Seismic Vulnerability of Buildings: Classification according to EMS-98

(1)

Research Collection

Educational Material

Seismic Vulnerability of Buildings: Classification according to EMS-98

Author(s):

Wenk, Thomas Publication Date:

2011-10-03 Permanent Link:

https://doi.org/10.3929/ethz-b-000439877

Rights / License:

In Copyright - Non-Commercial Use Permitted

This page was generated automatically upon download from the ETH Zurich Research Collection. For more information please consult the Terms of use.

(2)

Dr. Thomas Wenk

Course: Engineering Seismology

Fall Semester 2011 October 3, 2011

Seismic Vulnerability of Buildings:

Classification according to EMS-98

Earth Science Master

Thomas Wenk Engineering Seismology, ETH Zürich, Oct 3, 2011

EMS-98 Intensity Scale:

Vulnerability Classes

•

Differentiation of buildings into six Vulnerability Classes: VC A to VC F

•

The VC is typically determined based on a rapid visual inspection of the facades of traditional

buildings.

•

In modern „Skelettbauten“, the structural system has to be inspected. The facades are secondary elements.

•

It is easier to determine the VC of damaged than of undamaged buildings because the structural system of a building becomes more clearly visible with increasing

damage.

2 MACROSEISMIC INTENSITY SCALE

Classifications used in the European Macroseismic Scale (EMS) Differentiation of structures (buildings) into vulnerability classes

(Vulnerability Table)

The masonry types of structures are to be read as, e.g., simple stone masonry, whereas the reinforced concrete (RC) structure types are to be read as, e.g., RC frame or RC wall.

See section 2 of the Guidelines and Background Materials for more details, also with respect to the use of structures with earthquake resistant design.

[Grünthal et al. 1998]

(3)

EMS-98 Intensity Scale:

Damage Grades of Masonry Buildings

•

Illustration of Damage Grades: DG 1 to 5 of unreinforced masonry buildings.

•

Target of ERD is typically a damage smaller than DG 3 for the design

earthquake.

3

EMS-98 Intensity Scale: Determination of Intensity

•

The intensity is determined by a statistical analysis of the building damage of several neighbouring buildings and not by a single building.

•

^Examples:

-

Intensity VII:

many buildings of VC A suffer DG 3 and a few DG 4 many buildings of VC B suffer DG 2 and a few DG 3 a few buildings of VC C suffer DG 2

a few buildings of VC D suffer DG 1

-

Intensity VIII:

many buildings of VC A suffer DG 4 and a few DG 5 many buildings of VC B suffer DG 3 and a few DG 4 many buildings of VC C suffer DG 2 and a few DG 3 a few buildings of VC D suffer DG 2

•

Definition of quantities: few / many / most:

(4)

Earthquake Resistant Design

•

Buildings are primarily designed to carry gravity loads acting vertically.

•

Seismic forces act primarily in the horizontal direction.

•

Without ERD, buildings are only able to carry small horizontal forces.

5

Chile Earthquake MW = 8,8 27.2.2010

Photo: T. Wenk

Classification of Masonry Buildings

•

Rubble stone masonry: VC A

•

^{DG 5}

•

Ceyhan, Turkey 1998

Photo: T. Wenk

(5)

Classification of Masonry Buildings

•

Field stone masonry: VC A

•

Bad mortar quality

•

Timber floor

•

^{DG 4}

•

Aegion, Greece 1995

7

Photo: T. Wenk

Classification of Masonry Buildings

•

Field stone masonry: VC A

•

Bad mortar quality

•

Timber floor

•

^{DG 4}

•

Photo: T. Wenk

(6)

Classification of Masonry Buildings

•

Adobe masonry (earth bricks): VC A

•

^{DG 5}

•

Patras, Greece 2008

9

Photo: T. Wenk

Classification of Masonry Buildings

•

Simple stone masonry: VC B

•

Timber floors

•

^{DG 2}

•

Vaz GR, Switzerland 1991

Photo: T. Wenk

(7)

Classification of Masonry Buildings

•

Simple stone masonry: VC B

•

Timber floors

•

^{DG 2}

•

Vaz GR, Switzerland 1991

11

Photo: T. Wenk

Classification of Masonry Buildings

•

Unreinforced masonry with manufactured stone units (bricks): VC: C

•

Reinforced concrete floors

•

Regular layout

•

^{DG 3}

•

Photo: T. Wenk

(8)

Classification of Masonry Buildings

•

Unreinforced masonry with manufactured stone units (bricks):

VC: C

•

Reinforced concrete floors

•

Regular layout

•

^{DG 3}

•

13

Photo: T. Wenk

Classification of Masonry Buildings

•

Confined masonry, irregular layout in plan: VC C

•

Inverse sequence of construction:

masonry wall is built before reinforced concrete columns are poured.

•

Toothing between masonry wall and reinforced concrete columns

•

Reconstruction after the Wenchuan Earthquake, China, 2008

Photo: T. Wenk

(9)

Classification of Reinforced Concrete Buildings

•

RC frame with partial masonry infills

•

without ERD

•

serious structural deficiencies in the disposition of the reinforcement bars.

•

^{VC: A}

•

^{DG: 5}

•

Izmit, Turkey 1999

15

Photo: T. Wenk

Classification of Reinforced Concrete Buildings

•

RC frame with masonry infills without ERD

•

Serious structural deficiency:

Soft-story in the ground floor

•

^{VC: A}

•

^{DG: 5}

•

(10)

Classification of Reinforced Concrete Buildings

•

RC frame with masonry infills without ERD

•

Serious structural deficiency:

Soft-story in the ground floor

•

^{VC: A}

•

^{DG: 5}

•

17

Photo: T. Wenk

Classification of Reinforced Concrete Buildings

•

RC frame with masonry infills and moderate level of ERD

•

Serious structural deficiency:

Soft-story in the ground floor

•

^{VC: B}

•

^{DG: 5}

•

Kobe, Japan 1995

Photo: T. Wenk

(11)

Classification of Reinforced Concrete Buildings

19

•

RC frame with masonry infills and moderate level of ERD

•

Serious structural deficiency:

Soft-story in the ground floor

•

^{VC: B}

•

^{DG: 5}

•

Photo: T. Wenk

Classification of Reinforced Concrete Buildings

•

RC frame with RC walls and moderate level of ERD.

•

Serious structural deficiencies:

- Soft-story in the ground floor - large eccentricity of bracing system: torsion

•

^{VC: C}

•

^{DG: 5}

•

Photo: T. Wenk

(12)

Classification of Reinforced Concrete Buildings

•

RC walls with high level of ERD.

•

- Soft-story at set back level - large eccentricity of bracing system due to wall on back side:

torsion

•

VC: D or C?

•

^{DG: 4}

•

Concepcion, Chile 2010

21

Photo: T. Wenk

Classification of Reinforced Concrete Buildings

•

RC walls with high level of ERD.

•

- Soft-story at set back level - large eccentricity of bracing system due to wall on back side:

torsion

•

VC: D or C?

•

^{DG: 4}

•

Concepcion, Chile 2010

(13)

Classification of Steel Buildings

•

Steel structure: X-Bracing

•

Regular layout in plan and elevation respecting conceptual seismic design rules

•

Designed for high seismic demand

•

^{VC: F}

•

Taipei, Taiwan

23

Photo: T. Wenk

Literature

Dazio A., Wenk T. (2008): Erdbebensicherung von Bauwerken II, Folienkopien HS 2008, E-Collection, ETH Zürich: www.research-collection.ethz.ch/bitstream/handle/20.500.11850/151798/eth-962-01.pdf

Grünthal G., Musson R.M.W., Schwarz J., Stucchi M. (1998): European Macroseismic Scale 1998

(EMS-98). Cahiers du Centre Européen de Géodynamique et de Séismologie, Vol. 15, Conseil de l’Europe, Luxembourg.

Wenk T. (2011): Erdbebensicherung von Bauwerken I, Folienkopien FS 2011, E-Collection, ETH Zürich:

www.research-collection.ethz.ch/bitstream/handle/20.500.11850/152828/eth-3020-01.pdf