lessons learned from past notable disasters mexico part 3b: earthquake vulnerability of buildings...

LESSONS LEARNED FROM PAST NOTABLE DISASTERS

MEXICOPART 3B: EARTHQUAKE

VULNERABILITY OF BUILDINGS

Walter Hays, Global Alliance for Disaster Reduction, Vienna,

Virginia, USA

MEXICO

MEXICO IS ON THE PACIFIC RIM WHERE A LARGE FRACTION OF THE GLOBAL SEISMICITY OCCURS

NATURAL HAZARDS THAT HAVE CAUSED NATURAL HAZARDS THAT HAVE CAUSED DISASTERS IN MEXICODISASTERS IN MEXICO

FLOODS

SEVERE WINDSTORMS

EARTHQUAKES

VOLCANIC ERUPTIONS

ENVIRONMENTAL CHANGE

GLOBAL CLIMATE CHANGE

HIGH BENEFIT/COST FROM BECOMING DISASTER RESILIENT

GOAL: PROTECT PEOPLE GOAL: PROTECT PEOPLE AND COMMUNITIESAND COMMUNITIES

MEXICO EXPERIENCED A M8.1 SUBDUCTION ZONE QUAKE IN 1985

BUILDING VULNERABILITY WAS (AND STILL IS) A

MAJOR FACTOR IN MEXICO’S LOSSES IN 1985

Mexico’s building stock, like the building stock of all countries,

has vulnerabilities as a result of

irregularities in elevation and plan, construction materials,

and the underlying soil

HAZARDSHAZARDSHAZARDSHAZARDS

ELEMENTS OF EARTHQUAKE ELEMENTS OF EARTHQUAKE RISK RISK

EXPOSUREEXPOSUREEXPOSUREEXPOSURE

VULNERABILITYVULNERABILITYVULNERABILITYVULNERABILITY LOCATIONLOCATIONLOCATIONLOCATION

RISKRISKRISKRISK

EARTHQUAKEHAZARD MODEL

SEISMICITYSEISMICITY TECTONICSETTING &

FAULTS

TECTONICSETTING &

FAULTS

TECTONIC DEFORMATION

EARTHQUAKE

TSUNAMI

GROUND

SHAKING

FAULT RUPTURE

FOUNDATION FAILURE

SITE AMPLIFICATION

LIQUEFACTION

LANDSLIDES

AFTERSHOCKS

SEICHE

DAMAGE/LOSSDAMAGE/LOSS

DAMAGE/ LOSSDAMAGE/ LOSS

DAMAGE/LOSSDAMAGE/LOSS

EXPOSUREMODEL

LOCATION OF STRUCTURE

IMPORTANCE AND VALUE OF

STRUCTURE AND CONTENTS

IMPORTANCE AND VALUE OF

STRUCTURE AND CONTENTS

VULNERABILITYMODEL

QUALITY OF DESIGN AND

CONSTRUCTION

QUALITY OF DESIGN AND

CONSTRUCTION

ADEQUACY OF LATERAL-FORCE

RESISTING SYSTEM

ADEQUACY OF LATERAL-FORCE

RESISTING SYSTEM

UNREINFO

RCED MASO

NRY, BRIC

K OR S

REINFORCED C

ONCRETE WIT

H UNREIN

FORCED WALLS

INTENSITYINTENSITY

REINFORCED CONCRETE WITH REINFORCEDWALLS

STEEL FRAME

ALL METAL & WOOD FRAME

VV VIVI VIIVII VIIIVIII IXIX

CONSTRUCTION MATERIALS HAVE DIFFERENT VULNERABILITIES TO GROUND

SHAKING

CONSTRUCTION MATERIALS HAVE DIFFERENT VULNERABILITIES TO GROUND

SHAKING

INADEQUATE RESISTANCE TO HORIZONTAL GROUND SHAKING

EARTHQUAKESEARTHQUAKES

SOIL AMPLIFICATION

PERMANENT DISPLACEMENT (SURFACE FAULTING & GROUND

FAILURE)

IRREGULARITIES IN ELEVATION AND PLAN

FIRE FOLLOWING RUPTURE OF UTILITIES

LACK OF DETAILING AND CONSTRUCTION MATERIALS

INATTENTION TO NON-STRUCTURAL ELEMENTS

CAUSES OF DAMAGE

“DISASTER LABORATORIES”

MEXICO CITY HAS SOFT SOILS THAT AMPLIFY GROUND SHAKING

MEXICO CITY HAS VULNERABLE SHORT BUILDINGS

MEXICO CITY HAS VULNERABLE TALL BUILDINGS

POLICY POLICY ADOPTIONADOPTION

RISK ASSESSMENT

• VULNERABILITYVULNERABILITY

• EXPOSUREEXPOSURE

• EVENTEVENT

POLICY ASSESSMENT

• COSTCOST

• BENEFITBENEFIT

•CONSEQUENCESCONSEQUENCES

REDUCING BUILDING VULNERABILITY REDUCING BUILDING VULNERABILITY REDUCES THE COMMUNITY’S RISKREDUCES THE COMMUNITY’S RISK

AN EARTH-AN EARTH-QUAKEQUAKE

AN EARTH-AN EARTH-QUAKEQUAKE EXPECTED EXPECTED

LOSSLOSS

EXPECTED EXPECTED LOSSLOSS

VULNERABILITY REDUCTION IS A CLASSIC EXAMPLE OF

STRATEGIC COLLABORATION

ACKNOWLEDGMENT: The vulnerability analyses that follow are based on global experience of a major reinsurance company that was shared for the benefit of all countries having buildings at

risk in future earthquakes.

ANALYSIS OF VULNERABILITY DUE TO

IRREGULARITIES IN BUILDING ELEVATIONS

RELATIVE VULERABILITY

[1 (Best) to 10 (Worst)]

1-21-2

ANALYSIS OF VULNERABILITY

LOCATIONS OF POTENTIAL FAILURE

None, if attention given to foundation and non structural elements. Rocking may crack foundation and structure.

BUILDING ELEVATION

BoxBox

None, if attention given to foundation and non structural elements. Rocking may crack foundation.

BUILDING ELEVATION

PyramidPyramid

2 - 32 - 3

Vertical transition in mass, stiffness, and damping may cause failure at foundation and transition points at each floor.

BUILDING ELEVATION

Multiple SetbacksMultiple Setbacks

4 - 64 - 6

Top heavy, asymmetrical structure may fail at foundation due to rocking and overturning.

BUILDING ELEVATION

Inverted PyramidInverted Pyramid

5 - 65 - 6

Asymmetry and horizontal transition in mass, stiffness and damping may cause failure where lower and upper structures join.

BUILDING ELEVATION

““L”- Shaped L”- Shaped BuildingBuilding

3 - 53 - 5

Vertical transition and asymmetry may cause failure where lower part is attached to tower.

BUILDING ELEVATION

Inverted “T”Inverted “T”

4 - 54 - 5

Top heavy asymmetrical structure may fail at transition point and foundation due to rocking and overturning.

BUILDING ELEVATION

OverhangOverhang

SOFT-STOREY BUILDINGS ARE THE MOST VULNERABLE

6 - 76 - 7

Horizontal and vertical transitions in mass and stiffness may cause failure on soft side of first floor; rocking and overturning.

BUILDING ELEVATION

Partial “Soft” StoryPartial “Soft” Story

8 - 108 - 10

Vertical transitions in mass and stiffness may cause failure on transition points between first and second floors.

BUILDING ELEVATION

““Soft” First FloorSoft” First Floor

9 - 109 - 10

Horizontal and vertical transitions in mass and stiffness may cause failure at transition points and possible overturning.

BUILDING ELEVATION

Combination of Combination of “Soft” Story and “Soft” Story and

OverhangOverhang

9 - 109 - 10

Horizontal and vertical transition in mass and stiffness may cause failure columns.

BUILDING ELEVATION

Sports StadiumsSports Stadiums

Horizontal transition in stiffness of soft story columns may cause failure of columns at foundation and/or contact points with structure.

BUILDING ELEVATION

Building on Building on Sloping GroundSloping Ground

IRREGULARITIES IN PLAN

RELATIVE VULERABILITY [1 (Best) to 10 (Worst)]

POTENTIAL PROBLEMS

None, if symmetrical layout maintained.

FLOOR PLANFLOOR PLAN

BoxBox

2 - 42 - 4

POTENTIAL PROBLEMS

Differences in length and width will cause differences in strength, differential movement, and possible overturning.

RectangleRectangle

2 - 42 - 4

POTENTIAL PROBLEMS

Asymmetry will cause torsion and enhance damage at corners.

Street CornerStreet Corner

POTENTIAL PROBLEMS

Open space in center reduces resistance and enhance damage at corner regions.

Courtyard in CornerCourtyard in Corner

4 - 54 - 5

POTENTIAL PROBLEMS

Asymmetry will cause torsion and enhance damage along curved boundary.

TheatersTheaters

5 - 105 - 10

POTENTIAL PROBLEMS

Asymmetry will enhance damage at corner regions.

““U” - ShapeU” - Shape

5 - 75 - 7

POTENTIAL PROBLEMS

Directional variation in stiffness will enhance damage at intersecting corner.

““H” - ShapeH” - Shape

POTENTIAL PROBLEMS

Asymmetry will cause torsion and enhance damage at intersection and corners.

““L” - ShapeL” - Shape

8 - 108 - 10

POTENTIAL PROBLEMS

Asymmetry and directional variation in stiffness will enhance torsion and damage at intersecting.

Complex Floor PlanComplex Floor Plan

IRREGULARITIES IN INTERNAL PROPERTIES

POTENTIAL PROBLEMS

Asymmetry and discontinuities in strength will cause torsion and concentrate stress around the opening.

INTERNAL PROPERTIES

Opening in Shear WallOpening in Shear Wall

POTENTIAL PROBLEMS

Asymmetry and variable stiffness will cause torsion and cracking/failure at staircase and elevator well.

INTERNAL PROPERTIES

Opening in Shear WallOpening in Shear Wall

POTENTIAL PROBLEMS

Variable stiffness will enhance cracking and failure on weaker side of structure.

INTERNAL PROPERTIES

Shear Wall or Retaining Shear Wall or Retaining Wall on only one sideWall on only one side

POTENTIAL PROBLEMS

Asymmetry and irregularities will cause torsion and enhance failure at all points of irregularity.

INTERNAL PROPERTIES

Different or Irregular Different or Irregular Spans; short columnsSpans; short columns

POTENTIAL PROBLEMS

Vertical transitions in seismic resistance will enhance failure at the “short columns”.

INTERNAL PROPERTIES

Window Bands Interrupting In-Window Bands Interrupting In-Fill WallsFill Walls

POTENTIAL PROBLEMS

Vertical transitions in stiffness will enhance failure at the transition points.

INTERNAL PROPERTIES

Three Story FrameThree Story Frame

POTENTIAL PROBLEMS

Vertical transitions in mass will enhance cantilever action, overturning moment, and failure at transition points.

INTERNAL PROPERTIES

Offset ColumnsOffset Columns

POTENTIAL PROBLEMS

Horizontal transition in depth of foundation will cause rocking and failure at edges.

INTERNAL PROPERTIES

Irregular FoundationIrregular Foundation

POTENTIAL PROBLEMS

Discontinuities in mass, stiffness, and damping will be enhanced at all transition points.

INTERNAL PROPERTIES

Industrial or Commercial FacilityIndustrial or Commercial Facility

POTENTIAL PROBLEMS

Top-heavy structures are vulnerable to distant earthquakes and resonance of thick soft soils because of vertical transition in mass.. Rocking, overturning, and foundation failure are enhanced.

INTERNAL PROPERTIES

Water TowerWater Tower

DUPONT

EMERGING TECHNOLOGIES FOR REDUCING

VULNERABILITIES IN PLAN AND ELEVATION

EMERGING TECHNOLOGIES FOR REDUCING

VULNERABILITIES IN PLAN AND ELEVATION

EMERGING TECHNOLOGIES EMERGING TECHNOLOGIES

• AUTOMATED CONSTRUCTION EQUIPMEMT

• PREFABRICATION AND MODULARIZATION

• ADVANCED MATERIALS (E.G., COMPOSITES)

• COMPUTER AIDED DESIGN

• PERFORMANCE BASED CODES AND STANDARDS

• ACTIVE AND PASSIVE ENERGY DISSIPATION DEVICES (E.G., BASE ISOLATION)

• REAL-TIME MONITORING AND WARNING SYSTEMS

• COMPUTER AIDED DESIGN

• PERFORMANCE BASED CODES AND STANDARDS

• ACTIVE AND PASSIVE ENERGY DISSIPATION DEVICES (E.G., BASE ISOLATION)

• REAL-TIME MONITORING AND WARNING SYSTEMS

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