1. Hybrid simulation evaluation of the suspended zipper braced frame Tony Yang Post-doctoral scholar University of California, Berkeley Acknowledgements: Georgia Institute of Technology, University at Buffalo, University of Colorado, Boulder, Florida A&M University Andreas Schellenberg, Bozidar Stojadinovic, Jack Moehle

2. 2 Inverted-V braced frame

3. 3 Suspended zipper braced frame

4. 4 Shaking table test UB

5. 5 Experimental testing Analytical simulation Quasi-static test GT

6. 6 Hybrid simulation test UCB and CUB Advantages: Numerical hard to model. New systems. Economical. Test structure to extreme states. Collapse. Geographically distributed tests. Share resources. Larger and complex structures.

7. 7 Scope of the hybrid simulation test Utilize OpenSees to simulate the analytical elements and use the time-step integration algorithms to solve the equations of motion. Geometry and material nonlinearities are accounted in both analytical and experimental elements. Develop an experimental testing architecture (OpenFresco) to communicate between OpenSees and experimental setup.

8. 8 Test setup - scale

9. 9 Instrumentation

10. 10 Instrumentation

11. 11 Instrumentation

12. 12 physical model of structural resistance analytical model of structural energy dissipation and inertia Dynamic Loading Seismic Wind Blast/Impact Wave Traffic Equations of motion

13. 13 Newmark average acceleration integration method No added numerical damping and unconditionally stable. Form equilibrium equations at next time step Integration algorithm

14. 14 Finite element model Simulation PC Real time PC P-C program Random time interval Model complexity. Processor speed. Communication delay. Dsp Test PC Servo-control program Physical specimen(s) Fixed time interval (@ 1024 Hz) Dsp Force Experimental testing architecture

15. 15 Transformation of displacement dof

16. 16 Equation 3 Transformation of force dof Feedback forces to finite element model Measured forces

17. 17 Movie – 100% Kobe Earthquake

18. 18 Out-of-plane buckling of the braces

19. 19 Out-of-plane buckling of the gusset plate

20. 20 Hysteric responses of the braces Brace axial deformations [in.] -0.500.5 -50 0 50 3 rd story left brace -0.500.5 -50 0 50 -0.500.5 -50 0 50 Brace axial forces [kips] -0.500.5 -50 0 50 -0.500.5 -50 0 50 1 st story left brace -0.500.5 -50 0 50 1 st story right brace 3 rd story right brace 2 nd story left brace 2 nd story right brace

21. 21 Hysteric responses of the zipper columns -0.06-0.04-0.0200.020.040.06 -20 -10 0 10 20 3 rd story zipper column Axial force [kips] -0.06-0.04-0.0200.020.040.06 -20 -10 0 10 20 2 nd story zipper column Axial force [kips] Axial deformations [in.]

22. 22 Analytical verification – roof drift ratio 0 51015 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 Time [sec] Roof drift ratio [%] Experiment Analytical

23. 23 Analytical verification – brace axial forces 051015 -50 0 50 3 rd story left brace 051015 -50 0 50 3 rd story right brace 051015 -50 0 50 2 nd story left brace Brace axial forces [kips] 051015 -50 0 50 2 nd story right brace 0510 15 -50 0 50 1 st story left brace Time [sec] 051015 -50 0 50 1 st story right brace Time [sec] Experiment Analytical

24. 24 Analytical verification - ZC axial forces 051015 -20 -10 0 10 20 3 rd story zipper column Axial forces [kips] 051015 -20 -10 0 10 20 2 nd story zipper column Time [sec] Axial forces [kips] Experiment Analytical Experiment Analytical

25. 25 Movie – 200% Kobe Earthquake

26. 26 Out-of-plane buckling of the braces

27. 27 Geographically distributed test University of California, Berkeley University of Colorado, Boulder

28. 28 UC Berkeley CU Boulder Internet Testing architecture (distributed test) Simulation PC Real time PC Test PC Simulation PC Real time PC Test PC

29. 29 Input ground motions – Kobe (80% - 100%) 0510152025 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 Time [sec] Ground accelerations [g]

30. 30 Hysteric responses of the braces -0.500.51 -50 0 50 3 rd story left brace -0.500.51 -50 0 50 3 rd story right brace -0.500.51 -50 0 50 2 nd story left brace Brace axial forces [kips] -0.500.51 -50 0 50 2 nd story right brace -0.500.51 -50 0 50 1 st story left brace Brace axial deformation [in.] -0.500.51 -50 0 50 1 st story right brace

31. 31 Hysteric responses of the zipper columns -0.1-0.08-0.06-0.04-0.0200.020.040.060.080.1 -50 0 50 3 rd story zipper column Axial Force [kips] -0.1-0.08-0.06-0.04-0.0200.020.040.060.080.1 -50 0 50 2 nd story zipper column Axial Force [kips] Axial deformation [in.]

32. 32 Summary Conducted a system evaluation of the suspended zipper braced frame using hybrid simulation tests. Both material and geometry nonlinearities are accounted in the analytical and experimental elements. Results of the hybrid and analytical simulation tests matched well. This shows the testing methodology works for complex structural system such as the suspended zipper braced frame.

33. 33 Behavior of the suspended zipper braced frame Behave as intended. Many redundancies. Braces buckled out of plane. Zipper columns are effective in transferring unbalanced vertical forces. Beams rotated out of plane, needed to be braced. Results of the hybrid simulation test First hybrid simulation test to combine complex analytical and experimental elements. Excellent match between the hybrid and analytical simulation results. This shows the analytical brace model, solution algorithm and experimental testing architecture works. Conclusions

34. 34 Application of hybrid simulation test Can be used to test multiple sub-assemblies. Larger and more complex structural system. More extreme loading. Can test the structure to extreme states

35. Question? Resource: http://peer.berkeley.edu/~yang/NEESZipper/ Thank you! This work was supported in part by the National Science Foundation under a pre-NEES award number CMS-0324629. Any opinions, findings, and conclusions or recommendations expressed in this document are those of the authors and do not necessarily reflect those of the National Science Foundation.