Model Updating of a Nine-Story Concrete Core Wall Building The 5th Tongji-UBC Symposium on Earthquake Engineering “Facing Earthquake Challenges Together” May 4-8 2015, 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 (2013 - Present)

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

Description of Structure

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

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

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

Finite Element Model

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

Finite Element Model

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

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

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

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

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

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

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%

Proposed Seismic Retrofit

Thank you!