上海中心大厦悬挂式幕墙支撑结构竖向地震作用反应分析

Analysis on vertical seismic response of curtain wall support structure of the Shanghai Tower

当悬挂结构自身的竖向振动周期与其支承结构的竖向振动周期接近,将出现二次共振现象,即产生竖向振动的"鞭梢效应",从而导致悬挂结构自身及其支承结构的竖向地震作用反应都显著增大。上海中心大厦采用分区悬挂的柔性幕墙支撑结构,每个分区悬挂的幕墙质量大、支承结构刚度弱、悬挂高度高、自振周期与主楼接近,其竖向地震作用反应不容忽视。采用反应谱和弹性时程分析方法,对上海中心悬挂式幕墙支撑结构在竖向地震作用下的结构自振特性、竖向加速度、竖向位移等反应进行了分析。结果表明:悬挂式的幕墙支撑结构竖向地震作用反应显著,幕墙支撑结构的竖向地震作用反应随结构高度增加而增大;高区吊杆轴重比较低区增大约1.2倍,高区吊点加速度反应较低区增加约1.5倍;在相同分区,由于吊杆弹性放大作用,幕墙支撑结构底部的轴重比、加速度、位移反应分别较顶部增大20%、50%、100%。

When vertical natural period of suspension structure approaches the natural period of support structure, secondary resonance may be excited, which means ＇ whipping effect of vertical vibration＇ , happens, resulting in the increased vertical seismic response of suspension structure and its support structure significantly. A unique flexible suspension curtain wall support structure （CWSS） was developed for the Shanghai Tower. Due to its characteristics of heavy weight, flexibility of support stiffness, high altitudes suspension and natural period approaching main structure, the vertical seismic response cannot be ignored. Research on vertical seismic force, vertical acceleration and vertical displacement response of the CWSS was carried out by using the response spectra and elastic time history analysis method. Study results show that vertical seismic response of CWSS is significant. Seismic response of CWSS increases with increasing height of main structure. Compared with lower zone, the axial force-weight ratios and acceleration of suspension point in higher zone increase by about 120% and 150%, And in the same zone, because of amplification effect of rods, Compared with the top, axial force-welght ratios, acceleration and displacement at the bottom increase by about 20%, 50% and 100% respectively.