Elastomeric seismic protection isolator -------The technical tested parameters designing of elastomeric seismic isolation

Elastomeric seismic protection isolator

-------The technical tested parameters designing of elastomeric seismic isolation

Key words: Elastomeric seismic protection isolator, lead rubber bearing, LRB, high damping rubber bearing, seismic isolation,rubber seismic isolator, rubber isolation bearings

Elastomeric Isolators are widely used on bridge and buildings now, there are linear natural rubber bearing, lead rubber bearing, high damping rubber bearing ,which are all laminated elastomeric seismic protection isolators.

The first important technical performance of the elastomeric isolators is vertical compress capacity. The vertical capacity by testing, the main testing data is vertical stiffness and vertical deformation performance, which are tested under rated vertical loading . The vertical stiffness is the main parameter show the vertical capacity of elastomeric isolators, the larger of the vertical stiffness,The smaller deformation under external force. the better earthquake shock absorption effect can be achieved. The elastomeric seismic protection isolator structure parameters, rubber material characteristics, and loading method can effect on the vertical stiffness.

1.The structure of elatomeric isolator can effect on the vertical stiffness, such as the dimensions of diameter, thickness and height,when the dimensions and height are larger, the vertical stiffness is larger, but when the dimensions are larger, the rubber  seismic protection, the deformation capacity will be reduced, so we should  consider the dimensions depended on the project requests, not the bigger isolator is  the better suitable.

2. The rubber characteristics effects on the vertical stiffness of elastomeric seismic protection isolators. The rubber material hardness and shear modulus effect on the rubber seismic protection vertical stiffness and movement deformation. The bigger hardness, the bigger vertical stiffness, but the movement deformation will be smaller, the bigger shear modulus, the bigger vertical stiffness, but the same result is the movement deformation will be smaller, it is not good the big displacement requests, so we have to consider suitable hardness and shear modulus of the rubber material.

3. The vertical stiffness of isolation rubber bearings is related to the loading method. Under static or low-frequency conditions, the stiffness of the bearings is high, but under high-frequency conditions, the stiffness of the bearings will decrease. This is due to the influence of internal friction and material damping of the rubber material.

The horizontal  performance of rubber isolation bearings refers to their performance under horizontal loads, which is mainly determined by factors such as bearing stiffness and damping ratio.Under the horizontal loading, the stiffness of elastomeric seismic isolation changes.

4. The damping ratio effect on the horizontal performance of rubber seismic protection isolator. The damping rate is another important key factor of seismic rubber protection. A higher damping ratio can reduce the impact force during earthquakes. By designing the internal structure, material selection, and geometric structure, the damping ratio of elastomeric seismic protection isolator  can be increased, thereby improving the performance of isolation bearings.

In summary, we can see that except designing dimension of the elatomeric seismic protection isolator, the material choose and designing structure from  rubber isolator manufacturer are the most important factors to effect the performance and capacity of the seismic isolator. Testing and inspection before production are important during the production process.