Ultra‑Low‑Frequency Seismic Isolation Systems
ISVPL designs and supplies steel mass‑spring base‑isolation systems tuned down to about 1.4 Hz vertical and 1.0 Hz horizontal, reducing seismic demands on buildings and critical infrastructure in high‑seismic zones.[web:155][web:266][web:272]
The challenge: protecting structures in M7–8+ earthquakes
In severe earthquakes, conventional strength‑based design may not be enough. Long‑period S‑ and P‑wave components can excite a building’s natural modes, driving accelerations and inter‑story drifts beyond what columns, joints and non‑structural elements can safely sustain.[web:266][web:272]
Seismic isolation changes the problem: instead of making the superstructure ever stronger, it reduces the input motion by inserting a flexible, energy‑dissipating layer between the ground and the structure, lowering seismic force demands and damage probability.[web:155][web:268]
ISVPL solution: steel mass‑spring base isolation
ISVPL’s isolation technology is based on modular steel mass‑spring units installed at the foundation level. These units are tuned so the isolated structure has a much longer effective period and lower stiffness at the isolation interface.
- Vertical natural frequency around 1.4 Hz and horizontal around 1.0 Hz, giving isolation crossover near 1.98 Hz and 1.41 Hz respectively.
- Significant reduction in accelerations transmitted to the superstructure, lowering inertia forces, inter‑story drifts and damage.[web:155][web:268]
- Three‑dimensional behaviour, providing both horizontal and vertical isolation, which is uncommon in many traditional systems.[web:269][web:275]
- Modular design enabling tailoring for different loads, stiffness and retrofit constraints.
Priority applications
ISVPL’s steel mass‑spring isolation systems are intended for projects where continued operation and rapid post‑event recovery are critical.
- High‑rise buildings in seismic zones 3 and above
- Hospitals, control centers and emergency facilities
- Data centers and financial / communications hubs
- Thermal and nuclear power plants and key utilities
- Research labs, semiconductor fabs and precision facilities
- Metro and rail infrastructure interfaces with buildings
Seismic isolation services around the product
- Feasibility and screening studies for isolation vs. strengthening
- Concept development and preliminary sizing of isolation systems
- Detailed design support: stiffness, damping, displacement checks and interface detailing with structural engineers.[web:272][web:268]
- On‑site installation guidance, commissioning and monitoring
- Post‑event inspection and performance evaluation
Key isolation parameters
- Vertical natural frequency
- ≈ 1.4 Hz
- Horizontal natural frequency
- ≈ 1.0 Hz
- Isolation crossover (approx.)
- ≈ 1.98 Hz (V), ≈ 1.41 Hz (H)
- Target attenuation
- ≈ 42 VdB over 0–250 Hz band
- Isolation dimensions
- Horizontal + vertical (3D)
Benefits of base isolation
- • Lower accelerations and inter‑story drifts, reducing structural and non‑structural damage.[web:155][web:266]
- • Reduced downtime and faster functional recovery after strong earthquakes.
- • Retrofit option for some existing buildings where strengthening the superstructure is complex or intrusive.[web:268][web:272]
- • Concentrates seismic demands in replaceable isolation hardware instead of primary structural elements.[web:271][web:275]
Considering seismic isolation for a project?
Share your building type, location, seismic zone and performance objectives. ISVPL can prepare an initial isolation concept and discuss feasibility with your structural design team.
Contact seismic isolation team