- Seismic Isolators
- Structural Bearings
- Expansion Joints
- Tunnel Segment Gaskets
- Dilatation Profiles
Arsan Atlas® Lead Core Rubber Isolator Features and Working Principles
Arsan ATLAS® Lead Rubber Bearings are made of rubber with a lead core in order to provide additional stiffness, uniform deformation and additional damping for an adequate level of energy dissipation.
- The period of vibration of the building is lengthened sufficiently to reduce the force response .
- Prevents the occurrence of resonance, which could lead to severe damage or even collapse of a structure.
- Provides an adequate level of energy dissipation in order to control the displacements that could otherwise damage other structural members.
Rigidity for Non-Seismic Loads
- Adequate rigidity for non-seismic loads (e.g. wind and braking) while accommodating thermal, creep, and other shortening effects.
- Recentring capabilities after the occurrence of a severe earthquake so that no residual displacements can disrupt the serviceability of the structure.
Arsan ATLAS® Lead Rubber Bearings are designed in accordance with seismic isolation principles.
Force-displacement graph showing the hysterical loop and energy dissipation capacity in a lead-core rubber insulator
Lead core that has sufficient energy dissipation capacity decreases lateral displacement on seismic isolator. LRB has nonlinear force-displacement behavior like hysteretic dampers. As lead core is exposed ta shear force causing nonlinear deformation from steel reinforcing layers, it dissipates energy in hysteretic loop after yielding sa Arsan ATLAS® LRB achieve an equivalent viscous damping coefficient between and .
The amount of dissipated energy by lead rubber bearing is equal ta the area under the graph of hystereticloop. Far each loop, kinetic energy is dissipated and turns ta heat energy. Rubber behaves linear up ta strain rate between %1 DO and 0. Thus, the internal rubber layers provide great flexibility in lateral direction with low shear modulus.
Seismic Isolation and Purpose
Seismic isolation principle is ta isolate the superstructure from substructure with a bearing that vertically stiff but horizontally flexible. This flexibility lengthens the fundamental period of the isolated building and reduces the seismic forces in the superstructure..
When an isolated structure is subjected ta an earthquake, the deformation occurs in the isolators rather than the substructure elements. The effects of earthquake forces on the structures can be decreased with this method since seismic isolators dissipate energy ta limit relative displacements. in the economic way, that system allows ta use smaller sections far structural elements.
Seismic behavior of conventional vs seismic isolated structures
lncreasing natural period of the structure causes the increase in displacements and the effective reduction in floor accelerations. LRB systems have an energy dissipation mechanism ta introduce a significant level of damping into the structure ta limit displacements ta suitable levels.
The system must be sufficiently stiff far structural stability un der service conditions such as wind-induced farces, temperature effects, shrinkage and creep effects.
Seismic isolation systems ensure to
- Resist not only seismic conditions but also service conditions including lateral and vertical loads.
- Have adequate flexibility ta sustain the required natural period of structure.
- Move to its original position after the earthquake.
- Dissipate energy effectively; otherwise earthquake load effects may exceed ultimate load capacity of structural and nonstructural elements.
Arsan ATLAS® LRB can be designed according to international specifications for project requirements. Commonly used specifications are listed below:
- EN 15129 Anti-Seismic Devices with EN 1337 Structural Bearings Standard
- AASHTO Guide Specifications for Seismic lsolation Design
- ASCE 7-16 Minimum Design Loads for Buildings and Other Structures
- Turkish Building Earthquake Code 2018
ARSAN produces Lead Rubber Bearing (LRB) with European Conformity (CE) certification obtained from Materials Testing and Research lnstitute (MPA Karlsruhe).
CE certifies that the product meets ali the requirements of the relevant European Standard in design and manufacturing of the product.