Lead rubber bearing isolator/ Lead bridge bearing/ lead core bearing
Lead Rubber Bearing or LRB is a type of base isolation employing a heavy damping. It was invented by William Robinson, a New Zealander. Heavy damping mechanism incorporated in vibration control technologies and, particularly, in base isolation devices, is often considered a valuable source of suppressing vibrations thus enhancing a building's seismic performance. However, for the rather pliant systems such as base isolated structures, with a relatively low bearing stiffness but with a high damping, the so-called "damping force" may turn out the main pushing force at a strong earthquake. The video shows a Lead Rubber Bearing being tested at the UCSD Caltrans-SRMD facility. The bearing is made of rubber with a lead core. It was a uniaxial test in which the bearing was also under a full structure load. Many buildings and bridges, both in New Zealand and elsewhere, are protected with lead dampers and lead and rubber bearings.
Name: LRB bearing
Brand : JINGTONG
CR suit temperaturer : CR -25°C~+60°C
NR suit temperaturer: NR
CR suit temperaturer : CR -25°C~+60°C
During the earthquake, the un-isolated building will vibrate back and forth in varying directions due to the inertial forces and result in deformation and damages of the building. In contrast, the base isolated building will also displace but remains its original shapes and avoid damages - that is because the lead rubber bearing effectively dissipates the inertial force upon the building, extends the building's period of vibration and decrease the acceleration of the building.
The lead plug will slid with laminated rubber during earthquake but convert this energy of movement to heat so that it efficiently reduces the inertial force upon the building, which slow the vibration of the building. Meanwhile, the rubber part will preserve its original shape due to high elasticity
How do base isolators work?
Base isolation is a technique developed to prevent or minimise damage to buildings during an earthquake. It has been used in New Zealand, as well as in India, Japan, Italy and the USA.
A fixed-base building (built directly on the ground) will move with an earthquake's motion and can sustain extensive damage as a result.
When a building is built away (isolated) from the ground, resting on flexible bearings or pads known as base isolators, it will only move a little or not at all during an earthquake.
The rubber provides flexibility through its ability to move but return to its original position. At the end of an earthquake, if a building hasn't returned to its original position, the rubber bearings will slowly bring it back. This might take months, but it will return to its original position.
Lead was chosen because of its plastic property - while it may deform with the movement of the earthquake, it will revert to its original shape, and it is capable of deforming many times without losing strength. During an earthquake, the kinetic energy of the earthquake is absorbed into heat energy as the lead is deformed.
Using layers of steel with the rubber means the bearing can move in a horizontal direction but is stiff in a vertical direction.
Another method for controlling seismic damage in buildings is the installation of seismic dampers. In this case, the dampening is provided by a lead-based device that looks very similar to a car damper (shock absorber).
Ground movement forces the lead to pass through a narrow gap. When the direction of movement changes, the flow of lead is reversed. The principle is still the same as the lead rubber bearing, with kinetic energy being converted into heat energy, thereby preventing the building absorbing the kinetic energy.
1.Stiff and strong in vertical direction but flexible in horizontal direction.
2.Absorb earthquake-generated force by changing the bearing's shape.
3.Allow the buildings to retain their original shapes and position owing to the high elastic force of rubber.
4.Capable to adjust damping amount just by changing the number of lead plugs.
5.Excellent vertical load capacity ranging from 5 tonf to 2000 tonf.
6.Reduce the ground acceleration by extending the structure vibration period.
7.High durable and elasticity of the rubber part - not suffer any damages during and after earthquake.
8.Easy to install without a separated damper.
10.With stable bilinear behavior shown as the above pictures
|Permanent Service Loading N/mm2||Ultimate shear strain (%)|
Hengshui Jingtong Rubber Co., Ltd., is an experienced and professional manufacturer of construction engineering products. It is located in Hengshui City, Hebei Province, China.
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