engleski

Passive Supplemental Damping Systems

The paper offers a design approach for earthquake resistant structures whose aim is to reduce seismic action by dynamic modifications of structures without modifying structural stiffness. Dynamic properties of structures can be modified by supplemental damping systems that dissipate seismic energy and/or systems designed to limit the transmission of seismic energy to the main structure by isolation of the main structural elements. An energy concept is introduced in order to explain dynamic modifications in structures. Main damping mechanisms used in energy dissipation are viscous and hysteretic damping. Hysteretic damping is a very important damping mechanism which appears under plastic deformation. Viscous damping is a result of material viscosity and is proportional to velocity and frequency. The model of viscous damping is often used to replace other damping mechanisms by using equivalent viscous damping. Viscoelastic dampers develop a restoring force as well as a damping force so both types of damping mechanisms are present. Supplemental damping systems can be divided into three categories: passive, active and semi-active systems. Passive energy dissipating systems can be displacement-activated, velocity-activated and motion-activated devices. Active systems are more complex than passive systems because they require a continuous external power source and additional maintenance to operate properly. Base isolation decouples the structure from the horizontal components of the ground motion by interposing structural elements with low horizontal stiffness under the superstructure. It enables a period shift towards large values and gives the structure a fundamental frequency that is much lower than both its fixed-base frequency and the predominant frequency of the ground motion. The paper includes passive supplemental damping systems and not base isolation.

supplemental damping systems; passive systems; energy dissipation; viscous dampers; hysteretic dampers; viscoelastic dampers; anti-seismic devices

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