Field dynamic test and Bayesian modal identification of a special structure - the Palms Together Dagoba

Abstract

The Palms Together Dagoba at Famen Temple is a 12-story steel-reinforced concrete building, which comprises a vertical inversion and setback tubes with two inflection points formed along its height. It contains two towers with the first two and the top two floors connected, while the remaining floors are separated forming an irregular configuration. During its construction, an earthquake of 8.0 magnitude struck about 500 km away. The seismic intensity at the site is reported to be 6, which may result in some cracks for the local structures. This paper presents the work on field test 1 month after the earthquake and modal identification of the Dagoba. To determine the dynamic characteristics of this structure, ambient vibration tests were performed. Four setups were designed to cover all the degrees of freedom of interest involving the floors from the ground to the roof. A recently developed Bayesian method incorporating multi-setups was employed to identify the modal properties by using the data in all the setups simultaneously. In addition to the most probable values, the associated posterior uncertainties were also obtained, providing an estimation tool to assess the accuracy of the modal parameters. These results were utilized to investigate the modal properties of this structure. The influence due to the earthquake was also studied based on the observation in the field. Before the full-scale field tests, shaking table tests were also implemented. The dynamic properties from the two different tests, as well as their posterior uncertainties, were compared and discussed in the paper.

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