Seismic Isolator Standard (SIS) Full Summary

SIS aims to achieve post-earthquake continued functionality for critical facilities. It targets controlling earthquake damage within 2% of building replacement cost with 90% reliability, far exceeding the basic collapse-prevention goal of conventional ASCE 7 Chapters 11–22. Unlike ordinary code design that only ensures "immediate occupancy", SIS guarantees buildings and key facilities remain fully operational after strong earthquakes.

SIS isolators adopt 1/3–1/2 lateral stiffness and damping under Design Earthquake;

Provide 2–3 times shear strength and displacement capacity under Maximum Considered Earthquake (MCE);

Structural lateral stiffness margin is 8 times higher, lateral strength margin reaches 1.33 times;

Isolators only meeting ASCE 17 minimum criteria have a 40% collapse probability per FEMA P695, 16 times the 2.5% failure limit for critical structures;

SIS required shear capacity is 4–6 times higher than Eurocode EN15129, while EN1512 isolators have over 90% collapse risk.

Seismic response modification factor fixed at R=1.0;

Main structural lateral drift ≤ 0.003 times height;

Floor spectral acceleration limited to 0.30g (0.05–3s period range);

Non-structural seismic design force fixed at Fp = 0.4Wp;

Developed and calibrated based on real seismic data of 235 functional-loss and 105 fully operational hospitals worldwide.

Scope of Application

All new and retrofitted building seismic isolators;

ASCE Seismic Risk Category IV essential facilities (hospitals, government hubs);

High seismic design category D / E / F buildings;

AASHTO B/C/D seismic performance category bridges, allowing adoption of Category A design rules;

Industrial facilities, large public buildings adopting low-ductility structural systems.

SIS establishes complete testing frameworks:

Manufacturer Qualification Tests: At least 20 isolator models tested in 3 independent credible labs, including multi-directional shake-table tests, aging and environment simulation, sliding surface contamination & abrasion tests;

Capacity Tests (C1–C6): Verify ultimate lateral displacement, shear strength, uplift/tension capacity, rotation performance under MCE load combination;

Dynamic Property Tests (P1–P9): Multi-cycle loading covering service micro-displacement and design seismic displacement;

100% Factory QC Tests: Every isolator must pass full-cycle performance inspection with full traceability;

Strict 50-year service life, aging resistance, fire resistance and environmental durability requirements.

Isolator manufacturers must hold ISO 9001 certification and formal SIS compliance statement;

Appoint dedicated Seismic Isolation Engineer with minimum 10 years industry experience, taking full legal and technical responsibility;

Prohibit borrowing third-party test data; high-damping rubber isolators (damping＞2%) are not SIS approved due to unstable performance over time;

Manufacturers with repeated non-compliance will be disqualified for 20 years.

Must adopt Equivalent Lateral Force + Response History Analysis; response spectrum method alone is not acceptable;

Adopt exclusive SIS load combination: 1.0D + 0.5L + 1.0Eh + 1.0Ev + 0.2S;

Allow all ASCE 7 Table 12.2-1 Category C seismic systems to be used in D/E/F high seismic zones;

Require consideration of P-Δ large displacement effect and eccentric vertical load influence;

Adjacent isolators vertical settlement difference limited to 1/340 of spacing.

Bridge & Special Provisions

SIS provides independent continued functionality criteria for bridges;

Bridge expansion joints and pipelines must reserve 1.1 times MCE displacement plus thermal deformation margin;

SIS applies to bridge isolator retrofits but not existing bridge structural redesign.