Earthquake Vibration (Seismic) Testing

Earthquakes induce damaging ground vibration characterised by low frequency content and high displacements. Products intended for use in earthquake prone areas must therefore be designed to ensure they can withstand earthquake-induced vibration. However, as the vibration induced by earthquakes is highly complex, the resilience of a product to earthquake vibration cannot be determined with great confidence by modelling alone. Therefore, physical testing remains the only reliable method of verifying the performance of products under earthquake conditions.

However, for numerous reasons, the conduct of earthquake vibration testing is not easy and few test houses are able to carry out such testing in a credible way. Drawing upon decades of experience in vibration testing in other challenging areas such as naval and aerospace domains, our engineers have been heavily engaged in developing solutions for seismic vibration testing over the last 12 months. As a result of these efforts, Austest Laboratories is pleased to announce significant expansions in this area and the new capability to conduct earthquake vibration testing of equipment and other products.

The new capability was made possible by the development of an in-house software for deriving the required random vibration profile. Unlike many of the commercially available earthquake vibration testing software packages that use wavelet combinations, our software relies on a genuinely random vibration profile and thus more accurately replicates earthquake ground motion and closely matches the standard requirements. Moreover, unlike the off-the-shelf solutions, our software ensures that we can meet the requirements of even the most challenging earthquake vibration testing standards such as IEE344 which insist that the frequency/amplitude content of the waveform is statistically constant with time over the strong motion part of the test.

In parallel with the development of the profile-deriving software, our team has designed and implemented modifications of a custom-made electrodynamic shaker in operation at our Sydney facility, which now features increased payload as well as a high-displacement capability which exceeds standard vibration testing machines of this type operated by other providers.

These new developments ensures that Austest Laboratories is now able to provide earthquake vibration testing services of the highest quality and fully meet the requirements of standards like IEE344 and AC156 for testing the resilience of products to severe earthquakes for products with natural frequencies as low as 2.4 Hz. For practicable purposes this covers nearly all mechanically or electrically powered equipment and all items on vibration mounts.

If you are interested in learning more about earthquake vibration and problems associated with seismic testing we recommend an article published by our senior mechanical test engineer Prabakaran Naganathan or contact us if you have any further questions.