Paul Bonnet – Oxford University – [email protected] Bonnet – Oxford University – [email protected]
Developing Real TimeDeveloping Real TimeSubstructureSubstructure
Dynamic TestingDynamic Testing
(RTS testing)(RTS testing)
The problem:The problem:analyse the behaviour of a structure in an earthquakeanalyse the behaviour of a structure in an earthquake
Let’s do aLet’s do acomputer model ofcomputer model of
the structurethe structure
Let’s build aLet’s build areplica of the structure replica of the structure
on a shaking tableon a shaking table
Let’s conductLet’s conducta pseudo-dynamic test a pseudo-dynamic test
on the structureon the structure
All these methods All these methods have their inherent have their inherent
drawbacksdrawbacks
Modelling cracks, fatigue,Modelling cracks, fatigue,
concrete, strain rate effects, etcconcrete, strain rate effects, etc..Scale effects and/orScale effects and/orload capacity & costload capacity & cost
No experimental velocity and No experimental velocity and inertial effectsinertial effects
Let’s conductLet’s conducta real-time substructure a real-time substructure
test test
1 numerical substructure1 numerical substructure
++
1 physical substructure1 physical substructure
++
1 emulation interface1 emulation interface
The idea behind RTS testing:The idea behind RTS testing:divide structure into a part solved numerically and a part divide structure into a part solved numerically and a part
tested physically.tested physically.
separateseparate
butbut
complementarycomplementary
ensuring correct ensuring correct boundary conditions boundary conditions on each substructureon each substructure
affect each affect each other at all other at all
timestimes
For a RTS experiment to work, the 2 substructures and the For a RTS experiment to work, the 2 substructures and the interface emulation need to be solved / tested / conducted interface emulation need to be solved / tested / conducted
SIMULTANEOUSLYSIMULTANEOUSLY & in & in REAL-TIMEREAL-TIME..
have dynamic have dynamic effectseffects
Base isolators
M Top motion: xt
Ground motion: xg
Building structure
Passive mass-damper
P C
xtM
F2
F1
Actuator
Emulated system = Physical substructure + Interface + Numerical substructure
Base motion: xb
xb
xb
F2
xtF1
Example:Example:behaviour of a dynamically isolated 10 storey building behaviour of a dynamically isolated 10 storey building
during an earthquake?during an earthquake?
Benefits of RTS testing:Benefits of RTS testing:
Structural parts of interest => physically tested Structural parts of interest => physically tested with the rest offering an infinite repeatability.with the rest offering an infinite repeatability.
Complete structure is emulated with much lower Complete structure is emulated with much lower cost & capacity than shaking table test.cost & capacity than shaking table test.
Dynamic effects are exact because reproduced Dynamic effects are exact because reproduced in real-time.in real-time.
=> Practical & financial benefits while retaining => Practical & financial benefits while retaining good scientific validity.good scientific validity.
Results of preliminary tests:Results of preliminary tests:
Results of preliminary tests:Results of preliminary tests:
Challenges / current work:Challenges / current work:
Quick numerical substructure computation.Quick numerical substructure computation.=> Using discrete time integration scheme (several schemes to => Using discrete time integration scheme (several schemes to compare).compare).
““Instantaneous” actuation is not possible (presence of an “actuator Instantaneous” actuation is not possible (presence of an “actuator delay” delay” → instability→ instability).).=> Need to know how much delay, minimise it, know how & why it => Need to know how much delay, minimise it, know how & why it varies.varies.=> Need to compensate for actuation delay (several methods to => Need to compensate for actuation delay (several methods to compare).compare).
Method needs to be applied & proven for non-linear numerical & Method needs to be applied & proven for non-linear numerical & physical substructures of earthquake engineering size & properties.physical substructures of earthquake engineering size & properties.=> Conduct a validation test on a 2 storey building column.=> Conduct a validation test on a 2 storey building column.
If you’d like to know more…If you’d like to know more…
……come and visitcome and visitus in the Oxfordus in the OxfordUniversity StructuralUniversity StructuralDynamics LaboratoryDynamics Laboratory
[email protected]@eng.ox.ac.uk Tel: 01865 273 112 Tel: 01865 273 112