Vulnerability of buildings to earthquake ground shaking
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VULNERABILITY OF BUILDINGS TO EARTHQUAKE GROUND SHAKING. GENERALIZED VULNERABILITY ASSESSMENTS BASED ON CHANGES IN A BUILDING’S ELEVATION AND FLOOR PLAN. Walter Hays, Global Alliance for Disaster Reduction, University of North Carolina, USA. HAZARDS. EXPOSURE.

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VULNERABILITY OF BUILDINGS TO EARTHQUAKE GROUND SHAKING

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VULNERABILITY OF BUILDINGS TO EARTHQUAKE GROUND SHAKING

GENERALIZED VULNERABILITY ASSESSMENTS BASED ON CHANGES IN

A BUILDING’S ELEVATION AND FLOOR PLAN

Walter Hays, Global Alliance for Disaster Reduction, University of North Carolina, USA


HAZARDS

EXPOSURE

VULNERABILITY

LOCATION

ELEMENTS OF RISK

RISK


BUILDING DAMAGE: DEATH TOLL REACHED 230,,000


CAUSES OF DAMAGE

INADEQUATE RESISTANCE TO HORIZONTAL GROUND SHAKING

SOIL AMPLIFICATION

PERMANENT DISPLACEMENT (SURFACE FAULTING & GROUND FAILURE)

IRREGULARITIES IN ELEVATION AND PLAN

EARTHQUAKES

TSUNAMI WAVE RUNUP

CASE HISTORIES

LACK OF DETAILING AND POOR CONSTRUCTION MATERIALS

LACK OF ATTENTION TO NON-STRUCTURAL ELEMENTS


GOAL: REGULARITY IN BUILDING ELEVATIONS AND SIMPLICITY IN FLOOR PLANS

EFFECTIVE WHEN IMPLEMENTED IN ACCORDANCE WITH BUILDING REGULATIONS DURING THE DESIGN AND CONSTRUCTION PHASES ---

NOT AS EFFECTIVE WHEN ADDED BY RETROFIT OR BY STRENGTHENING


ANY COMMUNITY CAN ASSESS THE VULNERABILITY OF ITS BUILDINGS BY EXAMINING EACH BUILDING’S ELEVATION AND FLOOR PLAN

  • An Incremental Process

CLARIFY VULNERABILTIES

INDENTIFY OPTIONS

IMPLEMENT BEST SOLUTION

OPTIMIZE

INITATE ACTIONS

EVALUATE


SOURCE OF INFORMATION

  • The following graphic assessments of building vulnerability to earthquake ground shaking were developed by an insurance company and provided to other organizations for educational uses.


BUILDING ELEVATIONS

  • Horizontal and vertical changes in symmetry, mass, and stiffness—deviations from regularity--- will increase a building’s vulnerability to damage from ground shaking.


AN IMPORTANT NOTE

  • NOTE: Analysis of the effects of changes in the local site geology and the construction materials, key parameters in controlling a building’s performance, are NOT considered here.


ANALYSIS OF VULNERABILITY

BUILDING ELEVATION

LOCATIONS OF POTENTIAL FAILURE

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

None, if attention given to foundation and non-structural elements. Rocking may crack foundation and structure. X-Cracks around windows.

1-2

Box


DAMAGED HOUSE:CHINA


ASYMmETRY and lateral changes: CHINA


ANALYSIS OF VULNERABILITY

BUILDING ELEVATION

LOCATIONS OF POTENTIAL FAILURE

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

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

1

Pyramid


ANALYSIS OF VULNERABILITY

BUILDING ELEVATION

LOCATIONS OF POTENTIAL FAILURE

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

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

4 - 6

Inverted Pyramid


ANALYSIS OF VULNERABILITY

BUILDING ELEVATION

LOCATIONS OF POTENTIAL FAILURE

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

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

5 - 6

“L”- Shaped Building


ANALYSIS OF VULNERABILITY

BUILDING ELEVATION

LOCATIONS OF POTENTIAL FAILURE

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

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

3 - 5

Inverted “T”


ANALYSIS OF VULNERABILITY

BUILDING ELEVATION

LOCATIONS OF POTENTIAL FAILURE

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

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

2 - 3

Multiple Setbacks


ANALYSIS OF VULNERABILITY

BUILDING ELEVATION

LOCATIONS OF POTENTIAL FAILURE

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

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

4 - 5

Overhang


ANALYSIS OF VULNERABILITY

BUILDING ELEVATION

LOCATIONS OF POTENTIAL FAILURE

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

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

6 - 7

Partial “Soft” Story


ANALYSIS OF VULNERABILITY

BUILDING ELEVATION

LOCATIONS OF POTENTIAL FAILURE

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

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

8 - 10

“Soft” First Floor


THE TYPICAL SOFT-STOREY BUILDING IN TURKEY


ANALYSIS OF VULNERABILITY

BUILDING ELEVATION

LOCATIONS OF POTENTIAL FAILURE

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

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

9 - 10

Combination of “Soft” Story and Overhang


ANALYSIS OF VULNERABILITY

BUILDING ELEVATION

LOCATIONS OF POTENTIAL FAILURE

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

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

10

Building on Sloping Ground


SOFT STORY BUILDING ON SLOPING GROUND: CHINA TRIGGERED LANDSLIDES


ANALYSIS OF VULNERABILITY

BUILDING ELEVATION

LOCATIONS OF POTENTIAL FAILURE

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

Horizontal and vertical transition in stiffness and cause failure of individual members.

8 - 9

Theaters and Assembly Halls


ANALYSIS OF VULNERABILITY

BUILDING ELEVATION

LOCATIONS OF POTENTIAL FAILURE

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

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

9 - 10

Sports Stadiums


BUILDING FLOOR PLANS

  • CHANGING FLOOR PLANS FROM SIMPLE TO COMPLEX AND FROM SYMMETRICAL TO ASYMMETRICAL WILL INCREASE A BUILDING’S VULNERABILITY TO GROUND SHAKING.


ANALYSIS OF VULNERABILITY

FLOOR PLAN

POTENTIAL PROBLEMS

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

None, if symmetrical layout maintained.

1

Box


ANALYSIS OF VULNERABILITY

FLOOR PLAN

POTENTIAL PROBLEMS

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

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

2 - 4

Rectangle


ANALYSIS OF VULNERABILITY

FLOOR PLAN

POTENTIAL PROBLEMS

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

Asymmetry will cause torsion and enhance damage at corners.

2 - 4

Street Corner


ANALYSIS OF VULNERABILITY

FLOOR PLAN

POTENTIAL PROBLEMS

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

Asymmetry will enhance damage at corner regions.

5 - 10

“U” - Shape


ANALYSIS OF VULNERABILITY

FLOOR PLAN

POTENTIAL PROBLEMS

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

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

4

Courtyard in Corner


ANALYSIS OF VULNERABILITY

FLOOR PLAN

POTENTIAL PROBLEMS

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

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

8

“L” - Shape


torsion:CHINA


ANALYSIS OF VULNERABILITY

FLOOR PLAN

POTENTIAL PROBLEMS

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

Directional variation in stiffness will enhance damage at intersecting corner.

5 - 7

“H” - Shape


ANALYSIS OF VULNERABILITY

FLOOR PLAN

POTENTIAL PROBLEMS

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

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

8 - 10

Complex Floor Plan


ANALYSIS OF VULNERABILITY

FLOOR PLAN

POTENTIAL PROBLEMS

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

Asymmetry and irregularities will cause torsion and enhance damage along boundaries and at corners.

5- 9

Curved Plan


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