1. Model Updating of a Nine-Story Concrete Core Wall Building
The 5th Tongji-UBC Symposium on Earthquake Engineering
“Facing Earthquake Challenges Together” May , Tongji University Shanghai, China
Model Updating of a Nine-Story Concrete Core Wall Building
STEVE MCDONALD
[Dr. Carlos Ventura]
BASc | University of British Columbia, Canada (2012)
MASc Student | The University of British Columbia, Canada ( Present)

2. Outline Background & description of structure Vibration tests
Finite element model
Model updating
Results and summary

3. Description of Structure

4. Description of Structure
Constructed in 1963
Nine stories including recently added penthouse
Reinforced concrete with steel-framed penthouse
Slabs supported by concrete columns and core walls
Connected to five-story classroom block

5. Description of Structure
Typical floor plan 30.5 m by 16 m.
Story height approximately 2.7 m.

6. Ambient Vib. Test Results
Ten modes identified
Mode
Period (s)
Freq. (Hz)
Description 1
1.14
0.88
Site period 2
0.39
2.56
1st lateral 3
0.36
2.81
1st longitudinal 4
0.31
3.25
1st torsional 5
0.22
4.50
Coupled torsional-translational 6
0.17
5.75 7
0.14
7.38
2nd longitudinal 8
0.11
9.00
2nd torsional 9
0.09
11.00
2nd lateral 10
0.07
14.13
3rd longitudinal

7. Finite Element Model

8. Finite Element Model Modelled concrete walls in west end
Rest of block modelled as single column at centre of geometry
Rigid beams used to connect column to embedded walls
Material properties:
Elastic, uncracked
Estimated lower-bound compressive strength of 34.5 MPa for concrete
Elements:
Columns and beams as elastic frames
Walls and slabs as quad shells
Architectural mullions as trusses

9. Finite Element Model

10. Response Selection Responses chosen as target for model calibration
Mode shapes from FEM paired with AVT results using FEMTools
Response quantities: frequencies and mode shapes

11. Sensitivity Analysis Structure separated into six groups:
Beams and columns
Elevator core walls
Shear walls
Classroom block “column”
Rigid beams from classroom block
Beams between embedded walls and tower

12. Sensitivity Analysis Properties of each group analyzed for sensitivity
Software: FEMTools

13. Sensitivity Analysis Most sensitive groups:
Classroom block column
Rigid beam connections
Significant because of assumptions made modelling these groups

14. Parameter Selection Seven parameters chosen: Modulus of elasticity
Mass density
Cross sectional area
Shear stiffness area
Moment of inertia about x, y, and z
Shell thickness
Poisson’s ratio

15. Results Average freq. difference of 32% reduced to 1.0%
Average MAC of about 70% for paired modes
Mode
Description
FT Results (Initial)
Freq. (Hz)
AVT Results
Difference (%)
FT Results (Updated) 2
1st lateral
3.05
2.56
18.99
-0.13 3
1st longitudinal
4.42
2.81
57.11
2.84
0.95 5
torsional
8.16
4.50
81.28
4.49
-0.25 7
2nd longitudinal
8.87
7.38
20.23
7.35
-0.37 8
2nd torsional
12.42
9.00
37.96
8.93
-0.81 9
2nd lateral
13.56
11.00
23.23
11.72
6.51 10
3rd longitudinal
10.08
14.13
-28.66
14.25
0.85

16. Summary Office tower tested and modelled in SAP2000
Model calibrated in FEMTools by varying seven parameters
Close correlation with seven mode shapes
Average frequency error of 1%

17. Proposed Seismic Retrofit

18. Thank you!