Research On Field Measurement And Wind Tunnel Test Of Wind Effects On High-rise Buildings Under Typhoon

High-rise buildings are usually characterized by their height and flexibility.Therefore,they are more sensitive to the wind,and wind load becomes the critical load for horizontal deformation.As the building height is increased rapidly,more data such as wind field,wind pressure and the structural acceleration response of the building are needed.However,studies based on the simultaneous measurement of these data are quite limited,and the acceleration measured points are mainly placed on the top floor of the measured building.Moreover,extensive comparison between the wind pressures obtained from wind tunnel test and full scale measurement should be conducted to deepen the understanding of the wind effects on high-rise buildings.After upating the finite element model based on the modal information abtained from field measurement,the calculated results from the finite element model can be much more reliable and precise.Furthermore,elevator is the most important transportation equipment;their response during typhoon is directly affecting the safty of the passengers in it.However,there is no study on this field in China.The typhoon effect on elevators in high-rise building is also a big issue need to be investigated.Therefore,it is necessary to carry out some researches on the problems mentioned above,which is useful and meaningful for the wind resistance design of high-rise buildings.In this paper,field measurement has been conducted on a 168-meter building in Wenzhou during typhoon,by which significant field data are obtained,including wind field property atop the building,wind pressures on the surface of the 25 th floor,and the horizontal vibration acceleration response of five floors and the elevator car.And wind field property parameters of the building under the following typhoons are statistically analyzed,typhoon Soulik,Trami,Fitow,Matmo,Fung-wong,Chan-hom and Dujuan.When mean wind directions are within 67.5° to 135°,the following rules are verified,turbulence intensity and gust factor decrease as mean wind speed increases under typhoons,the turbulence integral length scale increases as mean wind speed increases under typhoons,and the Karman spectrum is applicable for describing wind speed spectrum of fluctuating wind in this region.Furthermore,the change rule that turbulence intensity and gust factor tend to be stable as mean wind speed increases when mean wind speed exceeds 10m/s is obtained.When mean wind direction is within 80.13° to 92.41°,thirty-two 10-min wind pressure samples during typhoon Fitow are selected,and mean wind pressure coefficients,fluctuating wind pressure coefficients as well as peak wind pressure coefficients of measured points are statistically analyzed.Then the longitudinal shape coefficients of the measured floor are calculated and compared with the standard value in Chinese Code,which indicates that the terrain type of the building location is close to the urban terrain(Category C in Chinese code).After that,a comparative study of the PSD of the fluctuating wind pressure and the fluctuating wind speed is conducted,and the applicability of the quasi steady theory to along wind direction is verified.Moreover,the aerodynamic admittance functions of the thirty-two samples are summarized,and on this basis,the index in Kawai equation is modified.Based on the analysis of coherence function between measured points,different generative mechanism of wind pressures in windward,leeward and sideward facades are systematically verified.The probability distribution characteristics of fluctuating wind pressures is analyzed,and the peak factor is calculated when target probability is 99.38%.The results show that the maximum peak factor in sideward side is 4.931,which illustrates that wind pressures of measured points within this area have strong non-Gaussian characteristics.Based on the measured acceleration response data obtained from multi-floors of high-rise building during typhoon Fung-wong,Chan-hom and Dujuan,variations of wind-induced acceleration responses with mean wind speed and mean wind direction are disclosed,which proves that root mean square of acceleration response and peak acceleration increase obviously as mean wind speed increases,while it is less affected by mean wind direction.Besides,the probability density distribution of 10-min measured acceleration response sample is proved to be basically consistent with Gaussian distribution in the sight of peak factors,which can provide theoretical reference for the prediction of acceleration response in design phase.Peak-picking method is adopted in this paper to identify modal parameters of measured acceleration data of the high-rise building,and the relationship between the 1st mode damping ratio and acceleration response amplitude is analyzed using random decrement technique(RDT).Meanwhile,the modal parameters of measured acceleration data are also identified by eigensystem realization algorithm(ERA)method,by which 3D finite analysis model is further modified,and thus the calculation accuracy of wind-induced response is improved greatly.Based on the data obtained from wind tunnel test for the high-rise building in Wenzhou,the influences of surrounding disturbance of the building on wind pressure coefficients are investigated.The bending moment coefficients of wind pressure measurement model are calculated,and the variation rule of wind pressure coefficient with height is studied,which is obtained in urban terrain without taking surrounding disturbance into consideration.Then local shape distribution coefficients of model measured points on the 25 th floor are studied.The probability distribution characteristics of fluctuating wind pressure are evaluated,and the de-clustering generalized Pareto distribution(GPD)method for small size samples is proposed.Comparative study of wind pressures obtained from wind tunnel test and measured wind pressure data are conducted on value and frequency domain,the comparison results showed that,the wind tunnel test results,including the variation rules of mean wind pressure coefficient,fluctuating wind pressure coefficient,shape coefficient,fluctuating wind pressure spectrum,and aerodynamic admittance functions are basically consistent with those obtained from field measurement,by which wind tunnel test technology is verified and improved.Furthermore,the wind pressure data obtained in the wind tunnel test is applied on the finite element 3-dimensional model to conduct time domain analysis for wind-induced responses of high-rise building,and the calculation results are in well accordance of those field measured results,thus the validity of time domain analysis method is verified.During typhoon Haikui and Trami,wind-induced acceleration data of the elevator car and layer on Wenzhou building are obtained,and the interaction mechanism of vibration response between elevator car and structure is revealed.Then,the simplified method for calculating the horizontal wind load of elevator is proposed,which is provides a reference for the safety design of elevators.The horizontal vibration model of the elevator car and guide rail system is established under typhoon.Meanwhile,combined with the calculation results of wind-induced response using the finite element method,the influence rules of elevator car operation speed,terrain types,and guide rail bracket stiffness on horizontal vibration acceleration are obtained.All in all,conclusions drawn above can provide theoretical basis for taking measures to control horizontal vibration of elevators in high-rise buildings.