1. Hybrid Experimental Analysis of Semi-active Rocking Wall Systems K.J. Mulligan, M. Fougere, J.B. Mander, J.G. Chase, G. Danton, R.B Elliott Departments of Mechanical and Civil Engineering, University of Canterbury, Christchurch B.L Deam Leicester Steven EQC Lecturer in Civil Engineering, University of Canterbury, Christchurch Sponsor: EQC Research Grant # 03/497

2. Why use Semi-active system? Provide a broad range of control - respond to changes in structural behaviour Provide supplemental damping for all rocking cycles, not only subsequently larger cycles Provide resistive forces when most benificial to system

3. Device Dynamics Valve Piston Cylinder Two chambered design: -Utilises each side independently -Resetting can occur at any prescribed point of piston displacement -Portions of motion may dictate both valves to be open Valve and valve controller Resetable Device Test Machine Test Jig

4. Rocking Wall Dynamics Fd WrFd O b h Wr Roof R OO’

5. Hybrid Testing Physical system Measured Force and Displacement Displacement command Valve Control Virtual System

6. Hybrid Testing Procedure Wall model calculations determine rotation of wall depending on applied forces Rotation of the wall converted into linear displacement for actuator, signal sent to the dynamic test rig Valve control determined for current time step Dynamic test rig supplies displacement to physical semi-active device Force developed in device returned to virtual system and used in subsequent time-step calculation.

7. Analysis Procedure Normalised to uncontrolled case Presented as: -peak reduction factors, R.F -equivalent viscous damping, ξ Suite of ground motions used to analyse efficacy of semi-active system to a variety possible events.

8. Results Rotation about point 0’ Rotation about point 0Uncontrolled Controlled

9. Device Reponse Displacement (m) Device Force (N)

10. Change in Structural Period

11. Comparison with Analytical Model a) hybrid result b) analytical result

12. Full Scale Rocking Wall MetricK=1000 kN/mK = 5000 kN/mK= 10000kN/m R.F geometric mean 1.011.141.21 R.F multiplicative variance 1.101.271.43 ξ geometric mean 5.115.47 7.12 ξ multiplicative variance 1.152.132.30

13. Summary Significantly reduce peak rotations of seismically excited rocking wall systems Provide additional restoring forces to the system when it is most benifical Model accurately predicts test results allowing scaling to a variety of applications Results are dependent on ground motion, hence important to examine using a suite of ground motions