Earthquake Earthquake BasicsBasics

Earthquake Earthquake BasicsBasicsSection 2Section 2

What causes earthquakes?What causes earthquakes?

How do earthquake forces enter How do earthquake forces enter buildings?buildings?

How does the building respond?How does the building respond?

What building elements resist What building elements resist forces?forces?

Strike-Slip FaultStrike-Slip FaultStrike-Slip FaultStrike-Slip Fault

Thrust FaultThrust FaultThrust FaultThrust Fault

EpicenterEpicenterEpicenterEpicenter

FaultFaultFaultFault

Point of fracture or Point of fracture or slippage, termed slippage, termed Focus or Hypocenter Focus or Hypocenter

Point of fracture or Point of fracture or slippage, termed slippage, termed Focus or Hypocenter Focus or Hypocenter

CaliforniCaliforniaa

IndexIndexMapMap

CaliforniCaliforniaa

IndexIndexMapMap

Distance to Fault SourceDistance to Fault Source

Surface GeologySurface Geology

WaterWater

SandSand

RockRock

FaultFault

Liquefaction FailureLiquefaction FailureLiquefaction FailureLiquefaction Failure

Inertia ForcesInertia ForcesInertia ForcesInertia Forces

ACCELERATIONACCELERATIONACCELERATIONACCELERATION

DECELERATIONDECELERATIONDECELERATIONDECELERATION

HD1HD1HD1HD1 HD2HD2HD2HD2ElevationElevationElevationElevation

HD3HD3HD3HD3 HD4HD4HD4HD4

Height / Weight Height / Weight RelationshipRelationship

Height / Weight Height / Weight RelationshipRelationship

0 1 011½

0 1 2 0 1 2 3

Building at RestBuilding at RestBuilding at RestBuilding at Rest Ground Accelerates to LeftGround Accelerates to LeftGround Accelerates to LeftGround Accelerates to Left

Ground Accelerates to RightGround Accelerates to RightGround Accelerates to RightGround Accelerates to Right Ground & Building at RestGround & Building at RestGround & Building at RestGround & Building at Rest

Period of VibrationPeriod of VibrationPeriod of VibrationPeriod of Vibration

Chimney Chimney Vibration Vibration FailureFailure

Chimney Chimney Vibration Vibration FailureFailure

Porch Vibration Porch Vibration FailureFailure

Porch Vibration Porch Vibration FailureFailure

Two Story Vibration Two Story Vibration FailureFailure

Two Story Vibration Two Story Vibration FailureFailure

Shear WallShear Wall

Cripple WallCripple Wall

FoundationFoundationFloorDiaphragm

FloorDiaphragm

Roof DiaphragmRoof Diaphragm

House Elements Resist House Elements Resist Horizontal ForcesHorizontal Forces

House Elements Resist House Elements Resist Horizontal ForcesHorizontal Forces

f1

f2

f3

fsum = f1 + f2 + f3fsum = f1 + f2 + f3

Cripple WallsCripple WallsCripple WallsCripple Walls

Crawl SpaceCrawl SpaceCripple WallCripple Wall

First FloorFirst Floor

Damage Resulting Damage Resulting from Base Shearfrom Base Shear

Damage Resulting Damage Resulting from Base Shearfrom Base Shear

Buildings Resist Buildings Resist Horizontal Earthquake Horizontal Earthquake

ForcesForces

Buildings Resist Buildings Resist Horizontal Earthquake Horizontal Earthquake

ForcesForces

Horizontal parts:Horizontal parts:Roof & floor structures Roof & floor structures diaphragmsdiaphragms

Vertical parts:Vertical parts:Span horizontal elements shear Span horizontal elements shear wallswalls

Complete Load PathComplete Load PathComplete Load PathComplete Load Path

No Shear Wall at No Shear Wall at GarageGarage

No Shear Wall at No Shear Wall at GarageGarage

Steel Moment FrameSteel Moment Frame

House Elements Resist House Elements Resist GravityGravity

House Elements Resist House Elements Resist GravityGravity

Roof JoistsRoof Joists

WallsWalls

Floor BeamsFloor Beams

FoundationsFoundations