CFD Numerical Simulation On Aero-hydro Dynamic Loading And Wind-induced Response Of Tall Building With Supplementary TLD System

Tall buildings,which are characterized by their large aspect ratio,lightweight and low damping,are prone to excessive displacement or acceleration responses at the top of the buildings under the influence of strong/typhoon winds,thus are significantly affected from the structural safety and occupant comfort.To mitigate wind-induced responses of tall buildings,TLD(Tuned Liquid Damper)passive control systems have been widely employed in the windinduced vibration control of tall buildings in recent years,tall buildings with supplementary TLD system have therefore become the common configuration.Evaluation of wind-induced response of tall buildings with supplementary TLD system can be conducted from the field measurement and real-time hybrid simulation test methods.However,these methods are generally time-consuming and resource-intensive,resulting in high time and economic costs.Furthermore,the equivalent TMD(Turned Mass Damper)analysis method adopted the assumption of linear damping in TLD system,making it only applicable for linear sloshing under small-amplitude excitation.The analytical solutions for the nonlinear sloshing under large-amplitude excitations are challenging to be obtained.To evaluate and analyze the windinduced response of tall building with supplementary TLD system in a more cost-effective and reliable manner,a comprehensive study on the numerical CFD(Computational Fluid Dynamic)simulation was conducted by the open-source system OpenFOAM.The aerodynamic loading on the surface of tall building and hydrodynamic loading from the liquid sloshing in the TLD system,as well as the wind-induced response of tall building with supplementary TLD system were investigated comprehensively in this dissertation.The main work can be divided into the following parts:(1)Taking a square-sectioned tall building with the aspect ratio of 4:1:1 as the research object,the wind tunnel tests with simultaneous overall loads testing from local pressure measurements were conducted on the rigid tall building model in the atmospheric boundary layer wind tunnel with open and suburban terrains.The wind pressure on the surface of the building and the layer aerodynamic loading integrated at the specified floor levels were obtained.The effects of turbulence intensity on the base moment,wind pressure coefficient and the aerodynamic wind loading at the specified floor levels are investigated.(2)Three turbulent velocity synthesis methods adopted in the generation of velocity inlet in large eddy simulation,which include the linear filtering method,vortex method and DSRFG(Discretizing and synthesis Random Flow Generation)method,are respectively studied by developing the CFD open source platform OpenFOAM in this dissertation.Comparing with the results from wind tunnel tests,the inflow characteristics of these three methods for generating fluctuating winds are investigated.The surface aerodynamic wind loading of the same tall building model are simulated.It is clarified that the numerical simulation performance from the DSRFG method is the best among these three methods.(3)On the basis of the DSRFG turbulence generation method,the numerical algorithm from the proposed Synthetic Volume Forcing(SVF)is developed by adding the volume force in the computational domain in the large eddy simulation of wind velocity and pressure fields within the OpenFOAM.This treatment was achieved by adding the source terms to the momentum equation in numerical CFD simulation algorithm.The concept of Turbulence Intensity Amplification Factor(TIAF)is proposed to compensate for the attenuation of turbulence intensity at the target position.The combined TIAF-SVF algorithm was then adopted to simulate the surface wind pressure and aerodynamic wind loading at the specific floor levels of the studied building.It is shown that the proposed TIAF-SVF algorithm can accurately simulate the aerodynamic loading on the rigid model.Moreover,further simulations are conducted to evaluate the aerodynamic loading on the aeroelastic model,the tip displacement response of the tall building is initially estimated as well.(4)The hydrodynamic loading of liquid sloshing in the TLD system is simulated and analyzed to numerically simulate the control force of the TLD system with high accuracy.Taking the third-generation benchmark tall building model for wind-induced vibration control study as an example,three CFD/CSD coupling algorithms considering the tall building-TLD system coupling effect have been developed.By combining the simultaneous time-domain dynamics analysis on the main structure with the numerical simulation of liquid sloshing in TLD system within the OpenFOAM CFD environment,the wind-induced vibration control effect of TLD system was numerically evaluated.The tip acceleration,displacement,and velocity responses of the main structure as applied to the external excitation of the TLD system,respectively.It is found that the developed CFD/CSD coupling algorithm,which introduces the source terms into the momentum equation with the tip acceleration excitation,demonstrates the highest simulation accuracy among the three coupling algorithms.Compared with the results from the existing real-time hybrid simulation results,the relative errors in CSD/CFD coupling simulation results are sufficiently small to satisfy the simulation needs.(5)Taking the third-generation benchmark model for wind-induced vibration control study as an example,the machine learning algorithm is adopted to construct a dynamic reduced order model(ROM)for the CFD simulation of the liquid sloshing process in the TLD system.Combined with the time-domain dynamics analysis of the main structure,the dynamic ROM/CSD coupling algorithm is proposed in this dissertation.Moreover,the dynamic ROM that integrates tall building with supplementary TLD system as a unified entity is further developed,facilitating rapid assessment of wind-induced vibration responses under unknown loading conditions.Comparison with the results from real-time hybrid simulation and CFD/CSD coupling algorithm,the proposed dynamic ROM/CSD coupling algorithm in this study could exhibits high accuracy in numerical prediction on wind-induced responses on the tall buildings with supplementary TLD system.Additionally,the computation time for simulating the wind-induced response of tall building with supplementary TLD system can be achieved within a few seconds,significantly reducing the required simulation time.