1. BASICS OF DYNAMICS AND ASEISMIC DESIGN
MUTHUMINALR
ASSISTANT PROFESSOR
CIVIL DEPARTMENT

2. OBJECTIVE:
The main objective of this Subject is to provide a basic knowledge over the reaction of structures due to the action of dynamic loads

3. Elements Of Seismology Response Of Structures To Earthquake
UNITS COVERED
Theory Of Vibrations
Multiple Degree Of Freedom System
Elements Of Seismology
Response Of Structures To Earthquake
Design Methodology

4. THEORY OF VIBRATIONS
Concept of inertia and damping
Types of Damping
Difference between static forces and Dynamic excitation
Degrees of freedom
SDOF idealization
Equations of motion of SDOF System for mass as well as base excitation
Free vibration of SDOF system
Response to Harmonic excitation
Impulse and response to unit impulse
Duhamel integral

5. Introduction to dynamics
Structural analysis is mainly concerned with finding out the behaviour of a structure when subjected to some action.
This action can be in the form of load due to the weight of things such as people, furniture, wind, snow, etc. or some other kind of excitation such as an earthquake, shaking of the ground due to a blast nearby, etc.
Dynamic analysis for simple structures can be carried out manually, but for complex structures finite element analysis can be used to calculate the mode shapes and frequencies.

6. Importance of dynamics
The importance of Structural Dynamics is to find the behaviour of a structure when subjected to some action.
This can be done by means of dynamic loads or vibration.

7. Types and sources Periodic Loading i. Sinusoidal Loading
ii. Stepped Loading
iii. Complex Variation Loading

9. Types of analysis Equivalent static analysis
Response spectrum analysis

10. Types of structural vibration
Free vibration
Forced vibration
Damped vibration
Undamped vibration

11. Types Of Damping Viscous damping Coulomb damping Structural damping
Active damping
Passive damping

12. Degrees of freedom
Single degree of freedom
Two degree of freedom

13. Single degree of freedom
Deals with analyzing the structure which has been provided with a single mass connected to a spring

14. Two degree of freedom
This deals with analyzing the system provided with two masses which is connected to the spring

15. Elements of seismology
Causes of Earthquake
Geological faults
Tectonic plate theory
Elastic rebound
Epicenter
Hypocenter
Primary, shear and Raleigh waves
Seismogram
Magnitude and intensity of Earthquakes
Magnitude and Intensity scales
Spectral Acceleration
Information on some Disastrous earthquakes

16. Elements of seismology
Seismology is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other planet-like bodies. The field also includes studies of earthquake effects, such as tsunamis as well as diverse seismic sources such as volcanic, tectonic, oceanic, atmospheric, and artificial processes (such as explosions).

18. Indian 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
IS 13935, 1993, Indian Standard Guidelines for Repair and Seismic Strengthening of Buildings

19. Indian seismicity

20. Faults

21. Types of waves

22. Intensity

23. Magnitude

24. RESPONSE OF STRUCTURES OF EARTHQUAKE
Response and design spectra
Design earthquake
concept of peak acceleration
Site Specific response spectrum
Effect of soil properties and damping
Liquefaction of soils
Importance of ductility
Methods of introducing ductility into RC structures.

25. Response spectrum
The representation of the maximum response of idealized single degree freedom systems having certain period and damping, during earthquake ground motion.
The maximum response is plotted against the undamped natural period and for various damping values, and can be expressed in terms of maximum absolute acceleration, maximum relative velocity, or maximum relative displacement.

26. Response history analysis
It is an analysis of the dynamic response of the structure at each increment of time, when its base is subjected to a specific ground motion time history.
The response of a structure to ground vibrations is a faction of the nature of foundation soil; materials, form, size and mode of construction of structures; and the duration and characteristics of ground motion.

27. Modal analysis

28. Types of liquefaction Flow Liquefaction Cyclic Mobility
Flow Liquefaction is a phenomenon in which the static equilibrium is destroyed by static and dynamic loads in a soil deposits with low residual strength
Cyclic mobility is a liquefaction phenomenon, triggered by cyclic loading, occurring in soil deposits with static shear stresses lower than the soil strength.

29. Effects of liquefaction
1. Loss of bearing strength 2. Lateral spreading 3. Sand boils 4. Flow failures 5. Ground osculation 6. Flotation 7. Settlement

30. Methods to reduce liquefaction
1. Avoid liquefaction – susceptible soils
2. Build liquefaction – resistant structures
3. Shallow foundation aspects
4. Deep foundation aspects
5. Improve the soil
6. Drainage techniques
7. Verification improvements

31. Soil structure interaction

32. Design methodology
IS 1893, IS and IS 4326 – Codal provisions – Design as per the codes
Base isolation Techniques
Vibration control measures
Important points in mitigating effects of earthquake on structures.