| Recently,with the rapid development of advanced construction technology and highperformance building materials,the new generation of super-tall buildings are becoming higher,softer,lighter,meanwhile their dampings are lower.When the natural frequency or even higher-order modal frequencies of the super-tall building is located near the main frequency of the strong wind dynamic load,the wind-induced response of the structure will increase significantly.At this time,the structure movement will significantly affect the characteristics of the surrounding wind field,resulting in the nonlinear aeroelastic effect with self-excitation characteristics.Therefore,it is urgent to establish a windresistant design method and a wind-induced analysis theory of the high-rise building considering fluid-structure interaction.At present,domestic and oversea structural engineers have accumulated some practical experience in the wind resistant design of high-rise buildings.However,due to the lack of relevant regulations on the aeroelastic effect of high-rise buildings in the existing wind resistant design codes,the fluid-structure interaction of high-rise buildings is seldom considered in engineering practice,which is mainly due to the lack of efficient and reliable fluid-structure interaction analysis method for wind-induced response of high-rise buildings.Therefore,it is necessary and urgent to study the wind-induced response mechanism of high-rise buildings considering the fluidstructure interaction.The main research work and conclusions of this paper include:(1)In order to obtain a proper numerical simulation method applicable to the study of the acrosswind vortex-induced vibration of rectangular prism,and to discuss the phenomenon and mechanism of vortex induced vibration,this paper takes a rectangular prism with the side ratio of 1:1.5 as the research object.Firstly,the accuracy of the numerical simulation method for the static flow around a bluff body structure is verified by the wind tunnel test results.Then,combined with the results of the aeroelastic wind tunnel test,URANS(Unsteady Reynolds averaged Navier Stokes equations)method is used in the 2D simulation to evaluate the effects of two dynamic response methods(Newmark-β method,the fourth-order Runge Kutta method)and three CFD solution settings on the accuracy and effectiveness of simulation.The results show that the displacement response obtained by Newmark-β method and suitable solution setting is in good agreement with the wind tunnel test,but some results(such as kurtosis)obtained in the wind tunnel test cannot be reproduced.Then,due to the 2.5D simulation can take into account the vortex shedding correlation of each section along the model which is ignored in 2D simulation,the results of 2D simulation and 2.5D large eddy simulation is compared.The results show that the 2.5D large eddy simulation can reproduce the process of various parameters(such as probability distribution of displacement response,kurtosis,peak factor,etc.)changing with reduced wind velocity in wind tunnel test,which provides an important reference and technical guide for the follow-up study of the numerical simulation of acrosswind vortex induced vibration of rectangular bluff body structure.(2)In order to obtain a proper two-way coupled fluid-structure interaction numerical simulation method for the study of vortex-induced vibration of high-rise building,and to discuss the phenomenon and mechanism when vortex induced vibration occurs,this paper uses the high-rise building benchmark model,CAARC standard high-rise building model as the research object.Based on the large eddy simulation method,three different twoway coupled fluid-structure interaction methods(Equivalent lumped mass system method,free-form deformation method,mapping weighting method in ANSYS system coupling component)are used for the two-way coupled fluid-structure interaction numerical simulation.Combined with the aeroelastic results of wind tunnel test,the accuracy and efficiency of all three methods are compared.The results show that the equivalent lumped mass system method can retain most of the dynamic characteristics of high-rise buildings(natural frequency,damping ratio,mass,etc.)after the model is simplified,and can capture the phenomenon of displacement response increasing significantly and "lockin" near the critical wind speed,thus achieving the balance of accuracy and efficiency.Then,the equivalent lumped mass system method and large eddy simulation method are used in the further study of the mechanism of alongwind and acrosswind wind-induced vibration of an isolated high-rise building.The results show that when vortex-induced resonance of CAARC standard high-rise building occurs,the acrosswind load correlation between different layers have increased overall,and the layer range with a correlation coefficient greater than 0.8 with the top layer has a significant increase.In the frequency domain,the acrosswind load coherence between different layers have significantly increased and been in phase in the corresponding frequency range of “lockin”phenomenon.It is proved that the main reason of vortex-induced resonance is the vortex force produced by the vortex with the shedding frequency close to the natural frequency of the model.At the same time,the increase of correlation and coherence of wind load between different layers loads caused by resonance will intensify the response of the structure vortex induced resonance,and the self excitation characteristics are significant.(3)In order to verify the feasibility of the two-way coupled fluid-structure interaction numerical simulation method in the study of vortex-induced vibration of super-tall buildings,and to research the influence of aerodynamic shape optimization on vortex-induced vibration of super-tall building,this paper takes a super-tall buildings with aerodynamic shape optimization as the research object.Combined with wind tunnel test and field measurement,the large eddy simulation method and the equivalent lumped mass system method verified in this paper are used in rigid and two-way coupled fluid-structure interaction simulation of an actual super high-rise building with aerodynamic optimization.Furthermore,the vortex induced vibration response of the super high-rise building at higher wind velocity which cannot be involved in the wind tunnel test is also simulated.The results of rigid model simulation show that base load obtained by the numerical simulation method is close to the results of wind tunnel test.Considering that the wind tunnel test is limited by the similarity criterion,the size of wind tunnel and the maximum wind velocity,numerical simulation can become an important approach to evaluate the aerodynamic and aeroelastic effects of higher and softer high-rise buildings in the future.The aeroelastic results show that the response results of the acceleration and displacement of the super-tall building under different reduced wind speeds are close to the wind tunnel test and field measurement results.But the alongwind responses calculated by the wind tunnel test results are conservative,while the acrosswind responses are not accurate.After aerodynamic shape optimization,super-tall buildings can effectively reduce the acrosswind load correlation between different layers compared with square section super-tall buildings,so that the vortex shedding processes of cross sections at different heights are in different stages,which mean they are out of phase.From the point of load spectrum,the acrosswind base moment spectrum is a broadband spectrum,and the frequencies corresponding to the peak value of acrosswind load spectrum of different layers are different.A two-way coupled fluid-structure interaction numerical simulation method based on the equivalent lumped mass system method and large eddy simulation method is established in this paper,which provides an important reference and technical guide for the follow-up numerical simulation of vortex-induced vibration of super high-rise buildings. |
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