COMPOSITE SLIDING BLOCK FOR FRICTIONAL-TYPE SEISMIC ISOLATORS AND SEISMIC ISOLATORS WITH SAID COMPOSITE SLIDING BLOCK

Abstract

A composite sliding block to be arranged between two supporting plates of a frictional-type seismic isolator, with one supporting plate connected to the superstructure to be isolated and the other to the foundations, comprising two contact components that externally are slidingly or articulatedly in contact with said supporting plates, depending on whether the isolator has one or two sliding surfaces, and internally are coupled to each other by means of a male projection of one component in a female recess of the other. An elastomeric seal occupies an empty space surrounding the projection within the recess and, on the external side of the contact component(s) slidingly in contact with the supporting plate(s), a sliding plate is accommodated in a corresponding niche having an elastomeric compression support at the bottom. Frictional pendulum-type isolators with one or two concave sliding surfaces include such a block.

Claims

1. 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.

2. The composite sliding block of claim 1, wherein the composite sliding block has a general cylindrical shape, with the vertical male coupling projection and the female coupling recess also being cylindrical, the sliding plate having a circular shape and the elastomeric seal having the shape of a ring.

3. The composite sliding block of claim 1, wherein the female coupling recess has a bottom and side walls and a non-adhering sheet is arranged on said bottom of the female coupling recess to prevent the contact components from adhering to each other.

4. The composite sliding block of claim 1, wherein the material of the contact components is steel.

5. The composite sliding block of claim 1, wherein the elastomeric compression supports and the elastomeric seals are made of natural rubber.

6. The composite sliding block of claim 3, wherein the material of the non-adhering sheet is chosen from a metal or non-metal appropriate for a friction coefficient of between 0.20 and 0.50, and resistance to abrasion.

7. The composite sliding block of claim 1, wherein the sliding plates are made of a polymeric material, such as polytetrafluoroethylene (PTFE) or ultra-high molecular weight polyethylene (UHMWPE).

8. A friction pendulum-type seismic isolator with double concave sliding surfaces that is mounted between a superstructure and a substructure or foundations, wherein the seismic isolator comprises: a first support plate with an upper side joined to the superstructure and a lower side provided with one of the concave sliding surfaces; and a second support plate with a lower side joined to the substructure or the foundations and an upper side provided with the other of the concave sliding surfaces, wherein the friction pendulum-type seismic isolator further comprises a composite sliding block according to claim 1, located between the first plate and the second plate and in sliding contact with the concave sliding surfaces of both support plates.

9. The seismic isolator of claim 8, wherein the sliding plates of the composite sliding block have outer faces that have a spherical convex shape.

10. The seismic isolator of claim 8, wherein the concave sliding surfaces of the support plates are elliptical.

11. The seismic isolator of claim 8, wherein the support plates have containment flanges located on the periphery of the sliding surfaces.

12. A friction pendulum-type seismic isolator with a single concave sliding surface, mounted between a superstructure and a substructure or foundations, wherein the seismic isolator comprises: a first support plate connected to one between the superstructure and the substructure or the foundations, in which the support plate has at least one central portion with a concave spherical surface; and a second support plate with one side joined to the other between the superstructure and the substructure or the foundations, and an opposite side provided with said single concave sliding surface, wherein the friction pendulum-type seismic isolator further comprises a composite sliding block according to claim 1 located between the first support plate and the second support plate, wherein one of the contact components comprises, on its external side, a spherical cap for articulated contact with said at least one central portion with a concave spherical surface of the first support plate and wherein the other contact component is in sliding contact with the concave sliding surface of the second support plate.

13. The seismic isolator of claim 12, wherein the first support plate is made up of a flat connecting plate that is joined to one between the superstructure and the substructure or the foundations and a protruding intermediate plate joined to the flat connecting plate, wherein the protruding intermediate plate has an end provided with said at least one central portion with a concave spherical surface of the support plate.

14. The seismic isolator of claim 13, wherein the flat connecting plate and the protruding intermediate plate are manufactured as a single piece.

15. The seismic isolator of claim 12, wherein the first support plate has said at least one central portion with a concave spherical surface formed in a recess of the first support plate itself.

Description

DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1 shows the simple-curvature friction pendulum according to the prior art.

[0037] FIG. 2 shows the double-curvature friction pendulum according to the prior art.

[0038] FIG. 3 shows the double-curvature friction pendulum with internal ball joint according to the prior art.

[0039] FIG. 4 shows the Triple Friction Pendulum Bearing (TFPB) according to the prior art.

[0040] FIG. 5 represents an elevation view of a preferred embodiment of the invention constituted by a composite sliding block for a double sliding surface friction-type seismic isolator, in which the composite sliding block is disposed in an unloaded condition, that is to say, before the seismic isolator is mounted between a superstructure and a substructure or foundations.

[0041] FIG. 6 is a cross-sectional view along the vertical plane of symmetry of the composite sliding block of FIG. 5.

[0042] FIG. 7 represents a cross-sectional view along the vertical plane of symmetry a seismic isolator of double sliding surface, both of them concave, with the composite sliding block of FIGS. 5 and 6.

[0043] FIG. 8 is a plan view of the whole seismic isolator of FIG. 7 showing in broken lines the outline of the sliding surfaces of the support plates and the outline of the composite sliding block.

[0044] FIG. 9 is equivalent to FIG. 7 when the seismic isolator is in a centered position under a vertical load W.

[0045] FIG. 10 shows in detail the composite sliding block of the invention in a cross-sectional view along its vertical plane of symmetry, in the situation that the seismic isolator of FIG. 9 is in.

[0046] FIG. 11 is equivalent to FIG. 9 when the seismic isolator is in a displaced position due to being further subjected to a horizontal load Q, prior to the condition in which it impacts against the containment flanges.

[0047] FIG. 12 shows in detail the composite sliding block of the invention in a cross-sectional view along its vertical plane of symmetry, in the situation in which the seismic isolator of FIG. 11 is in.

[0048] FIG. 13 is equivalent to FIG. 11 when the seismic isolator has reached the impact position against the containment flanges located on the periphery of the sliding surfaces, in which the high friction interface is activated.

[0049] FIG. 14 shows in detail the composite sliding block of the invention in a cross-sectional view along its vertical plane of symmetry, in the situation in which the seismic isolator of FIG. 13 is in.

[0050] FIG. 15 is equivalent to FIG. 7 when the seismic isolator is in a displaced position due to being subjected to a horizontal load Q and, in addition, subjected to a vertical upwards load U, which produces a lifting of the support plate that is located on top of the composite sliding block.

[0051] FIG. 16 represents a cross-sectional view along the vertical plane of symmetry of a friction-type seismic isolator with only one sliding surface, the composite sliding block of the invention being adapted to this other type of seismic isolator, wherein the seismic isolator is disposed in a centered position and subjected to a vertical load W.

[0052] The invention is described in detail below, relating it to the figures.

DETAILED DESCRIPTION OF THE INVENTION

[0053] According to the preferred embodiment of the invention illustrated in FIGS. 5 and 6, the composite sliding block (1) conveniently has a general cylindrical shape and is made up of two contact components arranged one above the other, which we will herein refer to as the upper contact component (2) and lower contact component (3).

[0054] The composite sliding block is configured in this case for use in a double sliding surface friction-type seismic isolator, whereby the contact components have sliding plates of polymeric material (4) on their external side for respective sliding contact with the sliding surfaces of the support plates of the seismic isolator. The polymeric plates (4) have a circular shape and are close-fittingly accommodated in a respective cylindrical niche (5) machined on the corresponding external side of the contact component. The contact surfaces of the polymeric plates with the sliding surfaces of the isolator are flat and can also be convex spherical for a better adjustment to said sliding surfaces. In addition, each polymeric plate (4) rests on an elastomeric compression support (6) in the form of a ring that is centered within each niche.

[0055] On the other hand, the contact components (2, 3) are omnidirectionally slidingly coupled to each other through their facing internal sides, by means of a vertical cylindrical male coupling projection (7) of the upper contact component (2) inserted in a corresponding female coupling recess (8) of the lower contact component (3) that has the same shape but is of larger cross-sectional area.

[0056] At the contact interface between the male coupling projection (7) and the female coupling recess (8) the surfaces are both flat and horizontal, the female coupling recess having a bottom and side walls so that in said bottom there is arranged a sheet of thin non-adhering material (not distinguishable in the figures), to prevent these surfaces from adhering. In addition, the empty space surrounding the male coupling projection that is generated at the coupling between both contact components allows to insert a ring-shaped elastomeric seal (9) that prevents metal-to-metal impact when relative lateral displacement occurs between the upper contact component (2) and the lower contact component (3).

[0057] In the following figures (FIGS. 7, 8, 9, 11, 13 and 15) the composite sliding block of FIGS. 5 and 6 is illustrated, specifically being mounted on a friction-type seismic isolator (10) with double concave sliding surface (13), wherein the following elements are distinguished:

[0058] an upper support plate (11) having an upper side joined by bolts to a superstructure (not shown) and a lower side provided with one of the concave sliding surfaces of the seismic isolator;

[0059] a lower support plate (12) having a lower side joined by bolts to the substructure or foundations (not shown) and an upper side provided with the other of the concave sliding surfaces (15) of the seismic isolator; and

[0060] the composite sliding block (1) located between the upper support plate (11) and the lower support plate (12) and in sliding contact with the respective concave sliding surfaces (13).

[0061] As can be seen in FIGS. 9 and 10, when the structure is subjected to a vertical load W, the elastomeric compression supports deform until they occupy all the empty spaces of the niches, thus remaining completely confined between the polymeric plate and the lateral walls and bottom of the niches. In this way, it acts as an element that absorbs the impact in the vertical direction, dissipating energy due to deformation of the elastomeric compression support.

[0062] In FIGS. 11 and 12 the structure is shown in a displaced position, subjected to a vertical load W and a lateral load Q, prior to the impact condition of the composite sliding block (1) against the containment flanges (14) of the periphery of the concave sliding surfaces (13), in a situation in which the high friction interface is said to be inactive.

[0063] FIGS. 13 and 14 represent the condition of lateral impact of the composite sliding block (1) against the containment flanges (14), wherein forces are generated that induce the relative sliding of the upper and lower contact components at the high-friction interface or, in other words, wherein the high-friction interface is active. Under these conditions, the elastomeric seal (9) is laterally compressed, acting as a restorative element and preventing the metal-to-metal impact of the two contact components of the composite sliding block. In this way, the composite sliding block of the invention acts as a system that absorbs the impact in the lateral direction, dissipating energy by friction in the high-friction interface, and by lateral deformation of the elastomeric seal.

[0064] FIG. 15 represents the lifting condition produced by an upward vertical load U caused by the independent or simultaneous action of the overturning moment and vertical acceleration of the ground. Note that the top support plate (11) loses contact with the composite sliding block (1), allowing the elastomeric compression supports to return to their original shape shown in FIG. 8. When the upper support plate (11) returns to rest on the composite sliding block (1), a condition that we call vertical impact, the elastomeric compression supports are compressed again occupying all the empty spaces of the niches, thus allowing to dampen the effect of the impact.

[0065] Finally, FIG. 16 shows an application of the same composite sliding block of the invention but arranged in a friction-type isolator with a single sliding surface, similar to the one shown in FIG. 1 (prior art). The isolator is shown in its centered position and subjected to a vertical load W. Note that the external side of one of the contact components of the composite sliding block, in this case the contact component located above, is formed by a spherical cap (15) that acts as a low friction joint in rotary contact with at least one central portion with a concave spherical surface, of the upper support plate. More specifically, the upper support plate is comprised of a flat connection plate (17) joined on one side to the superstructure and joined on the other side to a protruding intermediate plate (16), wherein the end of the protruding intermediate plate is provided with said at least one central portion with a spherical concave surface. Clearly, instead of the upper contact component it could be the lower contact component that comprises the spherical cap and is in articulated low-friction contact with the lower support plate and it could be the lower support plate that comprises a flat connecting plate and a protruding intermediate plate with a central portion with a concave spherical surface in rotary contact with said spherical cap.

[0066] All the elements (the spherical cap and plates) are preferably made of metal, more preferably carbon steel, and the flat connecting plate and intermediate plate are preferably joined by welding.