Sliding bearing for supporting civil or structural engineering works
A sliding bearing, arranged for supporting civil or structural engineering works, such as for example bridges or buildings, seismically isolated or not, where the bearing comprises A) a base ( 3 ) and an upper support ( 5 ); B) a sliding element ( 7, 7 ′) interposed between the base ( 3 ) and the upper support, and against which the base ( 3 ) and the upper support rest. The sliding element ( 7, 7 ′) comprises at least one layer ( 11, 11′, 11″, 11 III ) made of a sliding material ( 9 ) comprising in turn B.1) a content by weight equal to or greater than 50% wt of one or more fluorinated polymers; B.2 a content by weight comprised between 1-20% wt of boron nitride in hexagonal form. The mechanical properties of the sliding material ( 9 ) for use as a structural bearing or an anti-seismic isolator, are less sensitive to a temperature and environmental humidity with respect to known sliding materials.
1. A sliding bearing arranged for supporting a civil or structural engineering work, the hearing comprising:
a base and an upper support;
a sliding element interposed between the base and the upper support, and against which the base and the upper support rest;
and wherein the sliding element comprises at least one layer made of a sliding material comprising:
a content by weight equal to or greater than 50% wt of one or more fluorinated polymers;
a content by weight comprised between 1-20% wt of boron nitride in hexagonal form.
2. The bearing according to claim 1 , wherein the sliding material has a content by weight equal to or greater than 50% wt of polytetrafluoroethylene.
3. The bearing according to claim 1 , wherein the sliding material has a content by weight comprised between 1-20% of carbon fibres.
4. The bearing according to claim 1 , wherein the sliding material has a content by weight comprised between 1-20% of wollastonite fibres.
5. The bearing according to claim 1 , wherein the sliding material has a content by weight comprised between 1-15% wt of boron nitride.
6. The bearing according to claim 1 , wherein the sliding material has a content by weight comprised between 1-10% wt of boron nitride in hexagonal form.
7. The bearing according to claim 1 , wherein the sliding material has a content by weight comprised between 2-5% wt or between 6-10% wt of boron nitride in hexagonal form.
8. The bearing according to claim 1 , wherein the sliding material has a content by weight comprised between 2-7% of carbon fibres and/or wollastonite fibres.
9. The bearing according to claim 1 , wherein the sliding material at 70° C. has a compressive strength of at least 120 MPa.
10. The bearing according to claim 1 , wherein:
the base forms a first sliding surface;
the upper support forms a second sliding surface;
the sliding element interposed between the first sliding surface and the second sliding surface, and rests against them;
at least one of the first sliding surface and the second sliding surface has a substantially flat shape.
11. The bearing according to claim 1 , wherein:
the base forms a first sliding surface;
the upper support forms a second sliding surface;
the sliding element is interposed between the first sliding surface and the second sliding surface, and rests against them;
at least one of the first sliding surface and the second sliding surface has a concave shape.
12. The bearing according to claim 11 , wherein:
the sliding element forms two larger faces forming respectively a third sliding surface and a fourth sliding surface;
the first sliding surface rests against the third sliding surface;
the second sliding surface rests against the fourth sliding surface;
at least one of the third has a convex shape.
13. The bearing according to claim 12 , wherein at least one of the third and the fourth sliding surface are obtained from a layer made of the sliding material.
14. The bearing according to claim 1 , wherein:
the base or the upper support forms a first sliding surface;
the sliding element is interposed between the base and the upper support and forms a second sliding surface;
at least one of the first and the second sliding surface has a substantially flat shape.
15. The bearing according to claim 1 , wherein:
the base forms a first sliding surface;
the sliding element is interposed between the base and the upper support and forms a second sliding surface;
at least one of the first and the second sliding surface has a substantially concave or convex shape, and forms a portion of a spherical surface.
16. The bearing according to claim 1 , wherein the bearing is a seismic isolator.
17. The bearing according to claim 1 , wherein the civil or structural engineering work is a bridge, building, silo, tank, crane, nuclear reactor, or a component thereof.