About the principle of LNG storage tank isolation -1

I will tell you about the isolation principle of LNG tanks today. The LNG storage tank base isolation structure system refers to a structural system formed by providing a certain isolation device between the bottom of the structure and the base surface. It consists of three parts: the superstructure, the isolation device and the lower structure.

The isolation device can make the structure slide flexibly on the base surface, and the natural vibration period of the structural system becomes longer, so that the basic natural vibration period of the structure deviates from the excellent period of seismic ground motion, and is isolated from the ground motion that may cause damage, and at the same time The energy consuming material or device provides an appropriate damping to suppress excessive displacement caused by increased structural flexibility.

In the LNG cryogenic tank isolation structure, there are three main factors that have an important impact on the seismic response of the building: the basic period of the structure, the damping ratio of the isolated material and the horizontal stiffness of the isolation pad. The isolation design has the following characteristics: Increase the structural natural vibration period. The degree of structural damage caused by earthquakes depends mainly on the proximity of the vibration period of the structure to the excellent period of the earthquake. The isolation technology can effectively reduce the natural vibration frequency of the structure, avoid the seismic excellence cycle as much as possible, and avoid resonance to reduce the seismic response of the structure.

Increase structural damping. Through theoretical analysis, it can be obtained that the natural vibration period of the damped structure increases slightly with the increase of the damping ratio. The damping ratio of ordinary concrete structures is generally between 2% and 5%. Seismic isolation devices such as lead-core rubber isolation bearings can provide additional damping of 10% to 30% for the structure. Studies have shown that the increase of structural system damping can effectively control the displacement response of structures under strong earthquakes.