Biaxial Seismic Simulator

Biaxial Seismic Simulator with a Laminated Shear Stack option

For reproducing realistic earthquake events in a laboratory with a moderate research budget using a compact system

Digital Model Table

Earthquakes result in about 13,000 fatalities and more than AUD$40bn in infrastructure damage around the world each year. In Australia, history shows earthquakes may occur in places with no previous seismic activity, and cities are at risk as they comprise old infrastructure made of unreinforced masonry that is particularly susceptible to earthquake damage. Reinsurance companies rate an earthquake in Sydney in their 20 top risk exposures worldwide.

Research is needed to understand how infrastructure responds to earthquakes, using seismic simulators to conduct controlled laboratory tests in which large models are subjected to earthquake loading.

Most earthquake damage is caused by a combination of significant horizontal and vertical shaking. However, the seismic simulators used by many researchers move in just one horizontal direction, posing limitations on the relevance and usefulness of the results they generate.

This low cost biaxial simulator has been developed by UNSW, taking advantage of the actuation and control technology offered by Servotest (a world-leading supplier of seismic simulation systems).

It enables combined horizontal (lateral) and vertical (heave) motions providing a higher level of simulation realism when compared with uniaxial simulators which move in just one horizontal direction.

The Biaxial Seismic Simulator is ideal for researchers wanting to:

  • enter the earthquake engineering testing field at a low cost
  • upgrade current testing capabilities which may be limited to shaking horizontally
  • make research discoveries that are more relevant and that will have greater impact than possible using other low cost simulators which only shake horizontally

The Biaxial (H and V) Seismic Simulator, unloaded and with combined H and V sine sweepsThe cost of the Biaxial Seismic Simulator is kept low through its use of only two actuators with the same horizontal alignment. This simple design makes the simulator very compact and easy to anchor to a strong floor, and it occupies a relatively small space. The installation costs are far less than required for a six degrees-of-freedom system.

One of the actuators causes the vertical motion using a scissor mechanism, sometimes referred to as the Scott Russell mechanism. The other actuator causes the horizontal motion.

The first simulator of this type has been installed at UNSW. One current project using the simulator involves the development of a new technology to make tailings liquefaction resistant in the event of an earthquake. It is being run in parallel to an ARC funded project led by UWA that also involves UNSW, UniSA, UoW and six mining companies. Another current project is an investigation, with Yokohama National University, into the seismic behaviour of stone walls of Japanese castles.

For further information on the seismic simulator and to get involved in related research projects please contact Associate Professor Adrian Russell at UNSW ( For sales enquiries please contact Mr Peter Rogers at Servotest Testing Systems Ltd ( Further technical information is contained in the brochure.

Specifications Biaxial Seismic Simulator
Maximum Actuator Strokes ± 30 mm (H)± 20 mm (V)
Maximum Specimen Overturning Moment 20 kNm
Maximum Specimen Mass 2.6 tonnes for combined H and V
Maximum Table Accelerations ± 0.6 g (H) @ max. spec. mass± 0.4 g (V) @ max. spec. mass
Maximum Table Velocities ± 0.3 m/s (H) @ max. spec. mass± 0.2 m/s (V) @ max. spec. mass
Test Frequency 0‑20 Hz (H and V)
Input Signals User defined (e.g regular sine sweeps) or for real earthquakes
Footprint 1.5 m x 2.5 m
Simulator Mass 8 tonnes
Specifications Laminated Shear Stack
Internal Dimensions 1.5 m long, 0.6 m wide, 1.55 m high
Number of Lamina 10
Maximum Lamina Strokes ± 40 mm
Lamina Reaction Stiffness Adjustable, 0‑12.25 kg/mm
Rubber Liner (optional) 6 mm thick vulcanised
CPT Penetrometer Mounting Frame (optional) Custom designed, and may permit testing at three locations
Shear Stack Mass 1.1 tonnes

The Biaxial Seismic Simulator, unloaded and with combined horizontal and vertical sine sweeps

A 2.6 tonne payload was shaken using irregular earthquake signals during calibration

The purpose built laminated shear stack

The purpose built laminated shear stack with a CPT penetrometer mounting frame attached. Each of the 10 laminates has an adjustable stiffness