NPTEL Video Course on Geotechnical Earthquake Engineering

Transcription

1 NPTEL Video Course on Geotechnical Earthquake Engineering by Prof. Deepankar Choudhury Professor, Dept. of Civil Engg., Indian Institute of Technology (IIT) Bombay Powai, Mumbai , India. URL: Lecture 1

2 Course Outline This course on Geotechnical Earthquake Engineering introduces the fundamental concepts of earthquake engineering related to geotechnical problems, principles of earthquake, wave propagation, dynamic soil properties, liquefaction and seismic design of various geotechnical structures. This course focuses on seismic hazard analysis which includes both Probabilistic Seismic Hazard Analysis (PSHA) and Deterministic Seismic Hazard Analysis (DSHA), followed by site response analysis. Also, behaviour of various geotechnical structures such as shallow and deep foundations, retaining structures, slopes, ground anchors, waterfront retaining structures, reinforced soil-wall, tailing dam due to earthquake loading are discussed with reference to codal provisions. The course material on Geotechnical Earthquake Engineering will be very useful to the post-graduate students, researchers, teachers and practitioners. A number of selected problems will be solved to illustrate the concepts clearly.

3 Course Contents Introduction, Basic Vibration theory, Engineering Seismology, Strong Ground Motion, Wave Propagation, Dynamic Soil Properties, Seismic Hazard Analysis, Site Response Analysis, Dynamic Soil- Structure Interaction, Applications of Earthquake Engineering to various Geotechnical Engineering Problems like Retaining Walls, Foundations, Anchors, Piles, Tailing Dams, Landfills, Slopes, Waterfront Retaining Walls/Sea Walls, Reinforced Soil-Walls, Liquefaction, Hazard Mapping etc.

4 Course Modules Total about NINE (9) Modules: Module 1: Introduction to Geotechnical Earthquake Engineering Module 2: Basics of Vibration Theory Module 3: Engineering Seismology Module 4: Strong Ground Motion Module 5: Wave Propagation Module 6: Dynamic Soil Properties Module 7: Seismic Hazard Analysis Module 8: Site Response Analysis Module 9: Seismic Analysis and Design of Various Geotechnical Structures

5 Pre-Requisite Soil Mechanics / Geotechnical Engineering (Mandatory) Soil Dynamics (Optional) Audience Post-Graduate (High Caliber Bachelors, Masters and PhD) Students, Teachers, Practitioners, Designers, Academicians, Decision Makers

6 References 1. Steven L. Kramer, Geotechnical Earthquake Engineering, Prentice Hall Inc. 2. Robert W. Day, Geotechnical Earthquake Engineering Handbook, McGraw Hill, New York. 3. Ikuo Towhata, Geotechnical Earthquake Engineering, Springer- Verlag Heidelberg. 4. Kenji Ishihara, Soil Behaviour in Earthquake Geotechnics, Oxford University Press, USA. 5.Shamsher Prakash, Soil Dynamics, McGraw-Hill Book Company. 6. Milutin Srbulov, Geotechnical Earthquake Engineering: Simplified Analyses with Case Studies and Examples, Springer-Verlag. 7. IS 1893, Indian Standard Criteria for earthquake resistant Design of Structures. ADDITIONAL READINGS (MUST) Journal and Conference papers in the area of Geotechnical Earthquake Engineering.

7 Module 1 Introduction to Geotechnical Earthquake Engineering

8 Effects of Earthquake Devastating effects of earthquakes due to failure of structure Earthquake never kills, but damage of structures during earthquake due to incorrect or insufficient design and constructions kills

9 Effects of Earthquake Devastating effects of earthquakes due to failure of soil beneath Structure is safe, but it has settled down by huge amount, due to failure of ground beneath. Buildings dilapidated because of failure of soil beneath

10 Effects of Earthquake Devastating effects of earthquakes due to landslides and rockslides Fig. Landslides in Sikkim during 2011 earthquake Fig. Rockslides in Sikkim at different road streches

11 Effects of Earthquake Tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake. Tsunami is a Japanese word with the English translation, "harbor wave ("tsu," means harbor, while "nami," means "wave ) Figures showing disasters due to Tsunami

12 Principal Types of Earthquake Damage Structural Caused by excessive ground shaking Strongly influenced by local soil conditions

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16 Ground Shaking: Shakes structures constructed on ground causing them to collapse Liquefaction: Conversion of formally stable cohesionless soils to a fluid mass, causing damage to the structures Landslides: Triggered by the vibrations Retaining structure failure: Damage of anchored wall, sheet pile, other retaining walls and sea walls Fire: Indirect result of earthquakes triggered by broken gas and power lines Tsunamis: large waves created by the instantaneous displacement of the sea floor during submarine faulting

17 Damage due to Earthquakes Earthquakes have varied effects, including changes in geologic features, damage to man-made structures and impact on human and animal life. Earthquake Damage depends on many factors: The size of the Earthquake The distance from the focus of the earthquake The properties of the materials at the site The nature of the structures in the area

18 Ground Shaking Frequency of shaking differs for different seismic waves. High frequency body waves shake low buildings more. Low frequency surface waves shake high buildings more. Intensity of shaking also depends on type of subsurface material. Unconsolidated materials amplify shaking more than rocks do. Buildings respond differently to shaking depending on construction styles, materials Wood -- more flexible, holds up well Earthen materials, unreinforced concrete -- very vulnerable to shaking.

19 Collapse of Buildings

20 Collapse of Buildings June 28th (Mon), :13 pm M7.1, D=0km (Fukui Earthquake, 1948) Death Toll: 3,769 Injured: 22,203 Collapse Ratio of Houses: almost 100% (The Area of South- North 20km by East- West10km of Fukui Plain) Damage to Pile-Heads of Hokuriku Haiden Building. (Shear Cracks)

21 Collapse of Buildings (Fukui Earthquake, 1948) Damage to the Pile Foundations of Hokuriku-Haiden Building caused by the 1948 Fukui Earthquake Settlements of the First Floor Cracks at the Column-Heads of the Second Floor and the Floor Slabs of the First Floor

22 Soft first story/inadequate shear strength Loma Prieta earthquake damage in San Francisco. The soft first story is due to construction of garages in the first story and resultant reduction in shear strength. (Photo from: On October 17, 1989, at 5:04:15 p.m. (P.d.t.), a magnitude 6.9 (moment magnitude; surface-wave magnitude, 7.1)