EARTHQUAKE ENGINEERING TERMS

Question 1

it is the space between two adjacent floors

Answer 1

story

Question 2

are rigid horizontal planes used to transfer lateral forces to vertical resisting elements

Answer 2

diaphragms

Question 3

refers to a wall designed to resist lateral forces acting in its own plane, typically wind and seismic loads

Answer 3

shear wall

Question 4

stiffened walls that are capable of transferring lateral forces from floors and roofs to the foundation

Answer 4

shear wall

Question 5

refers to the point where the object “suffers” no torque by the effect of the gravitational force acted upon it

Answer 5

center of gravity

Question 6

refers to the center of resistance of a floor or diaphragm against lateral forces

Answer 6

center of rigidity

Question 7

it is the point through which the resultant of the resistance to the applied lateral force acts

Answer 7

center of rigidity

Question 8

refers to the point through which the resultant of the masses of a system acts

Answer 8

center of mass

Question 9

it is the point through which the applied lateral force acts

Answer 9

center of mass

Question 10

refers to the point through which the resultant of the restoring forces of a system acts

Answer 10

center of stiffness

Question 11

refers to the distance between the center of rigidity and the center of mass

Answer 11

eccentricity

Question 12

refers to the total design lateral force at the base of a structure

Answer 12

design seismic base shear

Question 13

refers to the lateral displacement of one level relative to the level above or below

Answer 13

story drift

Question 14

refers to the lateral displacement of the story relative to the base

Answer 14

story displacement

Question 15

refers to the shear stress that occurs when the structure’s center of mass does not coincide with its center of rigidity

Answer 15

torsional shear stress

Question 16

refers to the phenomenon that occurs when a building period coincides with the earthquake period

Answer 16

resonance

Question 17

refers to the time period of undamped free vibration of a structure

Answer 17

natural period

Question 18

refers to the rate at which natural vibration is absorbed

Answer 18

damping

Question 19

the effect of internal friction, imperfect elasticity of material, slipping, sliding, etc. in reducing the amplitude of vibration

Answer 19

damping

Question 20

refers to the geographical point on the surface of earth vertically above the focus of the earthquake

Answer 20

epicenter

Question 21

refers to the origin/source of the elastic waves inside the earth which cause shaking of ground due to earthquake

Answer 21

focus

Question 22

refers to the capacity to undergo large inelastic deformations without significant loss of strength or stiffness

Answer 22

ductility

Question 23

refers to the state in saturated cohesionless soil wherein the effective shear strength is reduced to negligible value

Answer 23

liquefaction

Question 24

condition when soil tends to behave like a fluid mass

Answer 24

liquefaction

Question 25

five (5) factors that affect earthquake loads

Answer 25

* magnitude * proximity of structure from fault * type of system/structure * occupancy * soil properties

Question 26

refers to the measure of the strength of shaking during the earthquake

Answer 26

intensity

Question 27

it is sometimes presented in terms of observed damage

Answer 27

intensity

Question 28

refers to the measure of total energy released in an earthquake

Answer 28

magnitude

Question 29

this measure is often given by the Richter scale

Answer 29

magnitude

Question 30

refers to the instrument used to record the motion of the ground during an earthquake

Answer 30

seismograph

Question 31

the location where an earthquake is initiated

Answer 31

hypocenter

Question 32

the location of the hypocenter is defined by the _____, _____, and _____

Answer 32

latitude, longitude, and depth below the surface

Question 33

the point on the surface of the earth directly over the hypocenter

Answer 33

epicenter

Question 34

five (5) vertical structural irregularities

Answer 34

* stiffness irregularity (soft storey) * weight (mass) irregularity * vertical geometric irregularity * in-plane discontinuity in vertical lateral force-resisting element irregularity * discontinuity in capacity irregularity (weak storey)

Question 35

# vertical structural irregularity: refers to the condition wherein the lateral stiffness is less than 70% of that in the storey above or less than 80% of the average stiffness of the three stories above

Answer 35

stiffness irregularity (soft storey)

Question 36

# vertical structural irregularity: refers to the condition wherein the effective mass of any storey is more than 150% of the effective mass of an adjacent storey; a roof which is lighter than floor below need not be considered

Answer 36

weight (mass) irregularity

Question 37

# vertical structural irregularity: refers to the condition wherein the horizontal dimension of the lateral force-resisting system in any storey is more than 130% of that in an adjacent storey; one storey penthouse need not to be considered

Answer 37

vertical geometric irregularity

Question 38

# vertical structural irregularity: refers to the condition wherein an in-plane offset of the lateral load-resisting elements greater than the length of those elements

Answer 38

in-plane discontinuity in vertical lateral force-resisting element irregularity

Question 39

# vertical structural irregularity: refers to the condition wherein the storey strength is less than 80% of that in the storey above; the storey strength is the total strength of all seismic-resisting elements shearing the storey shear for the direction under consideration

Answer 39

discontinuity in capacity irregularity (weak storey)

Question 40

five (5) horizontal structural irregularities

Answer 40

* torsional irregularity * re-entrant corner irregularity * diaphragm discontinuity irregularity * out-of-plane offsets irregularity * non-parallel systems irregularity

Question 41

# horizontal structural irregularity: this irregularity is being considered when diaphragms are not flexible

Answer 41

torsional irregularity

Question 42

# horizontal structural irregularity: this irregularity exists when the maximum story drift, computed including accidental torsion, at one end of the structure transverse to an axis is more than 1.2 times the average of the story drifts of the two ends of the structure

Answer 42

torsional irregularity

Question 43

# horizontal structural irregularity: refers to the condition wherein parts of a structure project beyond a reentrant corner a distance greater than 15% of the plan dimensions in the given direction

Answer 43

re-entrant corner irregularity

Question 44

# horizontal structural irregularity: refers to the condition wherein diaphragms with abrupt discontinuities or variations in stiffness, including those having cutout or open areas greater than 50% of the gross enclosed area of the diaphragm, or changes in effective diaphragm stiffness of more than 50% from one-story to the next

Answer 44

diaphragm discontinuity irregularity

Question 45

# horizontal structural irregularity: refers to the condition wherein there are discontinuities in a lateral force path, such as out-of-plane offsets of the vertical elements

Answer 45

out-of-plane offsets irregularity

Question 46

# horizontal structural irregularity: refers to the condition wherein the vertical lateral-load-resisting elements are not parallel to or symmetric about the major orthogonal axes of the lateral force-resisting systems

Answer 46

non-parallel systems irregularity