The spherical bearings might be designed for the highest level of loads among all of the contemporary used bridge bearings. Their construction is simple, they feature high resistance against wearing, low failure frequency and relatively small size. The bearings might operate in very low temperature and are often chosen to be used in railway bridge structures (often together with application of vibration dampers).
The spherical bearings consist of two backing plates - concave (which is fixed) and convex which can freely rotate. Between these adjacent parts the sliding surface is formed by contact surface - PTFE and stainless steel plates. The bearing which allows for horizontal movements is furthermore equipped with a sliding surface consisting of PTFE sheet and stainless austenitic sheet. The possible movements might be reduced by using lateral guides with sliding materials (in guided bearings) or restraining ring (in fixed bearings).
The spherical bearings combines the following properties – transferring of the loads from the superstructure to the substructure (vertical and horizontal) and allowing for the linear and rotational movements.
The following types are distinguished:
|
|
Reactions |
Movements |
Rotations |
|||||
|---|---|---|---|---|---|---|---|---|
|
N (vertical force) |
Vx (horizontal force along axis “x”) |
Vy
(horizontal force along axis “y”) |
vx
(movement along axis “x”) |
vy
(movement along axis “y”) |
αy
(rotation around axis “x”) |
αy
(rotation around axis “y”) |
||
| fixed (LSS) | + | + | + | - | - | + | + | |
| guided sliding (LSJ) | + | + | - | - | + | + | + | |
| + | - | + | + | - | + | + | ||
| free sliding (LSW) | + | - | - | + | + | + | + | |
| Harmonized standard |
EN 1337-7:2004 |
| Indended use | in bridge structures or any other structure with comparable support conditions where requirements on individual bearings are critical |
| Maximal designed vertical load capacity |
100 000 kN |
| Maximal rotation capacity |
±0,03 rad |
| Construction material |
steel grade S355 |
| Sliding material |
PTFE |
| Corrosivity category |
C5 (EN ISO 12944-5:2019) |
| Operating temperature | from -35 °C to 48 °C |
If the bearing is designed for movements which exceed ±50 mm, it features additional movement capacity ±20 mm obliged by the standard. In order to accommodate the effects of elastic and rheological contraction which naturally happen in post-tensioned structures, it is recommended to apply presettings of sliding plates in order to prevent excessive movements in starting of operation. The pressetings might also be required if the actual temperature of the structure is other than nominal temperature resulting from EN 1991-5 (+ 8°C). However, in many cases, the movement due to the difference between actual and nominal temperature is that small that it is covered by additional movement capacity.
Accessories
Our bearings are equipped with nameplates which present the basic characteristics (i.e. trade name, allowable loads both vertical and horizontal, allowable movements and rotations as well as information about place of installation and the manufacturer).
Movable bearings are equipped with movements indicators. On client’s request, it is also possible to install the anti-dust skirts.
The bearings manufactured by B2 have the Certificate of Constancy of Performance no. 0754 – CPD – 13-0148 issued by Karlsruher Institut für Technologie. According to the regulations1, the bearings are CE-marked and have the Declaration of Performance issued, which are delivered to the customer at the latest with the delivery.
Our offers are tailored to the individual customer’s needs, therefore we do not follow any catalogue solutions. We focus on high quality and short production and delivery time.
We encourage to contact with us and send the inquiries by the following link: Contact.
Additional technical and legal information might be found at Knowledge base.
1 Regulation (EU) No 305/2011 of the European Parliament and of the Council of 9 March 2011 laying down harmonised conditions for the marketing of construction products and repealing Council Directive 89/106/EEC
