

suddenly applied loads. Fleeting equivalent to many times their statically applied weights. EX) snow shedding from a roof (high roof to a lower roof)

Front 124

Resonant Loads-

Back 124

a rhythmic application of a force to a structure with the same fundamental period as the structure itself.

Front 125

Fundamental period-

Back 125

time it takes the structure to complete one full oscillation. Effects increase steadily with time.

Front 126

Temperature-Induced loads-

Back 126

(based on expansion and contraction) modern buildings dont last as long as older buildings bc the expansion- contraction of steel is 2 times as much as older building materials.

Front 127

Settlement loads-

Back 127

when parts of the building sink into the ground. causes the most damage in buildings.

Front 128

Water loads-

Back 128

loads from water can occur in many situations, in water tanks, swimming pools and against retaining walls holding back ground water. The loads developed from water and other liquids is equal to the unit weight of the fluid in pounds per cubic foot multiplied by its depth.

Front 129

Hydrostatic Pressure-

Back 129

unit weight of liquid (62.4 pcf for water) X depth

Front 130

Cyclopean (big) Dry Masonry-

Back 130

Constructing stone walls with out any mortar (weak method) Characteristics: low resistance and stability. Cant carry a lot of load, tend to slide under lateral load. Current applications: Garden enclosures and retaining walls. (If they fall, jut build them back up)

Front 131

Stone Masonry-

Back 131

Binding of stone with mortar. Mixture of Portland Cement, Lime, sand, water and additives to improve workability.

Front 132

Characteristics of Stone Masonry-

Back 132

1. Greater reistance than dry masonry.
2. Strong in compression (factor of strength of stone and mortar), weak in tension (weak in joint, requires great mass)

Front 133

Applications of Stone Masonry-

Back 133

1. Monumental structures (cemetery, foundation walls)
2. Structure subject only to compression (arches and vaults, short columns.)
3. Fireplaces (For real fireplaces, stone doesn't burn)
4. Retaining walls

Front 134

What is the size of a standard brick?

Back 134

L: 7 -5/8
W: 3-5/8
H: 2-1/4

Front 135

Brick-

Back 135

Manufactured (factory made, standard, more practical.) Drying: small size and hollow so it facilitates the drying process.
Weak in tension, works pretty well in an arch.

Front 136

What are the two types of brick bonds?

Back 136

1. Flemish bond 8 inches
2. English bond 12 inches

Front 137

Types of Brick Applications-

Back 137

arches, garden structures, retaining walls

Front 138

Mortar-

Back 138

mixture of Portland Cement, lime, sand, water and additives to improve workability. Joint thickness: 1/4 In to 5/8 In. Should not be used in freezing conditions.

Front 139

**Types of Mortar Strength

Back 139

Type M- strongest, earthquakes
Type S- Structures below grade
Type N- Structures above grade
Type O- Non-bearing partitions (cannot be frozen)
Type K- Tuck Pointing, replacing old mortar.

Front 140

Adobe-

Back 140

Older and coming back, from N Africa
Erosion: weak in compression and tension and when it rains it washes some of the adobe away, cracks. resurface the building once a year. Stronger in compression than tension, but low values of tension and compression.

Front 141

Composition of Adobe-

Back 141

Mixture of clay and straw and water. mud construction, Take wood form and pack the adobe in it. THe wall has to be thicker because its weak.

Front 142

Adobe applications-

Back 142

Hot-aired climates. A lot of architects use it on their own houses. Arches, domes and vaults.
- American Southwest- use mud thats available. low rise construction, thick walls.
- Hassan Fathy- Egypt - low income people (housing),

Front 143

Mud Masonry-

Back 143

Stronger in compression then tension, same material as Adobe. Molded in situ- build the mud, take wood form and put mud in compression and repeat.

Front 144

Characteristics and applications of Mud Masonry-

Back 144

weak sructural material and subject to erosion. Applications: russian immigrant housing, cover them with wood siding, no erosion. wood acts as insulator, wooden stove heats house.

Front 145

Concrete-

Back 145

paste of cement and water which binds gravel and sand (aggregate).

Front 146

Characteristics of Concrete-

Back 146

*1. 28 day strength (doesnt reach full strength until 28 days later)
2. Strong in compression and weak in tension. (compression- 2,500 to 5,000 PSI up to 20,000 PSI Tension- 150 PSI)
3. shrinkage (occurs during the process of curing, tensile stresses develop during curing causing cracking.
4. Fire Resistance (incombustible, prolonged exposure to a fire will cause damage.)
5. Permeability

Front 147

Slump-

Back 147

workability of concrete is measured with a slump test. Typical slump is 2 in