Introduction The naturallyoccurring ground movement, which eventually goes on creating disasters such asfailure of structure and natural phenomenon is known as the Earthquake. Theenergy that is discharged from those seismic activities makes waves.
Thesewaves cause ground movement, which in turn is transmitted to the structure via thefoundation. Depending on the intensity of these vibrations, cracks andsettlement is caused to the structure. Force is induced in structure; because of thisthe resulting damage to the structure increases with the ground motion. Manyengineers introduce ductility to thebuilding (pliable but not losing itstoughness, meaning a building could be deformed during an earthquake but wouldnot collapse upon the people inside it. Imagine an elastic band. Though able towithstand great force, it will eventually break; in the context of thebuilding, the maximum point it can deform before breaking, called the Elasticlimit. Upon reaching the Elasticity limit, cracks form in the building). However,elastic materials are much more expensive to buy which gives a significantdisadvantage to poorer areas.
In addition, elasticity decreases damage byincreasing the strength, giving a disadvantage to the components of thebuilding with less strength.Baseisolation is a frequently adopted earthquake-resistant system. Isolation beingthe separation of a building from its foundations, Basic principle of baseisolation is to differentiate the building from its foundation, so during theseismic action, building is stays unaffected from the ground motion. In otherwords, even though ground moves aggressively, the building will tend to moveideally as a rigid body rather than collapsing. This reduces the floorhastening and storey gliding and so the building components are left lessharmed. In the model, separation is total but practically, there is some correlation between the ground and the building which provides flexibility tothe structure. Any stiff structure will have short period. During the groundmovement, amount of acceleration entrusted in the structure is the same ofground acceleration that results in zero displacement between the structure andthe ground.
In other words, ground and structure will move with equal amount.