Dynamic response measurements from natural excitation were carried out for a 18-story office building(SIB) to determine its inherent properties. A steel beam-column frame system was adopted as a typical structural form, but a concrete core wall was added to resist the lateral force more effectively, resulting in a mixed configuration. The most advanced operational system identification methods based on frequency- and time-domain like FDD, pLSCF and SSI were used to extract modal parameters form a series of vibration records. The frequencies and mode shapes extracted from different identification methods showed a greater consistency, however the three lower frequencies exhibited 1.1 to 1.6 times as stiff as those obtained using a detailed 3D-FE model. Automatic FE model updating adopting optimization theory was applied to correlate experimental and analytical modal parameters such as natural frequencies and mode shapes. The simplified FE model containing 3 stiffnesses and 3 masses at each story as structural parameters derived from a detailed 3D-FE model was used as a starting one for updating. The excellent match between test and analytical modal parameters was made for the lower three modes out of the six. Based on the updating results, it can be judged that the domestic design practice for FE analysis somewhat underestimates the story stiffness, while overestimating the story mass.
Dynamic response measurements from natural excitation were carried out for a 18-story office building(SIB) to determine its inherent properties. A steel beam-column frame system was adopted as a typical structural form, but a concrete core wall was added to resist the lateral force more effectively, resulting in a mixed configuration. The most advanced operational system identification methods based on frequency- and time-domain like FDD, pLSCF and SSI were used to extract modal parameters form a series of vibration records. The frequencies and mode shapes extracted from different identification methods showed a greater consistency, however the three lower frequencies exhibited 1.1 to 1.6 times as stiff as those obtained using a detailed 3D-FE model. Automatic FE model updating adopting optimization theory was applied to correlate experimental and analytical modal parameters such as natural frequencies and mode shapes. The simplified FE model containing 3 stiffnesses and 3 masses at each story as structural parameters derived from a detailed 3D-FE model was used as a starting one for updating. The excellent match between test and analytical modal parameters was made for the lower three modes out of the six. Based on the updating results, it can be judged that the domestic design practice for FE analysis somewhat underestimates the story stiffness, while overestimating the story mass.
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