International Standard for Elastomeric Seismic-Protection Isolators – ISO 22762

Table 1. Overview of ISO 22762 Structure (as of April 2024)

Test Methods	Product Specifications	Guidance and Informational
Part-1: Test methods	Part-2: Applications for bridges – Specifications
	Part-3: Applications for buildings – Specifications
Part 5: Sliding seismic-protection isolators for buildings		Part-4: Guidance on the application of ISO 22762-3
Part-6: High-durability and high-performance specifications and test methods		Part-7: Relationship of the ISO 22762 series to the design and testing of seismic isolation systems (under development)

Overview of the Standards                                                                       

Part 1: Test Methods, Part 2: Applications for bridges – Specifications, and Part 3:  Applications for buildings – Specifications

The core standards in the ISO 22762 series are Parts 1, 2 and 3. Part 1 specifies test conditions, test procedures, testing equipment, measurement accuracy, methods for calculating characteristic values, and methods for summarizing test results of each evaluation item for elastomeric seismic isolation bearings and their component materials. The product standards, Part 2 for bridges, and Part 3 for buildings, consist mainly of classifications, requirements, and design rules, and in particular, specify various required test items for horizontal and vertical properties of seismic isolation bearings. In Parts 2 and 3, the required values of properties are kept to a minimum. In Part 6, which is described below, reference values for each required property are defined in detail and that standard also introduces the concept of grade levels which are based on the required performance. Table 2 shows the various properties and test items for type tests and routine tests, which are also commonly known as prototype tests and production tests in various building codes.

Table 2. Type Test and Routine Test Items (Part 3)

Part 4: Guidance on the application of ISO 22762-3

This standard provides guidance on the ISO 22762-3 and includes examples of design calculations as well as typical properties and test results for all types of elastomeric isolators.

Part 5: Sliding seismic-protection isolators for buildings

This standard specifies minimum requirements and test methods for elastomeric sliding isolators used for buildings and the rubber material used in the manufacture of such isolators

Part 6:  High-durability and high-performance specifications and test methods

The Japanese Industrial Standard (JIS) K 6410 “Elastomeric seismic-protection isolators for buildings” was developed based on ISO 22762 and was published in 2011. After JIS K 6410 was established, revisions were proposed to ISO, feedback was provided in the periodic ISO reviews, and revisions were made on a case-by-case basis. In this way, both standards have evolved in the general flow of ISO→JIS→ISO. Of the ISO 22762 series of standards, only Part 6 was developed after JIS K 6410. Part 6, “High-durability and high-performance specifications and test methods” was initially developed by JIS K 6410 and then proposed to ISO. In Part 6, standard values for each characteristic property are defined in detail, and the concept of grades is also introduced. As shown in Figure 1, there are three grades, or performance levels, I, II, and III. Grade I is the conventional level of performance specified in Part 3, and for Grades II and III, new test items are added in addition to the specification of standard values. The grades are intended to allow users to select a performance level of seismic isolation bearing appropriate to the importance of the structure to be isolated. For example, the highest performance level, Grade III, is intended for seismic isolation of nuclear facilities, Grade II for emergency response facilities (hospitals, fire stations, etc.), and Grade I for residential houses

Part-7: Relationship of the ISO 22762 series to the design and testing of seismic isolation systems

ISO 22762 was largely developed based on the performance and quality requirements and design methods for seismic isolation bearings in Japan, and through extensive contributions from participating countries, was refined to reflect the contemporary status of seismic isolation worldwide. Figure 2 shows countries and regions where seismic isolation is utilized and the standards for seismic isolation bearings that are used. In various earthquake-prone regions in the world, outside of Europe and New Zealand, the U.S. national standard, ANSI/SEI ASCE-7 “Minimum Design Loads and Associated Criteria for Buildings and Other Structures” which provides design requirements for seismically-isolated structures but no detailed requirements for seismic isolation bearings, is often used. Several countries have more detailed standards for seismic isolation bearings, such as in China where GB206885, a modified version of ISO 22762 is used, and in Europe, European standard EN 15129 exists, but the requirements in these standards vary and the level of detail is inconsistent. Therefore, ISO TC45 / SC4 / WG9 has undertaken a new initiative to prepare guidelines to enable seismic isolation designers around the world to utilize ISO 22762, mainly focusing on ASCE 7, which is the most widely-used baseline standard for design of seismically-isolated buildings worldwide. These new guidelines will be “Part 7: Relationship of the ISO 22762 series to the design and testing of seismic isolation systems”. In the development of Part 7, experts in seismic isolation design from around the world participated in the WG9 development process. Table 3 gives the typical design terms used in ISO 22762 Part 7 and in major international building codes such as ASCE-7.

Table 3. Typical Design Terms and Definitions in ISO 22762 and in Major International Building Codes (Part 7)

Future Direction

Standardization is very important to ensure both the consistent use of seismic isolation technology, and also to help facilitate its spread and growth around the world. The ISO 22762 standardization activity has, and will continue to, contribute to providing a more user-friendly environment for structural engineers and manufacturers involved in seismic isolation. WG9 will continue to work on the development, refinement of ISO 22762 and to promote the use of seismic isolation for the betterment of society worldwide.

Acknowledgements

I would like to thank all members of ISO TC45/SC4/WG9 and The Japan Rubber Manufacturers Association for their contributions to the development of ISO 22762.

References:
[1] International Organization for Standardization, Elastomeric seismic-protection isolators, ISO 22762:2018.
[2] Murota, N., Kelly, J.M., Fuller, K.N.G., Zhou F.L., Nishi, T., Yoshizawa, T., Sudou, C., and Yazaki, F.: “New International Standard for Elastomeric Seismic Protection Isolators”, Proceedings, 5^th National Seismic Conference on Bridges and Highways, Sept. 18-20, 2006, San Francisco, USA.
[3] Nishi T., Murota, N.: “A Survey of Specifications for Design and Testing of Seismic Isolators – Comparison of ISO 22762, EN 15129, and JIS K 6410” -., Proceedings,13^thWorld Conference on Seismic Isolation, Energy Dissipation and Active Vibration Control of Structures, Sep. 24-27, 2013, Sendai, Japan.