Hybrid simulation evaluation of the suspended zipper braced frame

Tony YangTony YangPost-doctoral scholarUniversity 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

Inverted-V braced frame

3

Suspended zipper braced frame

4

Shaking table test

UB

5

Experimental testing

Analytical simulation

Quasi-static test

GT

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

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

Test setup

- scale

9

Instrumentation

10

Instrumentation

11

Instrumentation

12

physical model of structural resistance

analytical model of structural energy dissipationand inertia

Dynamic Loading Seismic Wind Blast/Impact Wave Traffic

Equations of motion

rP ,n n n n nM u Cu u u P

13

Newmark average acceleration integration method

No added numerical damping and unconditionally stable.

Form equilibrium equations at next time step

21 1 / 4n n n n nu u hu h u u

1 1 / 2n n n nu u h u u

Integration algorithm

1 1 r 1 1 1P ,n n n n nM u Cu u u P

2

r 1

4 4 2

P , , , 0

n n n n n

n n n n

F u M u u u u C u u uh h h

u u u u P

14

Finite element model Simulation PC

Real time PC

P-C program

Random time interval• Model complexity.

• Processor speed.• Communication delay.

Dsp

Dsp

Test PC

Servo-control program

Physical specimen(s)

Fixed time interval (@ 1024 Hz)

DspForce

Force

Force

Experimental testing architecture

15

Transformation of displacement dof

16

Equation 3

Transformation of force dof

Feedback forces to finite element modelMeasured forces

17

Movie – 100% Kobe Earthquake

18

Out-of-plane buckling of the braces

19

Out-of-plane buckling of the gusset plate

20

Hysteric responses of the braces

Brace axial deformations [in.]

-0.5 0 0.5-50

0

503rd story left brace

-0.5 0 0.5-50

0

50

-0.5 0 0.5-50

0

50

Bra

ce a

xial

forc

es [k

ips]

-0.5 0 0.5-50

0

50

-0.5 0 0.5-50

0

501st story left brace

-0.5 0 0.5-50

0

501st story right brace

3rd story right brace

2nd story left brace 2nd story right brace

21

Hysteric responses of the zipper columns

-0.06 -0.04 -0.02 0 0.02 0.04 0.06

-20

-10

0

10

20

3rd story zipper column

Axi

al fo

rce

[kip

s]

-0.06 -0.04 -0.02 0 0.02 0.04 0.06

-20

-10

0

10

20

2nd story zipper column

Axi

al fo

rce

[kip

s]

Axial deformations [in.]

22

Analytical verification – roof drift ratio

0 5 10 15-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

Time [sec]

Roo

f drif

t rat

io [%

]

ExperimentAnalytical

23

Analytical verification – brace axial forces

0 5 10 15-50

0

50

3rd story left brace

0 5 10 15-50

0

50

3rd story right brace

0 5 10 15-50

0

502nd story left brace

Bra

ce a

xial

forc

es [k

ips]

0 5 10 15-50

0

502nd story right brace

0 5 10 15-50

0

50

1st story left brace

Time [sec] 0 5 10 15

-50

0

50

1st story right brace

Time [sec]

ExperimentAnalytical

24

Analytical verification - ZC axial forces

0 5 10 15

-20

-10

0

10

20

3rd story zipper column

Axi

al fo

rces

[kip

s]

0 5 10 15

-20

-10

0

10

20

2nd story zipper column

Time [sec]

Axi

al fo

rces

[kip

s]

ExperimentAnalytical

ExperimentAnalytical

25

Movie – 200% Kobe Earthquake

26

Out-of-plane buckling of the braces

27

Geographically distributed test

University of California, Berkeley

University of Colorado, Boulder

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UC Berkeley

CU Boulder

Internet

Testing architecture (distributed test)

Simulation PC Real time PC Test PC

Simulation PC Real time PC Test PC

29

Input ground motions – Kobe (80% - 100%)

0 5 10 15 20 25-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

Time [sec]

Gro

und

acce

lera

tions

[g]

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Hysteric responses of the braces

-1 -0.5 0 0.5 1-50

0

503rd story left brace

-1 -0.5 0 0.5 1-50

0

503rd story right brace

-1 -0.5 0 0.5 1-50

0

502nd story left brace

Bra

ce a

xial

forc

es [k

ips]

-1 -0.5 0 0.5 1-50

0

502nd story right brace

-1 -0.5 0 0.5 1-50

0

501st story left brace

Brace axial deformation [in.]

-1 -0.5 0 0.5 1-50

0

501st story right brace

31

Hysteric responses of the zipper columns

-0.1 -0.08 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.08 0.1-50

0

50

3rd story zipper columnA

xial

For

ce [k

ips]

-0.1 -0.08 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.08 0.1-50

0

50

2nd story zipper column

Axi

al F

orce

[kip

s]

Axial deformation [in.]

32

SummaryConducted 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.

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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

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

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.