Base isolation how does it work

Related content Read about other work to earthquake-proof structures in Seismic engineering. Activity idea In the activity, Best base isolator , students use a physical model to investigate the effectiveness of different properties for base isolators. Useful link To learn more about present developments and thinking around seismic engineering, listen to Dr Geoff Rodgers in this RNZ podcast.

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Yes No. Earthquake Hazards Is Singapore threatened by earthquakes? Can we predict earthquakes? Why does a building on solid bedrock resist better to an earthquake than a building on sediment or reclaimed land? Why does a building with base isolation resist better to an earthquake than a building without base isolation?

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How can we forecast volcanic eruptions? Tsunamis Where is a tsunami most likely to happen? Can Singapore be affected by a tsunami?

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Volcanoes All About Volcanoes What is the difference between magma and lava? Sliding isolators can be implemented in different ways. Pure friction systems use flat stainless-steel plates to introduce the sliding motion. However, this technique has some limitations. Their main disadvantage is due to the geometry of the sliding surface — it can produce large and residual sliding displacements. Friction pendulum systems, based on pendulum motion principles, overcome these issues. As the picture below illustrates, in an earthquake the slider moves along the spherical concave surface of the bearing, helping minimize the motions of the mass caused by seismic activity.

At the end of the earthquake, the gravitational force returns the slider to its original position, minimizing the residual displacement. Many structures, including the Benicia Martinez Bridge, use friction pendulum bearings for base isolation. Through physical demonstration, they wanted to help students understand the concept and effectiveness of this type of base isolation system.

To show the effect of the base isolation on the performance of a structure, the authors used two Quanser one-floor test structures: one with the friction pendulum bearing base isolation system, the other with no base isolation. They compared the top floor accelerations of these structures when exposed to the earthquake motion simulated by the Shake Table II. While they developed the lab experiment for educational purposes, it highlights how effective base isolation strategies could be and why they are used in structures around the world.

Base isolation is very effective in enhancing seismic resistance of structures. It is not, however, as effective against wind disturbances. Base isolation actually lowers the inherent lateral stiffness of a structure, which means that strong winds could result in its large displacement.

To overcome this issue, base isolation is often complemented by tuned mass dampers. The EEW sysytem can predict if an earthquake is going to occur and issue a warning.

Their proposed smart mechatronic base isolation system is turned on and off depending on the load type. The EEW signal would activate the base isolation, but in high winds, it would remain inactive, maintaining the lateral rigidity of the building. As a backup, in case the EEW system failed to issue a signal, the researchers employed a network of accelerometers that could detect ground motions.

If the accelerometer measurements exceeded a certain threshold, the base isolation was engaged independently from the EEW system. To demonstrate the feasibility of their approach, the researchers performed laboratory-scale experiments. Many structures are being built making use of this technique, while many others are in the design stage or under building phase. Almost all the finished buildings and those under construction utilize rubber isolation bearings in the isolation system. Base isolation right from the very start depended on two mainstays: heavy damping and frequency separation.

But not much attention was paid to the heavy damping kind which is a well-built association between a substructure and superstructure. Then decoupling them with the aid of connections is not good.