Seismic isolations - Import export

The behavior of the LDRB isolators is highly linear in shear stiffness and the damping ratio is 2 - 3% of critical damping. There is no creep in the material and the stability of the modulus of elasticity is very good. Advantages of LRDB insulators; they can be modulated in a simpleway and they are less affected by the factors that have mechanical behaviors. These insulators may need additional damping elements.

Curved surface sliders use gravity as a recentering force; the operating principle is the same as the pendulum. Energy dissipation is ensured by the friction of the main sliding surface. The parameters for the bilinear constitutive bond depend on the bending radius and friction coefficient. They are divided into two types, the FIP and FIP-D series, respectively with one or 2 primary sliding surfaces that allow for horizontal displacement. In the case of very wide displacements we recommend to use double curved sliding isolators (FIP-D), which permit to reduce plan dimensions. Experimental hysteretic cycles of a FIP isolator. A FIP-D isolator during testing at the SRMD laboratory of the University of California in San DIEGO. A FIP-D isolator installed in the building "Le Betulle" of Castel di Sangro (AQ).

These isolators are the combination of a bearing and dampers in a single device; the latter are typically hysteretic dampers of steel and/or fluid viscous dampers. As such, they are characterized by a high damping capacity. The bearing can be multidirectional or unidirectional. Isolators can also include shock transmitters or mechanical fuse restraints. Experimental hysteretic cycles of a flat sliding isolator with steel hysteretic dampers. Installation of a flat sliding isolator with steel hysteretic dampers, at the Santuario 'Madonna delle Lacrime' of Siracusa. Flat sliding isolators with steel hysteretic dampers, installed in the railway lines "Caracas-Cua" and "La Encrucijada-Puerto Cabello", Venezuela.

LRB isolators are elastomeric isolators with a cylindrical-shaped core of lead. The plasticization of lead permits to obtain an equivalent viscous damping coefficient up to approximately 30%. The constitutive bond of LRB isolators is bilinear; for design purposes it is possible to use equivalent non-linear or linear models, according to regulatory provisions. Experimental hysteretic cycles of an LRB isolator at a 0.5 Hz frequency and cutting deformation ± 100%. Vibrating table tests on an LRB isolator at the National Technical University of Athens (Greece). LRB isolators installed in the office building "La Torre" of Ancona.

The SI-series elastomeric isolators consist of alternate layers of steel and elastomer connected by curing. Their behaviour can be modelled as linear, based on equivalent stiffness and the equivalent viscous damping coefficient. Usually they are made of high-damping elastomeric mixtures, i.e. with equivalent viscous damping coefficient between 10 and 15% and shear deformation of 100% Experimental hysteretic cycles of a SI isolator at a 0.5 Hz frequency and shear deformation ± 100% Preparation, at FIP INDUSTRIALE laboratory, of an experimental test on two SI isolators of diameter 1150 mm. A SI isolator installed at the "Da Luz" hospital of Lisbon (Portugal).

These isolators are similar to the previous but with the exception that the dissipation of energy is obtained also through the use of one or more lead cores. Lead (used here at a level of gg.go% purity) has the property of undergoing plastic deformation as it dissipate energy and then re-crystallizing after a cycle of plastic deformation. Because of this, it is able to sustain an unlimited number of hysteresis loops.

The bearings we have defined so far are the basic types, which constant feature is the fact that they allow all-ways movements and rotation. However, movements can be limited in one or all ways, thus obtaining guided or fixed bearings, respectively. In the first case -guided bearings- the restriction is obtained by means of guides parallel to the supporting axe that allows movement. To make friction as low as possible, PTFE and stainless steel sheets are welded to the guides.

They are divided into two categories: ELASTOMERIC Elastomeric isolators SI Elastomeric isolators with lead core LRB SLIDING Curved surface sliders FIP, FIP-D Flat surface sliders with dampersi VEL, VEP, VOP, VOTP, VELOP, VELOTP

They protect buildings, bridges, flyovers, or any other facility, changing their reaction to the seismic action or other dynamic actions (for example wind). Most seismic devices are used within the innovative approach to seismic engineering, to change the seismic reaction of a structure by seismic isolation and/or energy dissipation. Namely: • ISOLATORS: they limit the acceleration transferred to the structure and reduce inertial stress by increasing the oscillation period. • DAMPERS: they dissipate part of the energy transferred to the structure according to their constitution, based on which they are divided into two large families, speed-dependent devices and displacement-dependent devices. On the other hand, FIXED RESTRAINT DEVICES are traditionally used in the traditional approach to seismic engineering, to transfer horizontal stress. TYPES: Seismic isolators Speed-dependent devices Displacement-dependent devices Fixed restraint devices

Within the conservation of the world artistic heritage, it is always present the necessity of protecting the works of inestimable value from seismic movements, not only by means of seismic protection techniques of the building where the artistic works are, but also through the direct seismic isolation of the works themselves. FIP INDUSTRIALE has studied and developed a chain of innovative products for seismic isolation called ISOLART, aimed to the protection of works of art from the effects of seismic movements, through the decoupling between the movement of the work of art and the movement of the building which contains it, induced by the earthquake. These products are subdivided into ISOLART ® PENDULUM which is based on the idea of the pendulum, ISOLART ® FLUID and ISOLART ® SMA which is based on the characteristics of the shape memory alloy.

Series NE elastic devices (buffers) are anti-lifting axial devices consisting of a set of elastomeric disc inserted between steel plates. A set of bars connects the plates to the anchoring ends and allows the discs to operate under compression, despite the displacement direction. Elastic devices are traditionally used in bridges next to an abutment and/or between adjacent decks, over the joints. Experimental force-displacement curve of an elastic device. NE devices installed along the "Conexion Rosario-Victoria", in Argentina. NE devices installed in the Somplago flyover, the first seismically isolated European bridge (1974-1976).