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INTRODUCTION TO EARTHQUAKE ENGINEERING

INTRODUCTION TO EARTHQUAKE ENGINEERING. Plate movement Type of faults Wave motion Energy release Urban earthquake risk Structural performance level Evaluation approach. Sequence. 8/10. Large Earthquakes. Elastic Rebound Theory. Indian Plate. Historical Earthquakes in the Himalaya.

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INTRODUCTION TO EARTHQUAKE ENGINEERING

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  1. INTRODUCTION TO EARTHQUAKE ENGINEERING

  2. Plate movement Type of faults Wave motion Energy release Urban earthquake risk Structural performance level Evaluation approach Sequence

  3. 8/10

  4. Large Earthquakes

  5. Elastic Rebound Theory

  6. Indian Plate

  7. Historical Earthquakes in the Himalaya

  8. Southern Asia

  9. Plate Movement 4-5 m slip @1 cm/yr =4-500 years

  10. Indian Plate Himalayas Tibetan Plateau

  11. Indian Plate Tibet

  12. Indian Plate Tibet

  13. Indian Plate Tibet

  14. critical stress Tibet

  15. 2-20 m surface rupture 1.5 m co-seismic subsidence great earthquake Tibet 4-10 m the longer the inactivity the bigger the 'quake’

  16. Faults Through the study of faults and their effects, much can be learned about the size and recurrence intervals of earthquakes. Faults also teach us about crustal movements that have produced mountains and changed continents. Stresses often continue to build until they exceed the strength of the bond in that section of crust. The rock then breaks, and an earthquake occurs, sometimes releasing massive amounts of energy. Faults vary in length from a few centimeters to hundreds of kilometers across. Displacements of one side of the fault over the other vary from fractions of a meter to many kilometers. In many cases the displacement is not confined to a single fracture but is distributed throughout a fault zone. Many faults do not rupture the surface, but when the surface is broken, the fault line is visible as a fault trace or outcrop. Contd…

  17. Faults Vertical or horizontal movement may occur along a fault plane. Sometimes both vertical and horizontal movement occur simultaneously. Faults are named according to the type of movement that has occurred. The term slip is used to indicate relative displacement across the fault. When the movement along the fault plane is generally horizontal, it is a strike-slip fault. These are also called lateral faults. Offset streams are found along active strike-slip faults. A transform fault is a zone of lateral movement along which the ridges and rises have been offset and along which the displacement suddenly stops or changes form and direction. When the movement along the fault plane is predominately vertical, it is a dip-slip fault. There are sub-classifications within this category. Contd…

  18. Faults A normal fault occurs when the earth above the fracture moves down in respect to the earth below the fracture. A reverse fault occurs when the rocks above the fracture move up with respect to those below. A reverse fault with an angle of less than 45 degrees is called a thrust fault. Thrust faults are generally characterized by older rocks resting on younger rocks, although in some cases younger rocks may be thrust over older rocks.

  19. Left Lateral Fault

  20. Left Lateral Fault

  21. Left Lateral Fault

  22. Right Lateral Fault

  23. Right Lateral Fault

  24. Right Lateral Fault

  25. Normal Faulting

  26. Normal Fault

  27. Thrust Faulting

  28. Thrust Fault

  29. Wave Motion

  30. Wave Path

  31. Energy Release

  32. Energy Release

  33. HAZARDS EXPOSURE VULNERABILITY LOCATION ELEMENTS OF URBAN EARTHQUAKE RISK RISK

  34. Joe’s Joe’s Great Food! Great Food! Serviceability ImmediateOccupancy CollapsePrevention 0% Damage 99% Structural Performance Levels

  35. Serviceability Level • Negligible structural and nonstructural damage • Utilities are available • Facility is available for immediate re-use • Repair costs are minimal to nil Joe’s Great Food!

  36. Immediate Occupancy Level • Negligible structural damage • Minor nonstructural damage • Building is safe to occupy but may not function • Limited interruption of operations • Repair Cost < 15% Joe’s Great Food!

  37. Immediate Occupancy

  38. Life-Safety

  39. Collapse Prevention Level • Extensive structural and non-structural damage • Extended loss of use • Repair may not be practical • Repair costs >> 30%

  40. Collapse Prevention

  41. Collapsed

  42. Joe’s Joe’s Great Food! Great Food! Global Response & Performance Loading Severity Structural Displacement D

  43. 1- Select Hazard Level 4- DetermineDrift & ComponentDemands 5- Determine Performance -1 10 Immediate Occupancy Joe’s Beer! Food! -2 10 Annual Probability of Exceedance D -3 10 Collapse margin > 1.0 Lateral Force - V -4 10 Joe’s Life Safety margin = 1.33to 1.5 Collapse Prevention margin = 1.0 Great Food! -5 10 0 .5 1.0 1.5 2.0 2.5 DLS DCP 0 Spectral Acceleration at Period T Lateral Displacement - D t 2- Determine groundMotion Sa 3- Run Analysis Evaluation Approach 6- Pass or Fail Criterion evaluated on component by component basis

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