“Base isolation and Seismic Consideration in Civil Engineering”.. Dr M.K.RATH, Professor Structural Engineering Department of civil engineering Centurion university of technology and management

CONTENT.. INTRODUCTION SEISMIC FORCE Different Seismic Zones In India MAGNITUDE AND INTENSITY OF EARTHQUAKE HAZARDS DUE TO EARTHQUAKE LIQUEFACTION OF SOIL PREVENTION OF LIQUEFACTION EARTHQUAKE-RESISTANT DESIGN EFFECT OF BASE ISOLATION METHODS SEISMIC DAMPERS

INTRODUCTION An earthquake (also known as a quake, tremor or temblor) is the perceptible shaking of the surface of the Earth, resulting from the sudden release of energy in the Earth's crust that creates seismic waves. These produce surface waves, which cause vibration of the ground and as a result the super structure is collapsed.

SEISMIC FORCE Seismic Forces is generated due to Earthquake. Earthquake causes shaking of the ground. So a building resting on it will experience motion at its base.

DIFFERENT SEISMIC ZONE IN INDIA

MAGNITUDE AND INTENSITY OF EARTHQUAKE The Magnitude (M) is a quantitative measure of its strength in terms of energy released . INTENSITY The intensity of an earthquake is measured qualitatively in terms of damages caused by it at a particular location. In general, larger the earthquake, greater is the intensity. Magnitude of an earthquake is a measure of its size. While intensity is an indicator of the severity of shaking generated at a given location.

HAZARDS DUE TO EARTHQUAKE Liquefaction of Soils Ground Shaking Surface Rupture Landslides Lateral Spreading Shear Failure of Foundation Settlements of Structures Failure of Retaining Wall Tsunamis

LIQUEFACTION OF SOIL Soil liquefaction describes a phenomenon whereby a saturated or partially saturated soil substantially loses  strength  and  stiffness in response to an applied stress, usually   earthquake shaking or other sudden change in stress condition, causing it to behave like a liquid.

PREVENTION OF LIQUEFACTION Providing Deep Foundation Compaction of Soil Replacing the Liquefaction Soil Grouting The Soil Ground Water Pumping Drainage of Soil Providing Stone Columns

EARTHQUAKE-RESISTANT DESIGN Objective of Earthquake-Resistant Design is to make such buildings that can resist effect of ground motion and would not collapse during the strong Earthquake. All the components of the structure and foundations are designed to resist inertia forces in addition to the normal forces. All the walls must be jointed properly, so that they can act together against the earthquake shaking at the time of seismic force transferring to the ground.

BASE ISOLATION METHOD The idea behind the Base Isolation is to detach (isolate) the building from the ground in such a way that earthquake motions are not transmitted up through the building, or at least greatly reduced. If a building is rested on flexible pads that offer resistance against lateral movements, then some effect of the ground shaking will be transferred to the building above. If the flexible pads are properly chosen, the forces induced by ground shaking can be a few times smaller than that experienced by the building built directly on ground.

EFFECT OF BASE ISOLATION METHOD

SWING BEAM

BASE ISOLATION METHOD

SEISMIC DAMPERS Seismic Dampers are fixed in place of structural elements as diagonal braces. They absorb a part of seismic energy when it is transmitted through them. TYPES OF SEISMIC DAMPERS: a. Viscous Dampers Energy is absorbed by silicone-based fluid passing between piston-cylinder arrangement.

VISCOUS DAMPER Below the Bridge from the foundation level of the super structure

SEISMIC DAMPERS . Friction Dampers Energy is absorbed by surfaces with friction between them rubbing against each other .

Friction Dampers

SEISMIC DAMPERS . Yielding Dampers Energy is absorbed by metallic components.

Yielding Dampers

CONCLUSION Seismic base isolation method has proved to be a reliable method of earthquake resistant building. The success of this method is largely attributed to the development of isolation devices and proper planning. Adoptable isolation systems are required to be effective during a wide range of seismic events.

REFFERENCE.. Wikipedia WWW.youtube.com From Google about base isolation..