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1. 2 World seismic activity British Geological Survey 2.

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Presentation on theme: "1. 2 World seismic activity British Geological Survey 2."— Presentation transcript:

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2 2 World seismic activity British Geological Survey 2

3 3 According to the Economic Commission for Latin America and the Caribbean (ECLAC), between 1981 and 1996 93 hospitals and 538 health centers were damaged as a result of natural disasters. Losses amounted to US$3.1 billion. This could be compared to an extreme situation in which 20 countries in the region had each suffered the loss of 6 major hospitals and 25 health centers. Impact of natural disasters on hospitals (1981 - 1996 ) Impact of natural disasters on hospitals (1981 - 1996 )

4 4 The occupancy rate is constant, 24 hours a day, year-round. It is almost impossible to evacuate a hospital in the event of an emergency. The survival of some patients depends on the proper operation of the equipment and the continuity of basic services. In emergencies and disasters, medical facilities are essential and must continue to function after the event has taken place. Hospitals are highly dependent on public utilities (water, electricity, communications, etc.) which are often interrupted in the event of a disaster. Hospitals are especially vulnerable to natural disasters

5 5 As a result of the collapse of Juarez Hospital during the 1985 Mexico City earthquake, a total of 536 beds were lost, and 561 people lost their lives

6 6 Partial collapse of a hospital during the Kobe, Japan, earthquake in 1995 O.D. Cardona

7 7 Magnitude Scale The magnitude of an earthquake is determined by the energy it releases. Modified Mercalli Intensity Scale The intensity of an earthquake is estimated based on the damage to man-made structures and people’s reactions to the ground motion. Methods for measuring earthquakes

8 8 Stiffness of the soil Depth of the compressible layer Liquefaction potential Potential for landslides Parameters that affect the response of the soil

9 9 The shape, amplitude, and the duration of a seismic movement are affected, among other things, by its magnitude, the distance to the hypocenter, and the local site conditions 9

10 10 Differential settlements of the soil caused by an earthquake can render health care facilities incapable of delivering their services NOAA, National Geophysical Data Center

11 11 Soil liquefaction can compromise the stability of a structure Soil liquefaction can compromise the stability of a structure NOAA, National Geophysical Data Center

12 12 Seismic motions combined with slopes and water-saturated soil can produce landslides

13 13 Soil-structure interaction 13

14 14 Types of foundations used in buildings 14

15 15 Internal forces of the components 15

16 16 Damage caused by axial load on column

17 17 Damage caused by shearing force on ground-floor columns

18 18 Structural damage mechanisms 18

19 19 Not recommended structural damage mechanism: damage to columns, not beams

20 20 Damage to joints or columns can cause the partial or total collapse of the structure

21 21 The structure must be planned, designed and built in such a way that: Philosophy behind the seismic design of hospitals It can withstand moderate earthquakes without any damage. It can withstand severe earthquakes with minor and easily repaired nonstructural damage. It can withstand exceptionally severe earthquakes with structural damage that can be repaired, and without interrupting the provision of health services.

22 22 T. Guevara, 1999 Response to different components and contents of a building during an earthquake 22

23 23 Different structural systems 23

24 24 Floor plan Eccentricity Elevation Mass concentrations on stories Design features that may lead to behavioral problems

25 25 Irregularities in the floor plan 25

26 26 Irregular floor plan O. D. Cardona, 1998

27 27 Use of seismic joints for structural designs of buildings with complex floor plans 27

28 28 The appropriate use of seismic joints makes it possible to design buildings with complex floor plans. Seismic joints Architectural components must respect seismic joints

29 29 Asymmetry (false symmetry) due to the location of structural elements 29

30 30 When there is eccentricity in a building, damage is usually concentrated in the components at each extreme

31 31 Examples of structures with irregularities in elevation 31

32 32 Irregular elevations 32

33 33 Discontinuity in the elements and the flow of forces F. Sauter

34 34 The discontinuity of vertical components increases the vulnerability of structures to earthquakes Before After

35 35 Concentrations of mass in the upper stories of buildings increase the vulnerability of structures to an earthquake Concentrations of mass in the upper stories of buildings increase the vulnerability of structures to an earthquake

36 36 Abrupt changes in the stiffness or the mass between stories Soft stories Interaction between nonstructural elements and the structure Short columns Pounding of adjacent buildings Physical aspects that cause behavioral problems in structures

37 37 Soft stories T. Guevara

38 38 Soft story as a result of the discontinuity of walls on the ground floor O.D. Cardona

39 39 The interaction of structural and nonstructural elements can cause considerable damage

40 40 Damage caused by the interaction of structural and nonstructural elements

41 41 Interaction between structural and nonstructural elements 41

42 42 Interaction of masonry walls with reinforced concrete frame, causing failure due to short columns 42

43 43 Short columns can and should be prevented M. Cruz

44 44 Pounding between adjacent buildings compromises their stability

45 45 Pounding area between buildings and ways of preventing it M. Cruz 45

46 46 The correct distance between buildings prevents pounding and the collapse of the structures.

47 47 The seismic-resistant design process 47

48 48 Recommended seismic behavior objectives, Vision 2000 = Critical security, as in hospitals and fire stations  = Essential or hazardous facility or component, such as telephone switchboards and buildings with toxic materials stored inside  = Basic or conventional facility, such as offices or homes ATC (Report 33-03). Guidelines for Seismic Rehabilitation of Buildings. 75% Submittal, Third Draft, 3 Volumes. Redwood City, 1995. NEHRP Guidelines for Seismic Rehabilitation of Buildings (FEMA 273) Required behavior

49 49 Objective To evaluate the likelihood of a structure suffering damage due to an earthquake, and to characterize the possible damage Objective of vulnerability assessments Objective of vulnerability assessments Available methodologies Qualitative methods Quantitative methods

50 50 Qualitative methods They assess quickly and simply the structural safety conditions of the building. The structure is rated, among other characteristics, according to the following: The age of the building The state of conservation The characteristics of the materials used The number of stories The architectural plan Estimation of base shear strength Quantitative methods The goal is to determine the levels of resistance, flexibility and ductility demands of the structure by means of an analysis similar to that used in new buildings, incorporating nonstructural elements. Vulnerability assessments

51 51 The goal is to ensure that the health care facility will continue to function after an earthquake, by reinforcing existing components or incorporating additional structural components to improve the levels of strength, stiffness and ductility capacity. The type of retrofitting should not interfere with the operations of the hospital during or after its construction. Structural reinforcement

52 52 Possible structural retrofitting solutions 52

53 53 Reinforcement method: addition of (interior or exterior) walls

54 54 Reinforcement method: Buttressed components used in the Cardiology Hospital of the Mexican Social Security Institute, Mexico

55 55 Reinforcement method: Energy dissipation devices used in the headquarters of the Mexican Social Security Institute, Mexico

56 56 Reinforcement method: Perimeter frames used in the Hospital México of the Costa Rican Social Security Fund, Costa Rica M. Cruz

57 57 Reinforcement method: External diagonals or braces O.D. Cardona

58 58 Reinforcement of structural components through the use of lining

59 59 General information about the reinforcement of the hospitals of the Costa Rican Social Security Fund

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