Seismic isolator with variable curvature

Abstract

A seismic isolator includes a slider, and a path with non-fixed curvature; the path is positioned on a base; the slider is placed on the path, and bears the weight of a super-structure; the path with non-fixed curvature can be a smoothly curved surface; a layer of ductile material with high compressibility is mounted between the slider and the path with non-fixed curvature; therefore, when an earthquake occurs, the slider will slide on the path with non-fixed curvature to produce vibration isolation effect for the superstructure; loading capacity of the isolator increases, and resonance between the isolator and low-frequency earthquakes is prevented.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a seismic isolator with variable curvature, more particularly one, which doesn't easily resonate with low-frequency earthquakes, and has increased loading capacity, and can function more effectively. [0003] 2. Brief Description of the Prior Art [0004] When an earthquake occurs, the violent ground motion is the major reason that damages a structure. The violent ground motion is passed on from the base of the structure to the super-structure. In seismic isolation technology, special isolation bearings are installed between the base and the super-structure to reduce the amount of movement passed on from the ground to the super-structure, thus reducing the seismic force, to which the structure is subjected. Common seismic isolation bearings are roughly grouped into two types, namely, sliding bearings and elastomeric bearings. [0005] Friction pendulum system (FPS) is the most widely used ...

AI Technical Summary

Benefits of technology

[0010] It is the main objective of the invention to provide a seismic isolator with variable curvature to overcome the above-mentioned problems. The seismic isolator of the present invention includes a slider, and a path with non-fixed curvature. The path is placed on a base. The slider touches the path, and bears the weight of a super-structure. The path with non-fixed curvature can be a smoothly curved surface. And, a layer of ductile material with high compressibility is attached to the slider and placed between the slider and the path of non-fixed curvature. Therefore, when an earthquake occurs, the slider will slide on the path of non-fixed curvature to produce a seismic isolation effect for the super-structure. At the same time, this invention increases loading capacity of the isolator, and prevents resonance with low-frequency earthquakes.

Problems solved by technology

When an earthquake occurs, the violent ground motion is the major reason that damages a structure.

However, it can also be found that the structure with the sliding isolation system will be subjected to even greater earthquake effect than the fixed base when the excitation frequency is lower than 0.6 Hz.

Therefore, we can conclude that a conventional sliding isolation system can effectively reduce vibration only when the excitation frequency is higher than the isolation frequency (0.4 Hz); a conventional sliding isolation system will cause an adverse effect, when the earthquake contains low-frequency components.

Furthermore, recent theories and experiments on seismic isolation technology have revealed that sliding isolation systems can't effectively reduce vibration in a near-fault earthquake because it is affected by the low-frequency pulse waves characterizing a near-fault earthquake.

Because the rollers are in point-contact with the curved grooves, there can be material damage caused by stress concentration.

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