1. The 5th Tongji-UBC Symposium on Earthquake Engineering
“Facing Earthquake Challenges Together” May , Tongji University Shanghai, China
Ambient Vibration Tests and Model Updating of the Health Sciences Parkade at UBC
ILARIA CAPRARO
Supervisor: Dr. Carlos E. Ventura
MASc | University of Bologna, Italy (2012)
PhD Student | The University of British Columbia, Canada ( Present)

2. Outline Description of the Health Sciences Parkade;
Two different Ambient Vibration Tests:
Normal operational conditions;
Almost empty environment;
Modal frequencies and mode shapes evaluation;
Comparison between the results obtained with the two different tests;
Sensitivity analysis and modal updating;
Examples of seismic retrofits on the Parkade;
Conclusions and future work.

3. Description of the HSP Two 4-storey reinforced concrete buildings;
Sets of three ramps each level;
LFRS: shear walls and Moment Resisting Frame;
External shear walls introduce stiffness irregularity in elevation and “short column” effect.

4. Main Lateral Force Resisting System
External Shear Walls and
“Short Columns effect”
FE Models developed with SAP2000

5. Complete AVT -Setups Configuration-
9 wireless Tromino sensors;
GPS synchronization;
5 setups;
Operational conditions → high levels of traffic.
Recording duration: 40 mins;
Sampling frequency 256 Hz;
Reference Sensor

6. ARTeMIS Model

7. Frequency Domain Analysis
FDD: Frequency Domain Decomposition
Vertical channels not included in the analysis;
Re-sampling at 128 Hz;
1024 frequency lines;
Decimation: 0 – 32 Hz;
Six modes identified up to 8 Hz.
Time Domain Analysis
SSI-UPC: Stochastic Subspace Identification
Natural frequencies and modal damping values evaluated;
High values for modal damping;
← Stabilization diagram for Setup 4.

8. 1st Mode Shape: 2.756 Hz N – S Longitudinal

9. 2nd Mode Shape: 3.894 Hz Torsional

10. 3rd Mode Shape: 4.413 Hz E – W Transversal

11. 4th Mode Shape: 5.781 Hz Torsional

12. Summary of the Results Mode # Frequency [Hz] Comment FDD 1 2.756
1 st N-S Longitudinal 2
3.894
1 st Torsional 3
4.413
1 st E-W Transversal 4
5.781
2 nd Torsional 5
7.244
2 nd N-S Longitdinal 6
7.944
3 rd N-S Longitudinal

13. AVT in almost empty environment
Just the reference sensor used at the same location as previously;
Test performed late in the day;
Recording duration and sampling frequency same as the complete AVT.
Reference Sensor

14. Comparison between the two AVTs
1st natural frequency is ~ 12% higher when traffic is present;
Vertical component of vibration is predominant between Hz;
Strong amplification due to traffic load;
The change in mass between the two tests did not affect significantly the natural frequencies of the structure.

15. Sensitivity Analysis 6 Responses: Natural frequencies. 22 Parameters:
Rho: material density of slabs;
E: elastic Modulus of shear walls;
H: shear wall thickness.
Sensitivity Matrix, FEMtools V3.8 →

16. Model Updating Results
AVT
SAP2000
FEMtools updated
Description
Frequency [Hz]
Difference 1
2.756
2.58
6.3 %
2.68
2.7 %
1st N-S Longitudinal 2
3.875
3.56
8.1 %
4.15
7.2 %
1st Torsional 3
4.413
4.58
3.8 %
5.47
23.9 %
1st E-W Transversal 4
5.781
6.72
16.3 %
6.70
15.9 %
2nd Torsional 5
7.250
8.17
12.7 %
7.30
0.7 %
2nd N-S Longitudinal 6
7.931
7.98
8.03
1.2 %
3rd N-S Longitudinal

17. Conclusions and future work
1st natural frequency at Hz corresponding to a fundamental longitudinal mode in N-S direction;
The first torsional mode is about 1 Hz higher than the fundamental mode. The HSP is likely to experience both lateral and torsional responses;
Comparing the results from the two AVTs, the mass of the cars seems not to affect significanlty the dynamic properties of the HSP;
Strong amplification of vibrations due to traffic loads.
After model updating, general increase of E and H was observed;
The stairwells were proved to contribute significantly to the dynamic behaviour of the structures as their thickness increased of about 150%.
Little information on the contribution of the ramps to the dynamic behaviour of the HSP due to limited number of sensors.
AVT repeated in March 2015 after seismic retrofit.

18. ANY QUESTIONS?

19. Certificate of Structural
Thank you!
Certificate of Structural
Engineering Program