Products
Spherical Bearing

1. Principle

GTS Spherical bearings are used to transfer all loads from superstructure to substructure, and also facilitate movements in every direction and rotations about every axis. They do not contain any elastomeric parts and rotations take place on a spherical surface, including a PTFE sliding surface and a chromium plate surface (or SS surface in some cases).

GTS Spherical bearings can be fabricated and designed in accordance with EN1337-7, BS5400 or AASHTO LRFD bridge construction specifications, as appropriate.


2. Structures

w Base plate/concave plate: A concave spherical surface with a recess to confine the spherical PTFE sheet.

w Convex plate: A hard chromium plate, which consists of chromium spherical surface to contact with spherical PTFE sheet to facilitate rotation of bearing and a flat recess to confine the flat PTFE sheet.

w Sliding mating surface (typically PTFE&SS plate): Consists of a dimpled PTFE sheet and a stainless steel plate which remains flat and in full contact with top plate and completely covers the PTFE sheet under maximum displacement. The friction coefficient of these two parts remains at a low level, less than 0.03.

w Top plate: It helps to keep the flatness of SS and plays a supporting role.


3. Application and Advantage

GTS Spherical bearings can be widely applied in engineering and have the following superior performance:

w Transferring very large vertical load, it is possible to cover a wide range from 1000kN to 80000kN.

w Theoretically transferring horizontal force with no limitations

w Accommodating horizontal movement with no limitations

w Typically allowing rotation capacity up to ±0.05rad, can particularly applied in curved bridge.

w Convenient to manufacture and install

w High reliability, durability and easy maintenance


4. Types

GTS bearings are generally classified into the followings three categories:

GTSF ——Fixed bearing which resists horizontal force in every directions but allows rotations about every axis.

1-concave plate 2-spherical PTFE sheet 3-convex plate 4-flat PTFE sheet 5-SS plate 6-sleeve 7-top plate 8-anchor bolt

GTSG ——Guided sliding bearing which resists horizontal force in only one direction and slides along the perpendicular direction, and allows rotations about every axis as well.

1-concave plate 2-spherical PTFE sheet 3-convex plate 4-flat PTFE sheet 5-SS plate 6-sleeve 7-top plate 8-anchor bolt

GTSM ——Free sliding bearing which allows movements in every direction with no horizontal resistance and rotations about every axis.

1-concave plate 2-spherical PTFE sheet 3-convex plate 4-flat PTFE sheet 5-SS plate 6-sleeve 7-top plate 8-anchor bolt

5. Raw Material

The materials used are typically in accordance with AASHTO standard, or European standard EN1337 as clients’ requirements.

w The structural components of the bearings are made of ASTM A709/A709M Grade 36 or higher quality.

w PTFE surface are made from virgin PTFE resin or blended with fiber (glass or carbon).

w Hard chromium plate (entire convex surface)to be hard chromium with a minimum thickness of 100microns.

w Stainless steel conform to the requirements of ASTM A240/A240M, Type 304 with a minimum thickness of 20 gage.

6. Anchorage system

Anchorage system is used to connect the superstructure and substructure and resist the horizontal force. Typically:

w For steel structure

1. Shear pins

2. Anchor bolts

w For precast concrete structure and cast in situ structure

1. Shear pins

2. Anchor bolts connecting to masonry plate

3. Anchor bolts connecting to threaded socket