WO2020053756A1 - Pot bearing for constructions - Google Patents
Pot bearing for constructions Download PDFInfo
- Publication number
- WO2020053756A1 WO2020053756A1 PCT/IB2019/057615 IB2019057615W WO2020053756A1 WO 2020053756 A1 WO2020053756 A1 WO 2020053756A1 IB 2019057615 W IB2019057615 W IB 2019057615W WO 2020053756 A1 WO2020053756 A1 WO 2020053756A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- pot
- elastomeric pad
- bearing according
- seal
- pot bearing
- Prior art date
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
- E01D19/00—Structural or constructional details of bridges
- E01D19/04—Bearings; Hinges
- E01D19/042—Mechanical bearings
- E01D19/047—Pot bearings
Definitions
- the present invention concerns in general the sector of structural supports for building constructions, and in particular a pot bearing that allows rotation between two elements of a construction.
- structural supports are generally used that define between two or more parts of the structure slider or hinge constraints, as well as combinations thereof.
- the bearings have the function of allowing relative movements between the parts of the structure, typically translations and/or rotations, both in exceptional conditions, such as in the case of seismic events, and in normal operating conditions in which such relative movements occur as a result of the weight of the construction, viscous deformations and shrinkage of building materials, thermal actions, as well as actions related to wind and normal use of the construction, such as the effects of traffic in the case of bridges and viaducts.
- Structural bearings for buildings are codified in technical standards that form the state of the art, such as the European standard EN 1337 “Structural Bearings” or the American standard AASHTO LRFD “Bridge Design Specifications” (8th edition, 2017).
- Pot bearings consist of a base plate, also called a “pot”, an elastomeric pad, generally in the shape of a disc, accomodated in the base plate, and a top plate, also called a “piston”, which protrudes at least partially inside the base plate and rests on the elastomeric pad.
- a base plate also called a “pot”
- an elastomeric pad generally in the shape of a disc, accomodated in the base plate
- a top plate also called a “piston” which protrudes at least partially inside the base plate and rests on the elastomeric pad.
- Both the base plate and the top plate are typically made of metal alloys, for example steel.
- the base plate is normally connected to the substructure (abutment or pillar) and the top plate to the superstructure (deck), although the pot bearings can be used in reverse configuration.
- the pot bearing allows the superstructure to rotate relative to the substructure by deforming the elastomeric pad.
- the elastomer accomodated inside the pot is confined in every direction and, under the high pressures to which it is subjected as a result of the vertical load transmitted by the top plate, it deforms, acting as an incompressible fluid, thus allowing the relative rotation between the pot and the top plate around a generic horizontal axis.
- an internal seal is fundamental, which circumferentially surrounds the rim of the elastomeric disc and prevents the escape of elastomeric material through the clearance between the walls of the pot and the piston, especially in the presence of high stresses due to the vertical loads coming from the superstructure.
- Pot bearings are generally fitted with an additional external seal, located between the top plate and the top of the base plate, in order to prevent moisture and debris from entering the gap between the two elements.
- the internal seal is typically inserted between the rim of the elastomeric pad and the wall of the internal cavity of the base plate, usually in an annular- shaped seat formed at the rim of the elastomeric pad, or it can be formed as an integral part of the elastomeric pad during the vulcanization process.
- the internal seal can be manufactured in one of the following materials: stainless steel, brass, polyoxymethylene (POM), and polytetrafluoroethylene (PTFE) filled with 25% carbon by weight.
- the polytetrafluoroethylene seal is made from a semi-finished band- shaped product that is calendered around the circumference of the elastomeric pad, and joining the ends of the band, as described in Figure A.l of the above standard.
- UHMWPE ultra- high molecular weight polyethylene
- POM polyoxymethylene
- MFI 190/2.16 melt flow index
- the characteristics of the internal seal are of fundamental importance for defining the performance and durability of the elastomeric disc bearing.
- the internal seal prevents the elastomeric material from rising through the clearance between the pot and the piston, it determines the maximum pressure (i.e. the maximum vertical force per unit area) applicable to the pad of elastomeric material.
- the maximum pressure applicable to the elastomeric pad is 60 MPa.
- This value depends, in addition to the properties of the internal seal, also on the size of the clearance between the pot and the piston, which according to the technical standard EN 1337-5:2005 must not exceed 0,8 mm when using a PTFE seal with carbon and 1,0 mm for other types of seal.
- the oscillations of the angle of rotation produced by the variable loads due for example to the passage of vehicles or trains on a bridge or viaduct, produce a sliding of the internal seal on the wall of the internal cavity of the pot, which determines the life of the seal itself.
- the total distance travelled by the internal seal while maintaining its functionality also referred to in standard EN 1337-5:2005 as the "accumulated slide path" is one of the criteria used to define the useful life of the elastomeric disc bearing.
- the standard EN 1337-5:2005 defines different values of the accumulated slide path according to the type of internal seal, namely 500 m for stainless steel seals, 1000 m for brass seals and 2000 m for POM and carbon-filled PTFE seals.
- the accumulated slide path is checked experimentally through a test conducted according to the method described in Annex E of EN 1337-5:2005, and consists in subjecting a pot bearing to a sinusoidal rotation around a horizontal axis with a total amplitude equal to 0,005 radians, i.e. the maximum amplitude of rotation due to the frequent combination of variable loads prescribed by the standard, at a frequency between 0,25 and 2,5 Hz.
- the rotation frequency is a fundamental parameter for checking the accumulated slide path, since increasing the rotation frequency increases in proportion the sliding speed of the internal seal on the surface of the internal cavity of the pot, leading to an increase in friction and accelerating the wear of the seal itself.
- the total distance travelled by the internal seal during the service life of the elastomeric disc bearing depends on the amplitude of the rotations due to the variable loads, on the total number of rotations, but also on the dimensions of the elastomeric pad.
- both the displacement of the internal seal on the wall of the internal cavity of the pot and the speed at which this displacement occurs are proportional to the diameter of the elastomeric pad.
- increasing the diameter of the elastomeric disc results in a reduction in the total number of rotations that the pot bearing is able to undergo, keeping the other parameters constant, in particular the amplitude and frequency of rotation.
- Pot bearings have found wide application in road and rail bridges and viaducts thanks to their simplicity, compact size, economy and low maintenance requirements.
- the EN 1337-5:2005 standard recommends the use of pot bearings with internal seals in POM or PTFE with carbon.
- the continuous increase in both heavy and light traffic, and the advance of high-speed railway lines have introduced ever higher performance requirements, higher than those that conventional pot bearings can meet.
- the passage of high-speed trains produces rotational oscillations, at the supports, which occur in very short periods; for example, assuming a train speed between 300 and 350 km/h and a distance between the bogies of a carriage equal to 18,70 m, the frequency of oscillation of the support is between 4,45 and 5,20 Hz.
- This frequency which is twice as high as the maximum frequency at which the internal seal is checked according to EN 1337-5:2005, leads to a significant increase in the speed of wear of the seal itself, reducing disadvantageously the accumulated slide path compared to the value defined and verified according to the standard.
- the increase in the size of the elastomeric pad determines a proportional increase in the displacement of the seal during a single rotation, as well as in the speed with which this displacement occurs.
- EP 2784220 describes a pot bearing with internal POM seal in which the seal material is modified to have a flow index (MFI 190/2.16 according to EN ISO 1133) with a value lower than the range required by the standard.
- MFI 190/2.16 according to EN ISO 1133
- This allows to obtain an increase in the contact pressure of the elastomeric pad up to twice the value required by the standard, as well as an increase in the accumulated slide path up to 1,6 times the value required by the standard, but no further advantages are described in terms of increase in the sliding speed that can be withstood by the seals.
- spherical bearings of the type described in the EN 1337-7:2004 standard "Structural Bearings. Part 7: PTFE spherical and cylindrical bearings", in which the rotation of the bearing is achieved through the rotation of a spherical metal cap inside a concave metal base.
- PTFE polytetrafluoroethylene
- UHMWPE ultra- high molecular weight polyethylene
- the idea of a solution underlying this invention is to make the internal seal, preferably of the annular type, of the pot bearing starting from a semi-finished product, such as, for example, a band obtained by drawing, which consists entirely or at least mainly of PTFE modified with the addition of perfluoropropylvinylether (PPVE) in percentages between 0,1% and 0,3% in weight.
- a semi-finished product such as, for example, a band obtained by drawing, which consists entirely or at least mainly of PTFE modified with the addition of perfluoropropylvinylether (PPVE) in percentages between 0,1% and 0,3% in weight.
- PPVE perfluoropropylvinylether
- PPVE a PTFE modification agent for use in structural bearings
- PTFE modified with PPVE is used in the form of a sheet, obtained from a semi-finished product moulded by compression, and allows to obtain a lower coefficient of friction and a greater resistance to creep than pure PTFE at low temperatures and in particular at temperatures below -35°C and down to -50°C, allowing the application of sliding bearings for the construction sector beyond the limits imposed by current technical standards.
- PTFE modified with PPVE is instead used for the internal seal of an elastomeric disc bearing, obtained from a semi-finished product consisting of a band, preferably obtained by drawing.
- the inventor has in fact discovered that the addition of PPVE to PTFE allows the seal to withstand significantly higher sliding speeds than those tolerated by seals manufactured according to EN 1337- 5:2005, including those manufactured with PTFE without a modifying agent, at the same time presenting an advantageously lower wear.
- PPVE PPVE
- the addition of PPVE as a modifying agent increases the resistance of the internal seal, allowing it to withstand higher pressures on the elastomeric pad than the value defined and verified according to EN 1337-5:2005.
- the allowable increase in pressure on the elastomeric pad therefore makes it possible to make pot bearings, capable of withstanding high loads, more compact than those defined in EN 1337- 5:2005.
- the pot bearings according to the present invention thanks to the characteristics of increased durability of the internal seal even in the presence of high sliding speeds such as those produced by the passage of trains at high speed, and increased pressure applicable to the elastomeric pad provided by the new internal seal, allow the creation of bearings more compact, less bulky and heavy, and with reduced maintenance requirements, resulting in an advantageous reduction in costs, not only of the bearing but of the entire construction and of its maintenance.
- the pot bearing according to the present invention withstands sinusoidal rotations with a total amplitude of 0,005 radians at a frequency of at least 5 Hz, verified on an accumulated slide path of at least 2000 m according to the method described in Annex E of EN 1337-5:2005, equal to twice the maximum rotation frequency provided for in the standard.
- the internal seal of the pot bearing according to the present invention exceeds an accumulated slide path of at least 4000 m with a sliding speed of at least 15 mm/s, equal to twice the accumulated slide path foreseen in the standard for the technical class of carbon-filled PTFE seals.
- the pot bearing according to the present invention allows to apply to the elastomeric pad a contact pressure of at least 120 MPa, defined and verified according to the method described in Annex E of EN 1337-5:2005, equal to double the characteristic contact pressure of the elastomeric pad foreseen in the standard.
- the internal seal of the pot bearing according to the present invention can also be lubricated initially with a grease, preferably silicone grease, to reduce the coefficient of friction and increase wear resistance and durability.
- a grease preferably silicone grease
- the preferred type of silicone grease is methyl phenyl silicone oil thickened with lithium soap.
- the internal seal of the pot bearing according to the present invention is inserted between the rim of the elastomeric pad and the wall of the internal cavity of the pot, within a recess formed in the pad rim.
- the internal seal can be simply inserted into the recess by circumferentially surrounding the pad, or formed as an integral part of the elastomeric pad during the curing process, or even glued with an adhesive to the elastomeric pad.
- the joint between the two ends of the calendered band from which the seal is obrtained can be made not only according to the type described in Figure A.l of EN 1337-5:2005, but other embodiments of the joint are also possible.
- a further advantage of the material used to manufacture the internal seal of the elastomeric disc bearing is the fact that its characteristic properties are scarcely temperature dependent.
- the requirements defined in EN 1337-5:2005 are met at temperatures between -50°C and +70°C.
- the pot bearing according to the invention can also be used advantageously in extreme environmental conditions, in which the bearings described in EN l3375-:2005 cannot be used, their range of use being limited between -40°C and +50°C.
- the pot bearing according to the present invention can be advantageously coupled with a flat sliding element, as described in Part 2 of EN 1337 (EN 1337-2:2004 "Structural bearings. Part 2: sliding elements") or in EP 2784220 (Fig.4), in order to allow translation movements of the superstructure with respect to the substructure, for example movements due to thermal actions resulting from temperature variations or the effects of cable pre-tensioning.
- One or more sliding guides may be coupled to the flat sliding element, as described in EN 1337-2:2004, to allow the translation movement in one horizontal direction only.
- the elastomeric pad as an alternative to the disc shape, can have an oval or an annular shape as shown, respectively, in figures 5-7 and figures 8-9 of the above- mentioned EP 2784220. In the latter case, of course, there will be two internal seals to achieve the sealing also in correspondence of the central tubular structure of the pot.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Bridges Or Land Bridges (AREA)
- Sliding-Contact Bearings (AREA)
- Fertilizers (AREA)
Abstract
Description
Claims
Priority Applications (8)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PL19783122.5T PL3850157T3 (en) | 2018-09-11 | 2019-09-10 | Pot bearing for constructions |
AU2019340588A AU2019340588A1 (en) | 2018-09-11 | 2019-09-10 | Pot bearing for constructions |
ES19783122T ES2923591T3 (en) | 2018-09-11 | 2019-09-10 | Encapsulated bearing for constructions |
HRP20220947TT HRP20220947T1 (en) | 2018-09-11 | 2019-09-10 | Pot bearing for constructions |
SG11202102307XA SG11202102307XA (en) | 2018-09-11 | 2019-09-10 | Pot bearing for constructions |
RS20220754A RS63472B1 (en) | 2018-09-11 | 2019-09-10 | Pot bearing for constructions |
EP19783122.5A EP3850157B1 (en) | 2018-09-11 | 2019-09-10 | Pot bearing for constructions |
SI201930289T SI3850157T1 (en) | 2018-09-11 | 2019-09-10 | Pot bearing for constructions |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IT201800008504 | 2018-09-11 | ||
IT102018000008504 | 2018-09-11 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2020053756A1 true WO2020053756A1 (en) | 2020-03-19 |
Family
ID=64427061
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/IB2019/057615 WO2020053756A1 (en) | 2018-09-11 | 2019-09-10 | Pot bearing for constructions |
Country Status (11)
Country | Link |
---|---|
EP (1) | EP3850157B1 (en) |
AU (1) | AU2019340588A1 (en) |
ES (1) | ES2923591T3 (en) |
HR (1) | HRP20220947T1 (en) |
HU (1) | HUE059336T2 (en) |
PL (1) | PL3850157T3 (en) |
PT (1) | PT3850157T (en) |
RS (1) | RS63472B1 (en) |
SG (1) | SG11202102307XA (en) |
SI (1) | SI3850157T1 (en) |
WO (1) | WO2020053756A1 (en) |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2784220A1 (en) * | 2013-03-28 | 2014-10-01 | Mageba S.A. | Pot bearing |
WO2015136457A1 (en) * | 2014-03-11 | 2015-09-17 | Cave S.R.L. | Sliding bearing for constructions |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ATE83518T1 (en) | 1988-03-21 | 1993-01-15 | Schwaebische Huettenwerke Gmbh | TOP STORAGE FOR STRUCTURES, PARTICULARLY BRIDGE STRUCTURES. |
WO2006042566A1 (en) | 2004-10-19 | 2006-04-27 | Maurer Söhne Gmbh & Co. Kg | Bearing and use of uhmwpe in bearings in civil engineering |
-
2019
- 2019-09-10 HR HRP20220947TT patent/HRP20220947T1/en unknown
- 2019-09-10 ES ES19783122T patent/ES2923591T3/en active Active
- 2019-09-10 WO PCT/IB2019/057615 patent/WO2020053756A1/en unknown
- 2019-09-10 PL PL19783122.5T patent/PL3850157T3/en unknown
- 2019-09-10 AU AU2019340588A patent/AU2019340588A1/en active Pending
- 2019-09-10 EP EP19783122.5A patent/EP3850157B1/en active Active
- 2019-09-10 SI SI201930289T patent/SI3850157T1/en unknown
- 2019-09-10 HU HUE19783122A patent/HUE059336T2/en unknown
- 2019-09-10 RS RS20220754A patent/RS63472B1/en unknown
- 2019-09-10 SG SG11202102307XA patent/SG11202102307XA/en unknown
- 2019-09-10 PT PT197831225T patent/PT3850157T/en unknown
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2784220A1 (en) * | 2013-03-28 | 2014-10-01 | Mageba S.A. | Pot bearing |
WO2015136457A1 (en) * | 2014-03-11 | 2015-09-17 | Cave S.R.L. | Sliding bearing for constructions |
Also Published As
Publication number | Publication date |
---|---|
AU2019340588A1 (en) | 2021-04-01 |
SI3850157T1 (en) | 2022-09-30 |
HUE059336T2 (en) | 2022-11-28 |
EP3850157A1 (en) | 2021-07-21 |
HRP20220947T1 (en) | 2022-10-28 |
PL3850157T3 (en) | 2022-09-26 |
RS63472B1 (en) | 2022-08-31 |
SG11202102307XA (en) | 2021-04-29 |
EP3850157B1 (en) | 2022-05-18 |
PT3850157T (en) | 2022-07-26 |
ES2923591T3 (en) | 2022-09-28 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP3117050B1 (en) | Sliding bearing for constructions | |
KR101256829B1 (en) | Spherical bearing and plastic block with spherical surface for the same | |
CN101208548B (en) | Dynamic seal, rotary seal and method of making high temperature dynamic seal | |
US9540780B2 (en) | Pot bearing | |
CA2266549C (en) | Improved polymer reinforced fluid seal | |
EP3850157B1 (en) | Pot bearing for constructions | |
JP7241227B1 (en) | spherical sliding bearing | |
KR101708886B1 (en) | Engineering plastic friction member, isolator and method for making the same | |
US7904993B2 (en) | Spherical bearing for lock gate door and lock gate door having the same | |
WO2021057875A1 (en) | Spherical steel support | |
US4928339A (en) | Pot-type bearing for constructions such as bridges or the like | |
CN101338818B (en) | Film bearing seal device | |
US20160333926A1 (en) | Plain bearing and/or systems incorporating such bearings | |
CN107905094A (en) | A kind of adaptive bridge pad | |
CN106837987B (en) | Sliding bearing rotation connecting part | |
ITMI20071422A1 (en) | LOW-FRICTION STRIPED BEARING AND HIGH LOAD CAPACITY FOR STRUCTURAL ENGINEERING AND THE SAME MATERIALS | |
EP4290011A1 (en) | Sliding discoidal element for a structural support assembly in civil engineering and structural mechanism | |
CN219621588U (en) | Vibration reduction type friction pendulum support | |
CN216279343U (en) | Water turbine self-compensating type sealing ring with dissimilar material composite structure for main shaft sealing | |
US11746925B2 (en) | Valve packing ring set | |
RU2132499C1 (en) | Combined circular seal | |
SU1682700A1 (en) | Detachable joint seal | |
JPS63501440A (en) | Sealing device and sealing method | |
WO2022101816A1 (en) | Antifriction structural bearing | |
RU23942U1 (en) | SAFETY VALVE |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 19783122 Country of ref document: EP Kind code of ref document: A1 |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
ENP | Entry into the national phase |
Ref document number: 2019340588 Country of ref document: AU Date of ref document: 20190910 Kind code of ref document: A |
|
ENP | Entry into the national phase |
Ref document number: 2019783122 Country of ref document: EP Effective date: 20210412 |