Experimental and numerical dynamic identification in an RC tower
Keywords:Ambient vibration survey, operational modal analysis, tower, system identification, mode shape.
In this study, the dynamic behavior of one of the prominent structures in Istanbul, Üsküdar Observation Tower (UOT) has been investigated. The structural system of the tower is formed by a reinforced concrete circular tube having 2.8 meters outside diameter with a 40 centimeter thickness. By referring to the ground level, it starts from -18.2 meter due to five basement stories around the tower and its height is 44 meters. Two reinforced concrete floors were partially hanged over at 36 meter and 40 meter in height. The tower has an independent structural system from the ground level but a non-structural cladding assembly connects it to an adjacent building in the complex. With the mentioned structural features, Ambient Vibration Survey (AVS) was utilized to obtain the dynamic characteristics of UOT by Peak Picking (PP) method. The obtained dynamic properties were discussed with the peculiarities of UOT. While the performed analysis revealed the ineffectiveness of the adjacent building and the underground stories in the dynamic behavior of UOT, the torsion action of the floors has been noted. A numerical model has also been constructed to obtain the dynamic characteristics of UOT by Finite Element Analysis (FEA). The model calibration required to increase the code-based modulus of elasticity of the concrete by 23% for pairing the experimental and numerical dynamic properties. The reasons of the increase and the correlation between AVS and FEA were discussed.
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