Buildings at Risk - Seismic

Question 1

Accelerogram

Answer 1

The record from an accelerograph showing acceleration as a function of time.

Question 2

Accelerograph

Answer 2

A strong motion earthquake instrument recording accelerations

Question 3

Acceleration

Answer 3

rate of change of velocity with time

Question 4

Aftershock

Answer 4

an earthquake, usually a member of an aftershock series often within the span of several months following the occurrence of a large earthquake (main shock). The magnitude of an aftershock is usually smaller than the main shock

Question 5

Amplification

Answer 5

a relative increase in ground motion between one type of soil and another, or an increase in building response as result of resonance

Question 6

Base Isolation

Answer 6

A method whereby a building superstructure is detected from its foundation in order to change the characteristics of earthquake forces transmitted to the building

Question 7

Base Shear

Answer 7

Calculated total shear force acting at the base of a structure, used in codes as static representation of later earthquake forces. Also referred to as “equivalent lateral force”

Question 8

Brittle Failure

Answer 8

Failure in a material which generally has a very limited plastic range; material subject to sudden failure without warning.

Question 9

Damping

Answer 9

A rate at which natural vibration decays as a result of absorption of energy

Question 10

Deflection

Answer 10

the state of being turned aside from a straight line, generally used in the horizontal sense

Question 11

Amplitude

Answer 11

Maximum deviation from mean of the center line of a wave.

Question 12

Diaphragm

Answer 12

a horizontal or nearly horizontal structural element designed to transmit lateral forces to the vertical elements of the seismic resisting system

Question 13

Drift

Answer 13

Vertical deflection of a building or structure caused by lateral forces

Question 14

Ductility

Answer 14

Property of some materials, such as steel, to distort when subjected to forces while still retaining considerable strength

Question 15

Dynamic

Answer 15

Having to do with bodies in motion

Question 16

Elastic

Answer 16

The ability of a material to return to its original form and condition after displacing force is removed.

Question 17

Energy Absorption

Answer 17

Energy is absorbed as a structure distorts elastically.

Question 18

Energy Dissipation

Answer 18

Reduction in intensity of earthquake shock waves with time and distance, or by transmission through discontinuous materials with different absorption capabilities

Question 19

Epicenter

Answer 19

A point on the earths surface which is directly above the focus of an earthquake

Question 20

Exceedance Probability

Answer 20

the probability that a specified level of ground motion or specified social or economic consequences of earthquakes will be exceeded at a site or in a region during a specified exposure time.

Question 21

Exposure

Answer 21

The potential economic loss to all or certain subsets of the built environment as a result of one or more earthquakes in an area. This term usually refers to the insured value of structures carried by one or more insurers

Question 22

Failure Mode

Answer 22

The manner in which a structure fails (column buckling, overturning, etc. )

Question 23

Design Earthquake

Answer 23

In the NEHRP Provisions the earthquake that produces ground motions at the site under consideration that have a 90% probability of not being exceeded in 50 years (or a 10% probability of being exceeded). This is equivalent to a mean Return Period of 475 years, or an annual risk or 0.002 events a year.

Question 24

Fault

Answer 24

A fracture in the earth’s crust accompanied by displacement of one side of the fracture with respect to the other and in a direction parallel to the fracture

Question 25

Normal Fault

Answer 25

A fault under tension where the overlaying block moves down the dip or slop of the fault plane

Question 26

Strike-Slip Fault

Answer 26

Or lateral slip, A fault whose relative displacement is purely horizontal

Question 27

Thrust (Reverse) Fault

Answer 27

A fault under compression where the overlaying block moves up the dip of the fault plane

Question 28

Oblique-Slip Fault

Answer 28

A combination of normal and slip or thrust and slip faults whose movement is diagonal along the dip of the fault plane

Question 29

Describe the 6 Seismic design Categories

Answer 29

Category A: corresponds to building in areas where expected ground shaking is minor Category B: corresponds to buildings of occupancy categories I, II, III in areas where moderately destructive ground shaking is expected Category C: corresponds to buildings of the occupancy category IV, in areas where moderately destruction ground shaking might take place , and to I, II, III in areas where severe destructive ground shaking is expected Category D: corresponds to buildings and structures in areas expected to experience severe and destructive ground shaking but not located close to major active fault lines. Category E: corresponds to buildings of occupancy categories I, II, III in areas located near major active fault lines Category F: corresponds to buildings of occupancy category IV in areas located near major active fault lines

Question 30

Focus

Answer 30

The location of the fault break where an earthquake originates

Question 31

Force

Answer 31

Agency or influence that tries to deform an object or overcome its resistance to motion

Question 32

Braced Frame

Answer 32

One which is dependent upon diagonal braces for stability and capacity to resist lateral forces. In concentric braced frames, diagonal braces are arranged concentric to columns/beam joints; in eccentric braced frames, they are eccentric.

Question 33

Moment Frame

Answer 33

A space frame in which members and joints are capable of resisting lateral forces by bending as well as along the axis of the members. varying levels of resistance are provided by Ordinary, Intermediate, and Special Moment frames as defined in the NEHRP provisions with special frames providing the most resistance.

Question 34

Frame, Space

Answer 34

A structural system composed of interconnected members, other than bearing walls, that is capable of supporting vertical loads and that may also provide resistance to seismic forces.

Question 35

Frequency

Answer 35

Referring to vibrations, the number of wave peaks which pass through a point in a unit of time, usually measured in cycles per second.

Question 36

Ground Failure

Answer 36

Physical changes to the ground surface produced by an earthquake, such as lateral spreading, landslides, and liquefaction.

Question 37

"G"

Answer 37

The acceleration due to gravity, or 32' per second

Question 38

Inelastic

Answer 38

The inability of a material to return to its original form and condition after a displacing force is removed, permanent distortion

Question 39

Intensity

Answer 39

A subjective measure of the force of an earthquake at a particular place as measured by its effects on person, structures, and earth materials. Intensity is a measure of energy. The principle scaled used in the United States today is the Modified Mercalli, 1956 version.

Question 40

Irregular

Answer 40

Deviation of a building configuration from a simple symmetrical shape.

Question 41

Lateral Force Coefficients

Answer 41

Factors applied to the weight of a structure or its parts to determine lateral forces for seismic design

Question 42

Liquefaction

Answer 42

Transformation of a granular material (soil) from a solid state into a liquefied state as a consequence of increased pore-water pressure induced by vibration

Question 43

Microzone (microzonation)

Answer 43

seismic zoing, generally by use of maps, for land areas smaller than regions shown in typical seismic code maps, but larger than individual building sites

Question 44

Irregular

Answer 44

Deviation of a building configuration from a simple symmetrical shape.

Question 45

Nonstructural Components

Answer 45

Those building components which are not intended primarily for structural support and bracing of the building

Question 46

Liquefaction

Answer 46

Transformation of a granular material (soil) from a solid state into a liquefied state as a consequence of increased pore-water pressure induced by vibration

Question 47

Microzone (microzonation)

Answer 47

seismic zoing, generally by use of maps, for land areas smaller than regions shown in typical seismic code maps, but larger than individual building sites

Question 48

Modal Analysis

Answer 48

determination of seismic design forces based upon the theoretical response of a structure to excitation in its several modes of vibration

Question 49

Nonstructural Components

Answer 49

Those building components which are not intended primarily for structural support and bracing of the building

Question 50

Out of Phase

Answer 50

The state where a structure in motion is not at the same frequency as the ground motion or an adjoining structure, or where equipment in a building vibrates at a different frequency from the structure.

Question 51

Period

Answer 51

The elapsed time (generally in seconds) of a single cycle of a vibratory motion or oscillation: the inverse of frequency

Question 52

Resonance

Answer 52

The amplification of a vibratory motion occurring when the period of an impulse or periodic stimulus coincides with the period of the oscillating body.

Question 53

Seismic zone

Answer 53

Generally, areas defined on the map within which seismic design requirements are constant. In the NEHRP provisions, seismic zones are defined by both contour line and county boundaries

Question 54

Shear

Answer 54

A force which acts by attempting to cause the fibers or planes of an object to slide over one another

Question 55

Soil structure interaction

Answer 55

The effects of the properties of both soil and structure upon response of the structure

Question 56

Spectrum

Answer 56

A plot for a specific site indicating maximum earthquake response with respect to natural period or frequency of the structure or element. The response can be measured as acceleration, velocity, displacement or other properties.

Question 57

Speed

Answer 57

Rate of change of distance traveled with time, irrespective of directions

Question 58

Stiffness

Answer 58

Resistance to deflection or Drift of a structural component or system

Question 59

Story drift

Answer 59

Vertical deflection of a single story of a building caused by lateral forces.

Question 60

Strain

Answer 60

Deformation of a material per unit of the original dimension

Question 61

Strength

Answer 61

The capability of a material or structural member to resist or withstand applied forces

Question 62

Stress

Answer 62

Applied load per unit area, or internal resistance within a material that opposes a forces attempt to deform.

Question 63

System

Answer 63

An assembly of components or elements designed to perform a specific function, such as structural system

Question 64

Torque

Answer 64

The action of forced the tends to produce torsion. The product of a force and lever arm, as in the action of using a wrench to tighten a nut.

Question 65

Tsunami

Answer 65

A sea wave produced by large area displacement of the ocean bottom, the result of earthquakes or volcanic eruptions

Question 66

Velocity

Answer 66

Rate of change of distance traveled with time in a given direction. In earthquakes, it usually refers to seismic waves and is expressed and inches or centimeters per second.

Question 67

Rigidity

Answer 67

Relative stiffness of a structure or element. And numerical terms, equal to the reciprocal of displacement caused by unit force.

Question 68

Seismic

Answer 68

Of, subject to, or caused by an earthquake or in earth vibration.

Question 69

Seismic event

Answer 69

That abrupt release of energy in the earths lithosphere causing an earth vibration: an earthquake.

Question 70

Seismic hazard

Answer 70

Any physical phenomenon such as ground shaking or ground failure associated with an earthquake that may produce adverse effects on the built environment and human activities: also, the probability of earthquakes of defined magnitude or intensity affecting a given location.

Question 71

Seismic performance category

Answer 71

A classification assigned and the NEHRP provisions to the building based on it's seismic hazard exposure group and it's seismic hazard.

Question 72

Seismic resisting system

Answer 72

The part of the structural system that is designed to provide required resistance to prescribed seismic forces

Question 73

Seismic risk

Answer 73

The probability that social or economic consequences of an earthquake will equal or exceed specified values at a site during a specified exposure time: in general, seismic risk is vulnerability multiplied by the seismic hazard.

Question 74

Richter magnitude ( or scale )

Answer 74

A measure of earthquake size which is determined by taking the common logarithm (base 10) of the largest ground motion recorded during the arrival of a P-wave or seismic surface wave and applying a standard correction for distance to the epicenter. The scale is named after its creator, American size otologist Charles R Richter.

Question 75

Return period

Answer 75

The time period In years in which the probability is 63% that an earthquake of a certain magnitude will recur.

Question 76

Wall, bearing

Answer 76

A wall providing support for vertical loads: it may be interior or exterior

Question 77

Wall, sheer

Answer 77

A wall, bearing or non-bearing, designed to resist seismic forces acting in the plane of the wall

Question 78

P – wave

Answer 78

The primary, or fastest waves traveling away from a fault rupture through the Earth's crust, and consisting of a series of compressions and dilations of the ground material.

Question 79

Rayleigh wave

Answer 79

Forward and vertical vibration of seismic surface waves.

Question 80

S – wave

Answer 80

Shear, or secondary wave, produced essentially by the shearing or tearing motions of earthquakes at right angles to the direction of wave propagation.