The Wind Effect And Wind-induced Vibration Control Of Typical Super-tall Buidling

With the progress of economization and urbanization, high-rise buildings have been growing rapidly. The application of innovative structural systems and high strength materials makes modern tall buildings more flexible and lightly damped and, at the same time, greatly reduces the weight of the building. The wind load of the structure induced by the strong wind is the dominant loading that affects the structural safety and serviceability. The wind loads and its induced response of the super tall building are the primary concern in the design. Previous investigations show that the across-wind induced response of the high buildings which are more than 200 meters will eventually exceed the along-wind response and become the controlling wind direction in design. Based on the information of the two super tall buildings which are more than 430m height in south China(Guangzhou West Tower(432m) and Shenzhen Kingkey Finance Center(439m)), a systematic study covering four aspects has been performed to determine the characteristics of the wind loads and the wind effects of the typical super tall building.1. An efficient algorithm named as harmonic excitation method (HEM) is employed to calculate the wind-induced response of complex space structures by synchronous multi-pressure measurement on rigid model in the boundary layer wind tunnel. The method has the same accuracy as, but much faster and lesser memory consumption than the traditional complete quadratic combination (CQC) approach. On the basis of the wind-induced response accurately analyzed by the HEM approach, the load-response-correlation (LRC) approach is applied to estimate the equivalent static wind load (ESWL) on structures with the wind-induced response (including the resonant response) and modal correlation. A complex stadium roof structure is analyzed to illustrate the effectiveness of the proposed method.2. The aerodynamic wind loads on the GWT are studied in details, and on basis of this study, The cross-power spectra densities of the aerodynamic force, which are calculated by the coherence function method (CFM) with empirical exponential decay coherence function, are used as substitutes of the off-diagonal elements of the power spectra density matrix of the aerodynamic force. The effects of the CFM error on the calculation of the wind-induced response of super-tall building are analyzed. The results show that the results of CFM agrees well with the accurate solution in the along-wind direction when the exponential decay factor in the empirical exponential expression of coherence function is ranging from 6 to 8. Significant difference, however, is found in the across-wind direction in this case. The effects of the participant mode number on the calculation of wind-induced structural response are further investigated. Difference is found in the along-wind response when higher order mode is neglected, resulting in a maximum error of 9% in the calculation of inter-story displacement angle. However, wind induced response in the across-wind direction is still dominated by the fundamental mode. Finally, feasible methods for estimation of across-wind response of tall building are discussed and proposed.3. MDOF aero-elastic model technique is used to study the wind induced aeroelastic effects on the KFC. The Random Decrement Technology (RDT) is applied to identify the building's aerodynamic damping. The results show that the aerodynamic damping of KFC is positive at all of the tested wind speed which covers a great range of return periods and the aerodynamic damping increase with the increase of the wind speed. Significant effect of the wind induced vibration on the aerodynamic wind load haven't found in the tested wind speed also.4. Base on the HEM, an effective algorithm is proposed for the calculation of wind-induced vibration of super-tall buildings using Tuned Mass Damper (TMD) for the data processing by synchronous multi-pressure measurement on rigid model in the boundary layer wind tunnel. This method can accurately analyze the effectiveness of TMD in suppressing wind-induced response of complex space structures. Based on the super tall building-KFC (439m), optimization of the parameters of STMD is firstly performed. Subsequently wind-induced vibration control effect using MTMD is studied. The results show that the proposed algorithm is correct and effective. The maximum reduction of cross-wind dynamic responses using STMD is about 30% comparing to that without TMD. The effectiveness of MTMD with different parameters is superior to that of STMD in controlling wind-induced response. Suppressing the response caused by higher modes will increase that by lower modes.5. For verifying theoretical analysis result and the really effect of suppressing wind-induced vibration of KFC with TMD, a TMD device arranged in the top-level of the above mentioned MDOF aero-elastic model of KFC is used for suppressing cross-wind response. The effect of TMD with different parameters in suppressing wind-induced response is researched. The results show that the maximum reduction of cross-wind dynamic responses is achieved when the frequency of TMD is close to the 2nd order natural frequency of the structure. The acceleration response in the top-level of the structure reduces significantly with the increase of damping ratio of TMD, and contrarily amplifys when the TMD damping ratio is less than 0.7%.6. The total base moment and the equivalent lateral stiffness of the structure are set as optimization objectives, while the peak displacement and peak acceleration in the top-level of the structure are served as constraints. Combining with the pressure by synchronous multi-pressure measurement on rigid model in the boundary layer wind tunnel, structural optimization is conducted with different optimization goals. The results show that a reduction of 15% of total base moment can be achieved if the moment is served as the optimization objective function, while if the total equivalent lateral stiffness is served as the optimization objective function with the top peak acceleration as a constraint, the equivalent total lateral stiffness is less than designed result.