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CT.Lakshmanan Assistant Professor (Selection Grade) School of Architecture & Interior Design SRM University Elementary Seismology Prepared by CT.Lakshmanan

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Introduction to Disaster management, causes of earthquake, earthquake design philosophy and earthquake resistant building techniques

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  • 1. CT.Lakshmanan Assistant Professor (Selection Grade) School of Architecture & Interior Design SRM University Elementary Seismology Prepared by CT.Lakshmanan

2. The Vulnerability Profile - India

  • 59%of land mass prone toearthquakes
  • 40 million hectares ( 8% ) of landmass prone tofloods
  • 8000 Km long coastlinewith twocyclone seasons
  • Hilly regionsvulnerable to avalanches/ landslides /Hailstorms/cloudburst
  • 68%of the total area susceptible todrought
  • Different types of manmade Hazards
  • Tsunami threat
  • 1 million houses damaged annually + human, economic, social and other losses

Prepared by CT.Lakshmanan 3. Prepared by CT.Lakshmanan 4. Hazard, vulnerability & disaster Disaster=F(Hazard, Vulnerability) Prepared by CT.Lakshmanan 5. Ingredients of Risk

  • Capacity-resources, means and strengths which exist in households and communities and which enable them to cope with, withstand, prepare for, prevent, mitigate or quickly recover from a disaster
  • H x V - C = R
  • Hazard x vulnerability capacity = risk
    • H - potential threat to humans and their welfare
    • V - exposure and susceptibility to loss of life or dignity
    • C - available and potential resources
    • R - probability of disaster occurrence

Prepared by CT.Lakshmanan 6. Disaster Prevention, Mitigation & preparedness

  • Prevention requires theelimination of riskwhile mitigation is thereduction of risk ..
  • Disaster Preparedness :Forecastand take precautionarymeasures in advanceof an imminent threat.

Prepared by CT.Lakshmanan 7. Prepared by CT.Lakshmanan 8. Seismology

  • The term Seismology is derived from Greek word Seismo, which meansearthquakeand logos meansscience ; hence theSeismology is Science of Earthquakes
  • Seismology can be defined in two ways:
  • 1. The science of earthquakes and the physics of the earths interior
  • 2. The science of elastic wave (seismic waves)

Prepared by CT.Lakshmanan 9. CONTINENTAL DRIFT Prepared by CT.Lakshmanan 10. Prepared by CT.Lakshmanan 11. Source: from internet Prepared by CT.Lakshmanan 12. Fault

  • A fault is nothing but a crack or weak zone inside the Earth. When two blocks of rock or two plates rub against each other along a fault, they dont just slide smoothly.
  • As the tectonic forces continue to prevail, the plate margins exhibit deformation as seen in terms of bending, compression, tension and friction. Therocks eventually break giving rise to an earthquake , because of building of stresses beyond the limiting elastic strength of the rock.

Prepared by CT.Lakshmanan 13.

  • DEPTH OF FOCUS
  • Shallow focus Earthquakes
    • < 70 km deep
  • Intermediate focus earthquakes
    • 70 km ~ 300 km
  • Deep focus earthquakes
    • > 300 km

Prepared by CT.Lakshmanan 14. Magnitude Vs Intensity

  • The magnitude of an earthquake is determined instrumentally and is more objective measure of its size
  • Intensity of an earthquake is a subjective parameter based on assessment of visible effects. It depends on factors other than the actual size of the earthquake

Prepared by CT.Lakshmanan 15. Prepared by CT.Lakshmanan 16. M > 8 Great Very great 7-7.9 Major Great 6-6.9 Strong Moderate 5-5.9 ModerateModerate 4-4.9 LightSlight 3-3.9 Minor Slight M < 3 Microearthquake EARTHQUAKE MAGNITUDE CLASS USGS IMD Prepared by CT.Lakshmanan 17. MagnitudeAnnual Average No. M> 8 2 7-7.9 20 6-6.9 100 5-5.9 3000 4-4.9 15,0003-3.9 >100,000 GLOBAL EARTHQUAKE OCCURRENCE Prepared by CT.Lakshmanan 18. SEISMIC WAVES

  • Body Waves
  • Surface waves
    • Body Waves
      • Primary waves P-waves
      • Secondary waves S-waves
    • Surface Waves
      • Love waves
      • Rayleigh waves

Prepared by CT.Lakshmanan 19. Prepared by CT.Lakshmanan 20. Prepared by CT.Lakshmanan 21. More than 60 % area is earthquake prone. Zone V12 % Zone IV18 % Zone III26 % Zone II 44 % IS 1893:2002 Prepared by CT.LakshmananFig. courtesy: nicee 22. Prepared by CT.Lakshmanan 23. Casualties during past events ( 1988 ) (1993) (1997) (1999) (2001) (1991) Where(when?) ? Prepared by CT.Lakshmanan 24. Earthquake Do Not Kill People

  • Improperly Designed Structures Do!

Prepared by CT.Lakshmanan 25. Prepared by CT.Lakshmanan 26. Prepared by CT.Lakshmanan 27. Prepared by CT.Lakshmanan 28. Earthquake Design Philosophy Prepared by CT.Lakshmanan 29.

  • IMPORTANT CONSIDERATIONS TO MAKE ABUILDING EARTHQUAKE RESISTANT
  • Configuration
  • Ductility
  • Quality control
  • Base Isolation
  • Passive Energy Dissipating Devices
  • Active Control Systems

Prepared by CT.Lakshmanan 30. A terminally ill patient , however effective the medication, may eventually die. Similarly, a badly configured building Cannot be engineered for an improved performance beyond a certain limit. 1. Configuration Prepared by CT.Lakshmanan 31. Prepared by CT.Lakshmanan 32. Regular Configuration

  • Regular configuration is seismically ideal. These configurations have low heights to base ratio, symmetrical plane, uniform section and elevation and thus have balanced resistance.

These configurations would have maximum torsional resistance due to location of shear walls and bracings. Uniform floor heights, short spans and direct load path play a significant role in seismic resistance of the building. Prepared by CT.Lakshmanan 33. Irregular Configuration Buildings with irregular configurationBuildings with abrupt changes in lateral resistance Buildings with abrupt changes in lateral stiffnessPrepared by CT.Lakshmanan 34. Re-entrant corner Prepared by CT.Lakshmanan 35. Discontinuity in diaphragm Stiffness Discontinuity in Diaphragm Stiffness Prepared by CT.LakshmananFLEXIBLE DIAPHRAGM R I G I D D I A P H R A G M OPEN Vertical Components of Seismic Resisting System 36. Out of plane Offsets Shear Wall Out-of-Plane Offsetin Shear Wall Non-parallel system Prepared by CT.LakshmananShear walls 37. Prepared by CT.Lakshmanan 38. ELEVATION IRREGULARITIES 1) Soft-Storey/Pan-caked 2) Set-backs 3) Connections Prepared by CT.Lakshmanan 39. Pancaking Soft storey Prepared by CT.Lakshmanan 40. ELEVATION IRREGULARITIES 4) Pounding 5) Breaks in Columns or Beams 6) Staggered Levels 7) In-fills Prepared by CT.Lakshmanan 41. Open ground storey building (soft storey) Prepared by CT.Lakshmanan 42. Prepared by CT.Lakshmanan 43. Right or Wrong ? Prepared by CT.Lakshmanan 44. Short column effect Prepared by CT.Lakshmanan 45. Prepared by CT.Lakshmanan 46. Ductility L et us first understand how different materials behave.Considerwhite chalkused to write on blackboards andsteel pinswith solid heads used to hold sheets of paper together. Yes a chalk breaks easily !!On the contrary, a steel pinallows it to be bent back-and-forth . Engineers define the property that allows steel pins to bend back-and-forth by large amounts, asductility ; chalk is abrittlematerial. Prepared by CT.Lakshmanan 47. The currently adopted performance criteria in the earthquake codes are the following: i. The structure should resist moderate intensity of earthquake shaking without structural damage.ii. The structure should be able to resist exceptionally large intensity of earthquake shaking without collapse. Prepared by CT.Lakshmanan 48.

  • The strength of brittle construction materials, like masonry and concrete, is highly sensitive to the
  • quality of construction materials
  • workmanship
  • 3.supervision
  • 4.construction methods

Prepared by CT.Lakshmanan 49. Quality control special care is needed in construction to ensure that the elements meant to be ductile are indeed provided with features that give adequate ductility.Thus, strict adherence to prescribed standards of construction materials and construction processes is essential in assuring an earthquake-resistant building.Prepared by CT.Lakshmanan 50. El ements of good quality control. 1. Regular testing of construction materials at qualified laboratories (at site or away)2. P eriodic training of workmen at professional training houses, and 3.On-site evaluation of the technical work Prepared by CT.Lakshmanan 51. IS CODES IS 1893 (Part I), 2002,Indian Standard Criteria for Earthquake Resistant Design of Structures(5th Revision) IS 4326, 1993,Indian Standard Code of Practice for Earthquake Resistant Design and Construction of Buildings(2nd Revision) IS 13827, 1993,Indian Standard Guidelines for Improving Earthquake Resistance of Earthen Buildings IS 13828, 1993,Indian Standard Guidelines for Improving Earthquake Resistance of Low Strength Masonry Buildings IS 13920, 1993,Indian Standard Code of Practice for Ductile Detailing of Reinforced Concrete Structures Subjected to Seismic Forces Prepared by CT.Lakshmanan 52. Base isolators Prepared by CT.Lakshmanan 53. Prepared by CT.Lakshmanan 54. While Hazards Are Inevitable, Each Hazard Need Not ConvertInto A Disaster As What Comes In Between IsThe Culture of Safety And Prevention Let us Work Together toBuild a Culture of Prevention ! Prepared by CT.Lakshmanan