Applications in Civil Engineering

Automated Model Updating using Ambient Vibration Data from a 48-Storey Building in Vancouver

One of the purposes of conducting ambient vibrations tests on large civil engineering structures is to use the modal information obtained from these tests to improve the finite element model of the structure being investigated.

The building considered in this study is called Heritage Court Tower (HCT) and it is located in downtown Vancouver, British Columbia in Canada. It is a relatively regular 15-story reinforced concrete shear core building. In plan, the building is essentially rectangular in shape with only small projections and setbacks. Typical floor dimensions of the upper floors are about 25 m by 31 m. (see figure 1).

Figure 1: View of HCT building and typical floor plan dimensions (m).

The modal identification from a series of ambient vibration tests was performed using the ARTeMIS Extractor software.
For more information see http://www.svibs.com/documentation/case_hct.htm

A finite element model of the HCT building was made and solved with FEMtools. FEA. Properties of the beams, columns, shear walls, floor slabs and cladding panels were estimated and used to compute the first 6 modes of the building. These modes are then overlaid and compared with the experimentally obtained mode shapes. Figure 2 shows the result for the first 3 modes by reducing the FE model to the same number of degrees of freedom as used in the test model. This provides easier graphical interpretation of the results.

Figure 2: Comparison of reduced FE mode shapes of updated model and experimental mode shapes of HCT building.

Considering the uncertainty on the initial estimates of the input data, a number of parameters were selected to update the finite element model, including Young's modulus, mass density, moment of inertia and panel thickness of various components. The resulting improvement of mode shape correlation is shown in figure 3.

Figure 3: MAC matrices for six mode shapes of HCT building before (left) and after (right) model updating.

This case study showed that is it possible to accomplish an effective model updating of a large civil engineering structure using the results from ambient vibration. The use of FEMtools Model Updating greatly facilitates determining, which are the model parameters that can be modified in order to achieve a good correlation between experimental and analytical results. The interpretation of the changes obtained by the modal updating program requires knowledge of background information on the test and FE modeling assumptions.

For more information:

J.-F. Lord, Carlos E. Ventura, Eddy Dascotte, Automated Model Updating using Ambient Vibration Data from a 48-Storey Building in Vancouver. Proceedings of the 22th International Modal Analysis Conference (IMAC), January 2004, Detroit, Michigan.
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J.-F. Lord, Carlos E. Ventura, Eddy Dascotte, Rune Brincker, and Palle Andersen, FEM Updating using Ambient Vibration Data from an 48-Storey Building in Vancouver, British Columbia, Canada. Presented at the 32nd International Congress and Exposition on Noise Control Engineering (Internoise 2003), August 25.28, South Korea.
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Carlos E. Ventura, J.-F. Lord and Robert D. Simpson, Effective Use Of Ambient Vibration Measurements For Modal Updating Of A 48 Storey Building In Vancouver, Proceedings of the 3rd International Conference on Structural Dynamics Modeling - Test, Analysis, Correlation and Validation - Madeira Island, Portugal, June 2002.
Download (PDF, 280 KB)

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