SEISMIC RESTRAINT

Elastomer seismic restraint are used with restraint teeth in concrete put on the side of the beam and they have the function to contrast the movement of the building if there is an unconnecting with the bearings after a seismic event. The presence of the armed rubber pillow softens the impulsive effect of the seismic actions and it allows to dissipate a part of the energy during the cycles of deformation of the elastomer.

The dispositive is made from a steel plate of support which has buttonholes for the connection to the structures through anchor bolts or expansion wedges. This solution allows a rapid and an easy substitution of the restraint in the maintenance operations. The armed rubber pillow is fixed on the steel plate support by a vulcanization process.

This kind of fix antiseismic mechanic system are used to connect the mobile parts of structures to the fixed headings. Such necessity is particularly felt in the realization of the bridges and viaducts systems of seismic protection because these restraints take the high vertical loads of seismic actions off the bearings.

This device is structured like a zip with cinematism with double pendulum that has the characteristic not to oppose to the movements between the structures produced by phenomena of inflexion of the beams and yielding.

The project and the realization of this device has been performed in conformity to the following normatives and instructions:

• D.M. Min. 04/05/90 General criteria and technical prescriptions for the planning, execution and testing of the road bridges;
• Construction bearings instruments. Instructions for the use (CNR 10018);
• Instructions for the calculation, the execution, the testing and the laying in work of the devices of tie and the coverjoints in the railway impalcatis (ISTRUCTION 44 e).

RonamSism Elastomer seismic restraint technical properties

Materials properties (Steel Plates S235JR UNI EN 10025 (Fe360))

Materials properties (Natural Rubber (UNI EN 1337-3))