Coupled dynamic analysis and equivalent static wind loads on buildings with three-dimensional modes

Buildings with either complex geometric shapes or structural systems with noncoincident centers of mass and resistance, or both, may undergo three-dimensional (3D) coupled motions when exposed to spatiotemporally varying dynamic wind loads. To capture the dynamic load effects, this paper presents a framework for the analysis of 3D coupled dynamic response of buildings and modeling of the equivalent static wind loads (ESWLs). This framework takes into account the correlation among wind loads in principle directions and the intermodal coupling of modal response components. The wind loading input for this scheme may be derived either from multiple point synchronous scanning of pressures on building models or through high-frequency force balance (HFFB) measurements. The ESWL for a given peak response is expressed as a linear combination of the background and resonant loads, which respectively reflect the fluctuating wind load characteristics and inertial loads in fundamental modes of vibration. The nuances of utilizing HFFB measurements for buildings with 3D coupled mode shapes are elucidated with a focus on the evaluation of the generalized forces including mode shape corrections, the background and resonant responses, and the associated ESWLs. Utilizing a representative tall building with 3D mode shapes and closely spaced frequencies, the framework for the analysis of coupled dynamic load effects and modeling of 3D ESWLs is demonstrated.