Headquarters:
mageba sa
Solistrasse 68
8180 Bulach
Switzerland
Tel: +41-44-872 40 50
Fax:
Isolation variations
mageba offers a comprehensive range of seismic isolation solutions.
Seismic isolation
A key method of seismic protection of structures is seismic isolation, whereby violent ground movements are isolated from the structure by suitably designed bearings. These seismic isolators support a structure’s superstructure in normal circumstances but isolate it from the destructive ground movements that might occur during an earthquake. The flexibility provided in the horizontal plane lowers the structure’s natural frequency, increasing its natural period and thereby reducing the accelerations to which it is subjected.
▷ Energy dissipation and re-centering
Seismic isolators generally also provide some degree of energy dissipation, which further reduces the destructive accelerations. Another important contribution of an effective seismic isolation system is the re-centering it can provide after an earthquake, avoiding residual displacements which would otherwise disrupt the structure’s serviceability.
Lead Rubber Bearings
A particularly effective, efficient and user-friendly type of seismic isolator is the Lead Rubber Bearing (LRB) – a relatively simple solution which combines the key isolation, energy dissipation and re-centering functions in a single compact unit. LRBs are similar to standard reinforced elastomeric bearings with steel connection plates at top and bottom for connection to the superstructure and substructure, with one key difference: they also include a lead plug at the core, joining one connection plate to the other. This lead plug deforms plastically when subjected to large horizontal forces during an earthquake, dissipating energy through hysteretic damping and heat generation. Thanks also to its relatively small size and robustness, and easy inspection and maintenance, LRBs are the most widely used seismic isolation solution in the world.
Sky Building | Ecuador
View of part of the array of installed LASTO®LRB bearings that seismically isolate the upper part of the Sky Building from the parking structure at its base
Installation of a LASTO®LRB during construction of the Sky Building
A LASTO®LRB seismic isolator during independent seismic testing for the Sky Building
The Sky Building in the Ecuadorian city of Guayaquil, for instance, is a 15-floor building with four parking levels and eleven office floors. This building is seismically protected by 64 LASTO®LRBs, installed on top of the parking structure to support the main structure above, isolating the movements of one from the other. Three different types of LRB, with diameters of up to 850 mm (33.5 inches), were designed for vertical loads of up to 10,000 kN (2,250 kips) and seismic displacements of up to 300 mm (12 inches).
Curved Surface Sliders
An alternative seismic isolator solution, the RESTON®PENDULUM bearing (also known as a curved surface slider) is based on the functional principle of a pendulum. It allows a structure to become horizontally displaced (and at the same time, lifted) during an earthquake, with seismic energy being dissipated by friction. After the earthquake, the curvature of the sliding surface of the base causes the supported structure to return by gravity to its original position. A significant advantage of this type of isolator over elastomeric types is its fire resistance.
Muisne Hospital | Ecuador
The Muisne Hospital, protected by 65 RESTON®PENDULUM seismic isolators
Installation of a RESTON®PENDULUM seismic isolator – Muisne Hospital
Representation of a RESTON®PENDULUM seismic isolator as designed for Muisne Hospital
Muisne Hospital in Ecuador’s Esmeraldas province is built as part of the reconstruction of the town of Muisne following a destructive earthquake in April of 2016. 65 RESTON®PENDULUM isolators (of the type DUPLO, which features two primary curved sliding surfaces) have been installed in recent months. These are designed for vertical loads of 750 kN (168 kips) and seismic movements of +/- 400 mm (16 inches).
These is just part of mageba’s range of seismic isolation solutions, which in turn is just part of our range of seismic protection solutions – demonstrate that mageba is well equipped to provide an isolation innovation for any application.
Please feel free to contact us when you require a seismic isolation (or any other type of seismic protection) solution for your structure – we will be happy to assist you.
