Paul Bonnet – Oxford University – Developing Real Time Substructure Dynamic Testing (RTS testing)

The problem: analyse the behaviour of a structure in an earthquake Let’s do a computer model of the structure Let’s build a replica of the structure on a shaking table Let’s conduct a pseudo-dynamic test on the structure All these methods have their inherent drawbacks All these methods have their inherent drawbacks Modelling cracks, fatigue, concrete, strain rate effects, etc. Scale effects and/or load capacity & cost No experimental velocity and inertial effects Let’s conduct a real-time substructure test

1 numerical substructure + 1 physical substructure + 1 emulation interface The idea behind RTS testing: divide structure into a part solved numerically and a part tested physically. separatebutcomplementary ensuring correct boundary conditions on each substructure affect each other at all times For a RTS experiment to work, the 2 substructures and the interface emulation need to be solved / tested / conducted SIMULTANEOUSLY & in REAL-TIME. have dynamic effects

Example: behaviour of a dynamically isolated 10 storey building during an earthquake?

Benefits of RTS testing: Structural parts of interest => physically tested with the rest offering an infinite repeatability. Complete structure is emulated with much lower cost & capacity than shaking table test. Dynamic effects are exact because reproduced in real-time. => Practical & financial benefits while retaining good scientific validity.

Results of preliminary tests:

Challenges / current work: Quick numerical substructure computation. => Using discrete time integration scheme (several schemes to compare). “Instantaneous” actuation is not possible (presence of an “actuator delay” → instability). => Need to know how much delay, minimise it, know how & why it varies. => Need to compensate for actuation delay (several methods to compare). Method needs to be applied & proven for non-linear numerical & physical substructures of earthquake engineering size & properties. => Conduct a validation test on a 2 storey building column.

If you’d like to know more… …come and visit us in the Oxford University Structural Dynamics Laboratory Tel: