World first: Cross-fault bi-axial earthquake simulation

Researchers from China's Southeast University conduct the world's first simultaneous vertical & horizontal earthquake simulation on the dual-table seismic simulator at CCRDI.

In July 2018, researchers from Southeast University in China successfully completed the world’s first 'x' (horizontal) & 'z' (vertical) simultaneous-excitation dual-table earthquake simulation test of a steel-reinforced concrete bridge-frame designed for cross-fault installation.

The test was conducted on the 3m x 6m dual-table seismic simulation shake tables at CCRDI (China Merchants Chongqing Communications Technology Research & Design Institute). Servotest supplied CCRDI’s cutting-edge twin shake table system, while BBK (our agent in China) provided local consultancy and service in support of this successful test.

The importance of this testing is recognised by leading researchers within the physical mechanical simulation (shake-table) and bridge structures field. It is significant due to the major expansion of road traffic construction. Many bridges in high-intensity earthquake regions face the possibility of crossing active fault-lines and so need to be tolerant of the complex ground-motions associated with seismic events.

While computer-based modelling and simulation are widely used in the seismic simulation area, realistic mechanical simulation is also essential due to non-linear behaviour and other aspects that simply can't be predicted or modelled effectively. Until now testing of cross-fault bridge structures has been focused on 'x' (horizontal) motions only, to simulate the effect of fault-slip during a seismic event. This restriction has been largely due to the capability of simulation devices to apply motions safely & accurately.

However, with the two 6m x 3m six degree-of-freedom seismic tables at CCRDI, the destructive forces that are likely to be applied to bridge frame structures in cross-fault applications, can be simulated more accurately by applying both 'x' (horizontal) and 'z' (vertical) motions simultaneously to both of the bridge frame supports. This more realistic simulation of multi-parameter complex force conditions is intended to lead to further improvements in the resilience of such bridge structures to real-world seismic events.

A short video-clip of this testing can be viewed on the Servotest YouTube channel by following this link dual-table test at CCRDI.