Study On The Influence Of Side Ratio On Wind Load Of Super High-rise Buildings

With the rapid development of super high-rise buildings,there is already a basis for the transition of building sections from square sections to rectangular sections with large side ratio.Super high-rise buildings usually have the characteristics of large flexibility,low natural frequency,and are very sensitive to wind loads.Therefore,wind loads have become one of the main control loads for the design of super high-rise buildings.Under the above background,this paper selects multiple super high-rise building models with rectangular sections of different side ratios as the research objects,and studies its wind load characteristics and wind-induced response by means of synchronous pressure measurement wind tunnel tests.The specific research contents are as follows:A series of wind tunnel tests were carried out in terrain category B.Based on the results of wind tunnel tests,the variation of wind pressure on the surface of each model with the wind azimuth was studied.According to the wind pressure coefficient of the lateral surface of some large side ratio building models,the problem of bluff body flow is studied,which reflects the specific law of large side ratio building models under wind loads.Afterwards,the correlation coefficients and coherence functions of the fluctuating wind pressure on the facades of each model were analyzed from the horizontal and vertical directions.Its frequency domain characteristics are revealed,and conditions are created for solving random wind-induced responses.The variation of the three-component force coefficient with height was studied,and it was found that when the side ratio was a critical value of 0.5,the mean resistance coefficient and the fluctuating resistance coefficient reached the maximum at the same time.When the aspect ratio of super high-rise buildings is the same,compared to a rectangular section with a side ratio other than 1,super high-rise building with a square section bears less torque.The acrosswind force power spectrum of each model at typical measurement point layers was studied,and it was found that when the side ratio was not greater than 1,the Strouhal numbers corresponding to the models were around 0.1.When the side ratio is 0.5,the ordinate of the acrosswind force power spectrum curve takes the maximum value,which means that the energy generated by the vortex shedding on the lateral surface is the largest at this time.When the side ratio is greater than 2,two peaks appear in the power spectrum curve.Among them,the spectral peak in the high frequency range is due to the reattachment of the separated flow,which results in the generation of secondary vortices.The reduced frequency corresponding to the spectral peak of the high frequency band is the superior frequency of secondary vortex shedding.Based on the random vibration theory,the equivalent static wind load and peak acceleration at the top of each model were studied.The effects of damping ratio,basic wind pressure,height and wind azimuth on the equivalent static wind load and wind-induced response of super tall buildings with different side ratios were discussed for the reference of related engineering designers.