A six-storey mixed-use project in the West Perth precinct had the structural team concerned about drift during a Meckering-type event. The underlying Bassendean Sand isn't the problem—it's the spectral acceleration demands that sneak up on you with soft soil amplification. We modelled several lead-rubber bearing configurations against the AS 1170.4:2007 design spectra and landed on a solution that kept inter-storey drift below 0.5%. For projects on the Swan Coastal Plain, combining a seismic microzonation study with isolator prototyping is the most defensible path through the DA process. Perth sits in a low-to-moderate seismic hazard zone, but the recurrence of magnitude 5.5+ events in the Southwest Seismic Zone means base isolation often becomes the differentiator between a code-compliant structure and one that's genuinely resilient. We run the full cycle: hazard assessment, isolator specification, and validation testing in our Osborne Park lab.
Base isolation in Perth is about managing amplification on deep sands, not just resisting a rare event—the isolator period must stay below the soil's fundamental period to avoid resonance.
Approach and scope
Site-specific factors
The test rig we operate in Osborne Park applies axial loads up to 10 MN while cycling bearings through shear strain amplitudes that replicate the code-level event. Three actuators run simultaneously to simulate bidirectional horizontal motion plus overturning moment—this matters in Perth because the 1968 Meckering earthquake showed that intraplate events can deliver significant vertical components. A bearing that passes unidirectional testing but fails under combined loading is exactly the kind of latent risk an isolation design must eliminate. We test for scragging recovery, low-temperature stiffening (relevant for winter morning pours on site), and aging effects over a 50-year design horizon. If the isolator's effective stiffness shifts more than 15% during the aging protocol, we reject that rubber compound and reformulate.
Relevant standards
AS 1170.4:2007 – Structural design actions, Part 4: Earthquake actions in Australia, AS 5100.2:2017 – Bridge design, Part 2: Design loads (seismic isolation provisions), ISO 22762-1:2018 – Elastomeric seismic-protection isolators, EN 15129:2018 – Anti-seismic devices (for friction pendulum systems)
Related technical services
Isolator Design & Specification
We prepare project-specific isolation system designs including bearing layout, effective period and damping targets, displacement demand under MCE, and wind restraint detailing. Each design package includes the full load path analysis and isolator schedule ready for tender documentation.
Prototype & Production Testing
Full-scale dynamic testing of isolator prototypes and production samples in our NATA-accredited laboratory. Reports cover effective stiffness, equivalent viscous damping, scragging recovery, and aging effects, all traceable to ISO 22762 requirements.
Typical parameters
Top questions
Is base isolation necessary in Perth given the low seismic hazard?
Perth's hazard factor Z ranges from 0.08 to 0.12, which is low by global standards. However, site amplification on the deep Bassendean Sands can double spectral acceleration demands, and the Southwest Seismic Zone has generated events above magnitude 6.0. Base isolation becomes cost-effective when post-earthquake functionality is a design objective—particularly for hospitals, data centres, and emergency response facilities.
What does base isolation design cost for a typical Perth project?
For a mid-rise commercial building in the Perth area, the design and testing package typically falls between AU$6,550 and AU$11,600, depending on the number of isolator prototypes and the complexity of the testing protocol. This covers hazard assessment, isolator specification, prototype fabrication oversight, and full-scale dynamic testing.
How long does the isolator testing phase take?
Once prototypes are fabricated, the testing programme runs approximately four to six weeks. This includes conditioning, scragging cycles, full dynamic characterisation at multiple strain levels, aging protocols, and final reporting. We coordinate closely with the project programme to avoid delays to the foundation package.
Do you handle both building and bridge isolation projects?
Yes, we design and test isolators for buildings under AS 1170.4 and for bridges under AS 5100.2. The bridge isolation work often involves larger displacement demands and requires friction pendulum systems, which we test on the same rig with adapted loading protocols.