Composite sliding block for frictional-type seismic isolators and seismic isolators with said composite sliding block

A composite sliding block for friction-type seismic isolators with one or two sliding surfaces which are mounted between a superstructure and a substructure or foundations and are comprised of two support plates connected, one of them to the superstructure and the other one to the substructure or the foundations, wherein, if the seismic isolator has two sliding surfaces, the composite sliding block is arranged between the two support plates and slidingly in contact with both support plates and, if the seismic isolator has only one sliding surface, the composite sliding block is arranged slidingly in contact with one of the support plates and articulatedly in contact with a concave spherical surface of the other support plate, wherein the composite sliding block is formed by two contact components disposed one on top of the other, having the contact components an external side and internal sides facing each other,

• wherein through said external sides the sliding block exerts said sliding or articulated contact with the support plates and through said facing internal sides the contact components are omnidirectionally slidingly coupled to each other by means of vertical male coupling projection of one of the contact components in a shape-matching but larger cross-sectional area female coupling recess of the other contact component,
• whereby there is an empty space surrounding the vertical male coupling projection within the female coupling recess which is occupied by an elastomeric seal capable of being laterally compressed by the effect of the relative displacement between the two contact components when the seismic isolator is subject to a lateral load, wherein the composite sliding block further comprises a sliding plate on the external side of the contact component or components which are respectively in sliding contact with one or both support plates, wherein the support plate is accommodated in a corresponding niche on said external side of the contact component, wherein the niche has a bottom and side walls and
• wherein in between the sliding plate and the bottom of the niche there is disposed, confined, an elastomeric compression support that is deformable with a vertical load over the seismic isolator.