Bridge Bearing | EQS

Bridge Bearing | EQS

| Basic concept

A base isolation unit that, even in case horizontal force is applied to EQS in any direction at the time of earthquake, is able to absorb and dissipate most of seismic force in a way that disk bearing specially designed for mutual base isolation between structures of upper and lower part of bridge part to be smoothly made and mass energy regulator (MER) securing structural stability by rigidly resisting against horizontal load applying at ordinary times and earthquake with compressed deformation are combined each other.

| Key parts and functions

Structure drawing	Mark	Name	Material	Key functions
	1	Disk	Polyurethane	1. Accommodating vertical load 2. Accommodating rotative distortion
	2	MER Spring	Polyurethane	1. Constant horizontal force resistance 2. Recovery function at earthquake 3. Constant horizontal rigidity factor 4. The second rigidity factor at earthquake
	3	Friction plate for base isolation	Fluoro resin plate(PTFE)	1. Accommodating constant displacement 2. Friction damping function at earthquake 3. The first rigidity factor at earthquake
	4	Shearing pin	High strength steel material	Transfer horizontal load
	5	Guide box	SM490	1. Protects main material of bearing support 2. MER Spring expansion resistance

| Features of EQS

1. Applicable to all bridges with small, medium and long spans regardless of upper structure style. Particularly good applicability to bridges with small and medium spans.
2. Simple style and structure and relatively low product height allowing excellent applicability to maintenance of existing bridges with conventional type of bridge bearing installed.
3. Due to the energy absorption bearing that is able to absorb and dissipate most of earthquake loads, it is possible to secure stability against earthquake by replacing bearing only without earthquake-proof reinforcement of existing bridges structures not designed for earthquake-proof, allowing an outstanding applicability to establish earthquake-proof stability of existing bridges with no earthquake-proof design.
4. At the time of replacing conventional type bridge bearing of existing bridge, it is almost not required to expand coping width for securing edge distance as bearing area is small compared to other energy absorption bearings in case of equivalent vertical capacity.
5. As MER and Disc made of polyurethane are not sensitive to temperature compared to rubber, it keeps good applicability even in area with large temperature difference yearly.
6. As earthquake horizontal strain quantity can be minimized compared to other energy absorption bearing under the same design condition, it is possible to clear the structural instability caused by relative over-displacement of upper and lower part structure at the time of earthquake.
7. Bridge axis and compression stiffness in the direction perpendicular to bridge axis of mass energy regulator can be differed respectively, allowing easy and economy of design.
8. Durability was proved by experience of installation for a long time and various testing institutes with public confidence so there is no need of maintenance unless it is caused by any separate external problem.
9. Advantage of making it possible to design a very useful system simply replaceable by disassembling reaction plate assembly bolt without pulling up the upper part in case of replace mass energy adjusting device if required.
10. Maintenance is very simple as replacement is concluded after checking capability based on stiffness test by easily installing/removing mass energy adjusting device only without Jack up.
11. As superstructure restoration of upper part structure after earthquake is made for itself by compression stiffness of mass energy adjusting device with good durability, the superstructure cost loss can be largely reduced.

| EQS_Type

| Impact load dispersion-type earthquack-proof bridge support

AASHTO, "Guide Specifications for seismic Isolation Design. 13. Required Tests of Isolation System" specifies that capability of base isolation bearing support shall be verified in accordance with following standards.

| Prior capability verification test of EQS
- HITEC EQS Base isolation bearing support capability verification test items and test results