Evaluation Of Wind-Induced Effect On Seismically Isolated High-Rise Building

The implementation of the Standard for Seismic Isolation Design of Building(GB/T51408-2021)symbolized the milestone progress of the seismic isolation technology in our country.According to incomplete statistics,the number of seismically isolated buildings built in China has exceeded 15,000,distributed in 19 provinces and cities,and is still growing rapidly.At the same time,with the continuous development of urbanization,seismic isolation technology has been promoted and quoted in high-rise structures accordingly,and the seismically isolated buildings are built higher and higher.Compared with seismic action,seismically isolated high-rise structures are often more susceptible to strong wind loads,and the wind vibration problem of seismically isolated high-rise structures cannot be ignored.The current research on the seismic performance of seismically isolated structure has already achieved certain results,and the corresponding standard has also raised the seismic protection target of seismically isolated structure from frequent earthquake to moderate earthquake,which means that the seismically isolated structure will have better seismic performance and sufficient safety reserve.However,there are still relatively few studies on wind-induced effects of seismically isolated high-rise structures,and the new and old seismic isolation design standards have not been changed in the wind-resistance design of seismically isolated structure.Both of them stipulate the wind-resistance stability of seismic isolation interface through static design.The wind-induced response of the superstructure and wind-resistance stability of the seismic isolation interface need to be further analyzed and evaluated.Therefore,in order to improve the wind-resistance design method of the seismically isolated structure,this paper investigate the wind effect of the seismically isolated high-rise structure.The main research contents are as follows:(1)Firstly,a hundred-meter seismically isolated high-rise structure in China is selected to carry out the comparative research on the seismic isolation design method.The new and old seismic isolation design methods are compared in four aspects: seismic fortification target,design process,design response spectrum and theoretical basis.The theoretical core of the integrated seismic isolation design method,complex mode decomposition response spectrum and CCQC method,equivalent linearization iterative method and performance-based design method,are introduced emphatically.Then,the integrated seismic isolation design method,traditional divisional seismic isolation design method and traditional seismic design method are used to design the high-rise seismically isolated structure,and the reinforcement results under different design methods are compared from the perspective of economy.(2)The basic characteristics of mean and pulsating winds are first introduced;the current wind-resistance design methods for seismic isolation structures are reviewed;Based on current national codes,an analysis approach for evaluating the wind-induced effect on seismically isolated high-rise structures is proposed.This analysis approach is used to analyze the windinduced effects of the 100-meter-level seismically isolated high-rise structure in Chapter 2,and to evaluate the wind-induced response of the superstructure and wind-resistance stability of the seismic isolation interface under the current wind-resistant design requirements.In addition,the wind-resistance stability of the seismic isolation interface of the seismically isolated highrise structure under the wind loads with 100-year,200-year,300 year,and 475 year beyond the fortification return period is discussed.(3)The mechanism of cross-wind vortex vibration is introduced,including Reynolds number effect and cylindrical winding phenomenon;The necessary conditions for the occurrence of vortex resonance in a seismically isolated high-rise structure are explained;The analysis approach of crosswind-induced effect of seismically isolated high-rise structure with circular cross section is proposed based on Luman’s mechanical model,and combined with the wind-induced effect analysis approach of seismically isolated high-rise structure under along wind load proposed in Chapter 3.The wind vibration comfort and the wind stability of the seismic isolation interface under alongwind load and crosswind load are compared and investigated;Based on the equivalent linearized iterative principle,an iterative calculation method for the crosswind-induced effect of seismically isolated high-rise structure considering the nonlinear characteristics of the seismic isolation interface is proposed;The wind stability of seismically isolated high-rise structures under crosswind load with longer return periods is also explored with reference to the fortification return period of moderate earthquake.