# Oscillation Control Theory

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With the increasing demands for the durability, reliability, safety, and serviceability of structures, the vibration control theory and practices are leading for more and more concentration in civil engineering structures with a lot of practice being executed on current infrastructures such as high rise buildings, off-shore platforms and long span suspension bridges. As we know vibration means mechanical oscillations about an equilibrium point. The oscillation can be cyclic or non-cyclic. The control of vibrations is necessary for machines, space shuttle, aircrafts, ships floating on water etc. With the innovations in engineering the vibration reduction technique has found its way to civil engineering and infrastructure field. Currently innumerable…show more content…
If the energy or vibration acting on the structure by wind and earthquake load is completely dissipated in any way the structure will vibrate less. As we all know some energy is naturally released in the structures via number of mechanisms like stressing internally, friction and plastic deformation. The total damping is about 5% in almost all large modern structures. Hence to dissipate the larger energy and to control the vibrations, artificial damping devices are installed in many tall structures all over the world. There are a number of methods to control the vibrations which include passive method, active method, semi-active method and hybrid method. The factors that govern the choice of a particular form of device to control vibrations are effectiveness, compactness and mass, initial cost, maintenance cost, maintenance supplies and…show more content…
It is also known as pendulum damper as it is acts as a pendulum during a vibration and utilizes the same characteristic and properties. It is extensively used for the control of vibrations in mechanical operated systems. In the current era TMD theory is been utilized to control the vibrations of elevated buildings and other civil engineering structures. The additional mass system of the TMD is designed such that the natural frequency, which depends on the stiffness and mass, tuned to that of the main structure. When the frequency of that particular structure gets excited due to vibrations the TMD will resonate adjacent to its phase and move against the motion of the structure and thereby reducing its response. Then, the surplus energy that builds up in the structure due to the vibration can be transferred to the additional mass of the TMD and is released by the dashpot due to relative movement of the dashpot between them at a later Stage. The additional mass of the secondary system varies from 0.5-10% of the total dead load of the structure. When the structure vibrates due to earthquake, it contains a many number of frequencies, hence in recent day’s multiple tuned mass dampers (MTMD) has been adopted to reduce the motion induced