Study Of Wind-induced Responses Of Slender High-Rise Buildings Considering Lateral-torsional Aspect

Wind load is the main lateral effect on slender high-rise buildings. Although the traditional simplified wind-induced dynamic analysis based on the rigid floor assumption and the storey-to-storey stiffness assumption can be carried out with computational efficiency, the errors involved would be noticeable. It is essential to explore a simplified analysis method which is not only highly efficient but also contains characteristic for good reflection of complex wind vibration mechanisms of slender high-rise buildings.In this paper, a residential high-rise steel building structure with a height of100m around located at the coastal region of China is taken as an engineering case. The wind-load time histories of the building surface under different wind angles have been measured by means of the wind tunnel model test. Three-dimensional wind-induced dynamic responses are determined using the refined finite element model, simplified rigid floor model and the load-code approach. The interference effect of the typical building located in the centre of the building community is then carried out. The main contents of the paper are as follows:1. Based on the refined finite element model, the first three mode shapes and frequencies in different moving directions are analyzed, and the algorithm for finding the wind nodal loads and the procedure for conducting the dynamic time history analysis are presented. Then the variation characteristics of peak displacement and peak acceleration responses with respect to the wind angle are studied. The effects of different opening locations and opening ratios on natural frequencies and wind-induced vibrations of the structure are then examined.2. Based on the two simplified rigid floor models:the shear floor model and the bending-shear floor model, the results containing natural frequency and wind-induced responses are compared with those of the refined finite element model and the load-code approach.3. Considering the interference effects of surrounding high-rise buildings, the interference effects of the surface pressure, the floor wind force amplitude and the power spectrum of floor force are discussed. Then the displacement and acceleration responses of the structure are determined in the interference condition, and the variations of wind interference factors with respect to the wind angles are analyzed.The available analysis results confirm that each order of the structural frequencies obtained using the overall structural stiffness-based bending-shear floor model contains very small calculation errors compared with the refined model. However, only the first-order translational and torsional frequencies can be found with high accuracy if the traditional shear floor model based on the storey-to-storey stiffness assumption has been employed. The wind dynamic displacements calculated by the bending-shear floor model are more accurate than those by the shear floor model not only in their amplitudes but also in the unfavorable wind direction angles among them. The acceleration responses by the bending-shear floor model are slightly larger than those of the refined model, leading to a safety condition, but the results using the shear layer model would be smaller than the refined model under some wind direction angles, and furthermore different unfavorable wind direction angles might be gained. The translational displacements calculated by the current load code approach are overall in a safety condition, but the obtained torsional displacements may be in an unsafe situation.