Structural coupling and wind-induced response of twin tall buildings with a skybridge
Date
2008
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Abstract
Twin tall buildings with a connecting skybridge involve two types of coupling: the structural coupling, developed by a skybridge and synchronizing the motions of vibration of the two building and the aerodynamic coupling resulting from high cross-correlations of the components of wind loading. The physical understanding of these couplings and their impacts on the wind-induced response of the buildings are not fully understood, when using a high-frequency force balance (HFFB) approach tailored for single tall buildings. Detailed laboratory mapping of the aerodynamic loading and coupling requires specialized experimental techniques. Predictions of the response of the structurally coupled buildings, due to correlated wind loading, involve utilization of advanced dynamic analysis. This dissertation addresses the issues associated with correlated wind loading and structurally coupled response of twin buildings with a skybridge. Wind tunnel testing to acquire the correlated wind loading on twin buildings is described. The effects of the relative positions of the buildings on the loading correlations and coherences are discussed. These results are next used as an input to an analytical model developed to calculate the building wind-induced response. The building system, including the structural coupling, is represented by a six-degree-of-freedom model lumped at the skybridge level. In free vibration, the natural frequencies and modal shapes are obtained for various levels of the relative stiffness of the (inter-building) beam representing the skybridge. The model is subsequently used to investigate the effects of aerodynamic and structural couplings on the roof top accelerations of the buildings. Spectral integration and white-noise approximation approaches are employed in calculations of the building responses. The presented results show significant effects of both the aerodynamic and structural couplings. Simplified empirical relations for application in preliminary design of structurally connected tall buildings are proposed. Recommendations for follow-up studies of coupled wind-induced response of tall twin buildings are discussed.
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Subject
skybridge
structural coupling
tall buildings
twin tall buildings
wind engineering
wind-induced
civil engineering