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Building isolation
LNR natural rubber bearing — image 1
LNR natural rubber bearing — image 1

LNR natural rubber bearing

Natural rubber isolation bearing for building structures.

The laminated rubber and steel assembly provides vertical support and horizontal restoring action. The bearing forms part of the isolation layer between the supported structure and its foundation or lower structure.

Configuration & selection
Natural rubber isolation
Type I, II and III construction references

For selection, send the design loads, movement requirements and connection drawings. Confirm the model, dimensions and interfaces against your project drawings.

Request product information
Technical information

Applications

Building isolation layers in schools, hospitals, residential buildings and other structures where horizontal flexibility and restoring action are required.

Key features

  • Natural rubber layers provide horizontal flexibility and elastic restoring force.
  • Steel laminations help carry vertical building loads.
  • Can be coordinated with other isolation and damping devices in the overall system.

Technical specifications

LNR natural-rubber configurations are selected by vertical load, effective diameter, rubber height, horizontal and vertical stiffness, displacement and connection details. The catalog includes Type I and Type II dimensional tables.

Detailed technical information

LNR Type I dimensions and performance

Design loads use a reference pressure of 15 MPa for the catalog’s Class C building category (丙类); loads for other building categories require conversion. Types I and II have different body heights.

LNR Type I dimensions and performance
Model Design load (kN) Effective diameter (mm) Body height (mm) Total rubber thickness (mm) S1 S2 Horizontal stiffness (kN/mm) Vertical stiffness (kN/mm)
LNR400 1884 400 156 73 ≥15 ≥5 0.71 1100
LNR500 2944 500 183 92 ≥15 ≥5 0.87 1350
LNR600 4239 600 201 110 ≥15 ≥5 1.05 1650
LNR700 5770 700 241 129 ≥15 ≥5 1.21 2150
LNR800 7536 800 270 148 ≥15 ≥5 1.38 2500
LNR900 9538 900 291 165 ≥15 ≥5 1.55 3200
LNR1000 11775 1000 334 184 ≥15 ≥5 1.72 3800
LNR1100 14248 1100 362 202 ≥15 ≥5 1.91 4300
LNR1200 16956 1200 380 220 ≥15 ≥5 2.09 4700
LNR1300 19900 1300 414 239 ≥15 ≥5 2.26 5700
LNR1400 23079 1400 461 257 ≥15 ≥5 2.45 6500
LNR1500 26494 1500 486 276 ≥15 ≥5 2.62 7300

Source: manufacturer catalog, printed page 53.

LNR Type II dimensions and performance
LNR Type II dimensions and performance
Model Design load (kN) Effective diameter (mm) Body height (mm) Total rubber thickness (mm) S1 S2 Horizontal stiffness (kN/mm) Vertical stiffness (kN/mm)
LNR400 1884 400 156 73 ≥15 ≥5 0.71 1100
LNR500 2944 500 183 92 ≥15 ≥5 0.87 1350
LNR600 4239 600 211 110 ≥15 ≥5 1.06 1650
LNR700 5770 700 257 129 ≥15 ≥5 1.21 2150
LNR800 7536 800 280 148 ≥15 ≥5 1.38 2500
LNR900 9538 900 311 165 ≥15 ≥5 1.55 3200
LNR1000 11775 1000 364 184 ≥15 ≥5 1.72 3800
LNR1100 14248 1100 382 202 ≥15 ≥5 1.91 4300
LNR1200 16956 1200 410 220 ≥15 ≥5 2.09 4700
LNR1300 19900 1300 444 239 ≥15 ≥5 2.26 5700
LNR1400 23079 1400 501 257 ≥15 ≥5 2.45 6500
LNR1500 26494 1500 526 276 ≥15 ≥5 2.62 7300

Source: manufacturer catalog, printed page 54.

Building rubber isolation bearings: principle and types

An isolation layer at the building base or another designed level separates the upper structure from the lower foundation. By isolating or dissipating seismic energy, it reduces transmission to the occupied structure and helps protect occupants, equipment and continued operation. Conventional earthquake resistance primarily relies on the connected structure carrying seismic action; isolation introduces a flexible layer to reduce that action.

The product specification states indicative reductions of 70%–90% in seismic response, equivalent to 1–2 intensity degrees, and 5%–20% construction-cost savings. These indicative benefits depend on the building design and site conditions. The listed applications include lifeline facilities, major projects, ordinary buildings and retrofit strengthening.

Rubber isolators use shear deformation of rubber/steel laminations; friction pendulum bearings dissipate energy by sliding friction and use pendulum geometry for restoring action. Example product sizes include LNR-1000 and LRB-1100.

Building isolation testing

Building isolation bearing evaluation covers vertical compression, horizontal shear stiffness, equivalent damping, cyclic behaviour and rubber material properties. The test documentation includes rubber isolation bearing inspection reports, performance-result tables, force–displacement curves and test-machine records.

Rubber-property evaluation covers hardness, tensile strength, elongation at break, brittleness, compression set, ageing and rubber-to-steel adhesion. Mechanical tests assess the complete bearing under its specified load and displacement conditions.

Building isolation: principle, applications and benefits

An isolation system at the building base converts much of the structure’s lateral shaking into movement of the isolation layer, reducing the seismic energy transmitted to the upper structure. The presentation describes applications in housing, schools, hospitals, public venues, precision-instrument rooms and lifeline facilities in areas of high seismic demand.

  • Potential construction savings: reduced design earthquake action can permit smaller member sections and less reinforcement, subject to the actual structural design.
  • Vertical support: carries the building weight.
  • Restoring function: rubber elasticity supports recovery after wind or earthquake movement.
  • Damping: limits isolated-structure response, particularly horizontal displacement.

Building isolation: types and design benefits

Rubber bearings and elastic sliding bearings can be used independently or together in a combined isolation system. Rubber bearings are available in Type I, Type II and Type III construction forms.

Building isolation bearing types
Type Functions and use
LNR natural rubber Vertical load support and horizontal restoring force.
LRB lead-rubber Vertical load support, horizontal restoring force and damping; can be used as an independent isolation component.
HDR high-damping rubber Vertical load support, horizontal restoring force and damping; commonly combined with supplementary dampers.
Construction cost and use of land

Under the appropriate structural design conditions, isolation can allow the superstructure seismic design intensity to be reduced by 1–1.5 degrees, optimising reinforcement and wall construction and reducing civil construction cost. In medium- and high-intensity regions, controlled design conditions can permit 1–2 additional storeys, improving floor-area utilisation.

Seismic performance objectives

The company’s design presentation describes a reduction in upper-structure seismic response of 1/4–1/8 compared with conventional earthquake-resistant structures, together with a one-level increase in protection. Actual performance depends on the building and isolation-system design.

Performance objectives by earthquake level
Earthquake level Conventional structure Isolated structure
Minor No damage No damage
Moderate Repairable damage Slight damage
Major No collapse Continued use

Hainan Provincial Childcare Comprehensive Service Centre

Building isolation bearings supplied for the Hainan Provincial Childcare Comprehensive Service Centre include natural-rubber LNR1000 bearings and lead-rubber isolation bearings in the 1100 size class.

Jinshan Middle School library reconstruction

LNR natural-rubber and LRB lead-rubber building isolation bearings were supplied for the post-disaster demolition and reconstruction of the Jinshan Middle School library in Wenchang, Hainan.