Products Description
Introduction
Seismic isolation protects buildings and bridges by decoupling the superstructure from destructive ground motion. Elastomeric isolators, friction pendulum bearings, viscous dampers and buckling-restrained braces all require strict performance validation before they can be supplied to construction projects. Among all verification activities, type testing stands out as the formal design-level qualification test accepted in European, ISO and many international tender specifications.
Many engineers, buyers and suppliers confuse type testing with prototype testing or routine factory tests. This article clarifies the definition, mandatory test scope, regional standard rules and common pitfalls for seismic isolation type testing.
What is Type Testing in Seismic Isolation?
Type testing is a series of standardized, third-party witnessed tests carried out on representative full-scale specimens of a defined product type, to verify that the entire design meets specified mechanical, seismic and durability requirements.
Once successfully completed, a valid type test certificate covers all production units manufactured under the same design, raw material specification, geometry and production process. It qualifies the design itself, not just one single sample.
This is the fundamental principle: type testing qualifies the design; routine tests check individual finished goods; prototype testing validates a first-of-kind custom sample for a specific project.
Seismic isolation devices that require type testing:
Laminated rubber bearings (NRB, LRB, HDRB)
Friction pendulum bearings (FPS, TFPB triple friction pendulum bearings)
Viscous fluid dampers (VFD)
Buckling-restrained braces (BRB)
Sliding isolation bearings for buildings and bridges
Type Testing Requirements by Region & Standard
Europe: EN 15129 / EN 1337
EN 15129:2018 Anti-seismic devices gives the formal definition of type testing, and it is a mandatory prerequisite for CE marking of anti-seismic devices placed on the EU market.
Specimens shall be representative of the product type. Any major modification triggers re-type testing: rubber compound change, friction material change, critical dimension adjustment, vulcanization process change or modification of steel reinforcement layout. Factory Production Control (FPC) runs in parallel with type testing as ongoing surveillance for mass production.
ISO: ISO 22762 Series
ISO 22762 defines type tests for elastomeric seismic isolators and sliding isolators. It separates three test categories clearly: type test, prototype test and routine production test. ISO 22762 is widely adopted in Asia, Oceania and international bridge projects.
United States Market
US codes including ASCE 7, ICC-ES and OSHPD do not use the term type testing as the primary formal phrase. The equivalent procedure is seismic prequalification testing. Even so, international project specifications in the US market often retain type test in tender documents for easier alignment with European suppliers. OSHPD prequalification is the most rigorous pre-production qualification route for California seismic isolation projects.
China
GB/T 20688 does not adopt the literal term type testing. The matching mandatory qualification activity is design qualification test, required before large-scale supply of seismic isolation bearings for building isolation projects.
Typical Test Items for Isolator Type Testing
For elastomeric isolators and friction pendulum bearings, a complete type test package usually includes:
Vertical compression stiffness test
Horizontal cyclic shear test at design displacement and design load
Equivalent damping and hysteresis curve measurement
Ultimate displacement and stability test
Fatigue cyclic test for long-term repeated loading
Tensile capacity test (rubber isolators)
Dependence tests: load, frequency, temperature effect
Aging and environmental exposure tests (for high-durability grades)
For viscous dampers and BRBs, the test matrix is adjusted to focus on velocity-dependent force, cyclic stability and buckling resistance.
Type Testing vs Prototype Testing vs Routine Test
|
Item |
Type Testing |
Prototype Testing |
Routine / Factory Test |
|
Core purpose |
Qualify a product design for batch supply |
Verify custom first article for a specific project |
Check every or sampled finished unit |
|
Valid scope |
All identical units of this design |
Only that tested prototype |
Individual production piece |
|
Standard status |
Defined in EN 15129, ISO 22762 |
Not a formal standard term |
Defined as factory QC |
|
Re-test trigger |
Design, material or process change |
New custom geometry or project parameter |
Non-conformance found in production |
|
Use case |
CE certification, pre-qualification, vendor approval |
R&D validation, one-off special design |
Delivery inspection, batch release |
When Must You Repeat Type Testing?
A passed type test report does not last indefinitely. Re-testing is mandatory when:
The rubber formulation, friction material or steel material grade changes
Core dimensions, layer layout or bonding design are modified
Vulcanization, forming or assembly processes are adjusted
Surveillance audits identify consistent performance drift
The specification or target seismic demand is upgraded beyond original test coverage
Common Misconceptions in International Tenders
Prototype test = type test: This is one of the most frequent disputes. A prototype test report from one custom sample cannot replace a valid type test certificate for design qualification.
Routine test reports can substitute type testing: Factory batch tests only prove that a single bearing meets acceptance limits; they do not qualify the whole design.
One type test covers all sizes: Most standards require separate type testing for families outside defined scaling ranges.
Conclusion
Type testing is the backbone of quality assurance for global seismic isolation supply chains. It provides independent, repeatable proof that an isolator or damper design reliably meets seismic performance targets, and it is the key document for CE marking, prequalification, vendor approval and tender compliance.
For structural engineers, project owners and suppliers, clear separation between type testing, prototype testing and routine testing avoids technical disputes, reduces certification risk and simplifies cross-border project acceptance.
