Two Phase Seismic Bearing

1. Principle

GT-KZ two phase seismic bearing is a combination of conventional bearing and two restrainers, one fuse restrainer and one non-fusible restrainer. The restrainers, which have a pre-established force threshold, are rigidly connected to the bearing in order to avoid relative displacement under service load condition. Then bearings dissipate energy and prevent collapse of bridge deck by two phases:

i. Phase 1: During the design earthquake, disconnect the fuse restrainer with bearing when load exceeds the pre-set threshold to dissipate energy.

ii. Phase 2: After sliding to a pre-set movement condition, the non-fusible restrainers prevent collapse of bridge deck.

2. Structure

w Conventional structural bearing, including pot bearing, spherical bearing, etc.

w Fuse restrainer disconnect when load exceed the preset threshold (No. 9).

w Non-fusible restrainer prevent the collapse of bridge deck (No. 7).

3. Application and Advantage

Two Phase Seismic Bearing can be widely engineering applied since the following superior performance:

w All the conventional structural bearings’ characteristics

w Seismic and Collapse-proof capacity

w A more economical solution of seismic isolation

w Convenient to manufacture and install

w High reliability, durability and easy maintenance

4. Types

Two Phase Seismic Bearing can be classified into free, guided and fixed types.

5. Raw Materials

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