Study On Wind-Induced Effects And Three-Dimensional Wind Load Combinations Of Square-Sectioned Super High-Rise Buildings With Structural Eccentricities

High-rise and super-high-rise buildings are typical wind-sensitive structures because of their high flexibility and small damping.Due to the consideration of lighting and ventilation,many buildings have asymmetric structural configurations,which usually lead to structural eccentricities,i.e.,eccentricities between the mass and stiffness centers.For high-rise buildings with structural eccentricities,their three-dimensional(3D)wind-induced responses are affected by both the modal-coupling and load-coupling,which significantly complicate the evaluation of 3D wind-induced responses and equivalent wind loads(ESWLs).The modal-coupling can greatly complicate the wind-induced vibrations of high-rise buildings with structural eccentricities,which brings differences to vortex-induced vibration(VIV)responses and aeroelastic effects of buildings with and without eccentricities.In addition,due to fluid-solid interaction effects,different structural vibration usually causes different flow field and wind loads over the structure.In other words,structural eccentricities affect the correlation between wind loads along different directions and their combinations.However,research on the 3D wind-induced effects and wind load combinations of high-rise buildings with structural eccentricities is inadequate.To comprehensively understand the influence of structural eccentricity on wind-induced effects and wind load combinations of high-rise buildings,based on the square-sectioned super high-rise building,this thesis conducted the following works:1.Based on structural dynamics theory,the contributions of modal-coupling and loadcoupling to 3D wind-induced responses of high-rise buildings with structural eccentricities are separately derived.Incorporated by the wind tunnel test data of rigid models,the influences of modal-coupling and load-coupling on 3D wind-induced responses are systematically analyzed.Furthermore,based on the equivalence of story internal forces,the ESWLs that can accurately reproduce the along-height-distribution of internal force responses of high-rise buildings with structural eccentricities are derived,and the influences of structural eccentricity on ESWLs of high-rise buildings are summarized.2.Seven multi-degree-of-freedom(MDOF)aeroelastic models of high-rise buildings with different structural eccentricities are designed and manufactured.Incorporated by the wind tunnel test data of aeroelastic models,the influences of structural eccentricity on the crosswind vortex-induced vibration of high-rise buildings are summarized,and the mechanism of structural eccentricity affecting the VIV of high-rise buildings is revealed with the help of numerical simulation technology.3.Based on the wind tunnel test data of the MDOF aeroelastic model,the crosswind vibration frequency and aerodynamic damping ratio of high-rise buildings with structural eccentricities at different wind speeds are identified using the stochastic subspace identification(SSI)method.Furthermore,the influences of structural eccentricity on the crosswind vibration frequency and aerodynamic damping ratio are analyzed.On this basis,an evaluation model of the vortex-induced resonance response of high-rise buildings with structural eccentricities considering the instantaneous vortex-induced shedding force in the crosswind is proposed,and the empirical formulae of relevant parameters are given.4.Two wind load combination methods that can be applied to high-rise buildings with structural eccentricities are proposed.They are based on(1)the extreme correlation of buildings’ wind-induced responses and(2)the response vector of buildings’ base shear stresses,respectively.Furthermore,the respective expressions of the two methods’ 3D wind load combination coefficients are given.The results of 3D wind load combination coefficients for buildings with different structural eccentricities are calculated,and the influences of structural eccentricity on buildings’ wind load combination coefficients are summarized.