台风激励下海口市某高层建筑模态参数识别

Modal parameter identification of a high-rise building in Haikou city during typhoons

对2014-2017年期间一栋由4根巨柱支撑、高108 m的32层塔楼在台风影响下的楼顶风场和动力响应进行同步监测,获得台风"威马逊"、"海鸥"、"彩虹"、"莎莉嘉"和"卡努"影响下该楼顶部的风速、风向和不同楼层沿长、短轴向的加速度响应时程,分析了加速度响应的时域和频域特性,采用ERA-NExT、RDT、有限元法识别了实测高层建筑的模态参数,研究了与加速度幅值相关的模态频率和阻尼比。统计结果表明:强风作用下高层建筑模态频率低于静风状态下的模态频率,当加速度均方根小于10 mm/s^2时,顺、横风向前三阶模态频率随加速度幅值增大而减小,顺风向前三阶模态阻尼比随加速度幅值增大而增大;当加速度均方根大于10 mm/s^2时,顺、横风向前三阶模态频率减小速率逐步减小,顺风向前三阶模态阻尼比未出现明显增大。当峰值加速度达到最大时,沿长、短轴向一阶模态阻尼比约为2. 0%、1. 9%,相比静风状态下前三阶模态频率下降了约11%、12%、10%,并提出了考虑相对加速度幅值(加速度均方根与测点离地高度比值)参数影响的高层建筑基频预测公式,为台风多发区域高层建筑基频的估算提供参考。

The measured high-rise building,with a height of 108 m,has 32 stories and is supported by 4 huge columns. Wind-field characteristics atop the building,acceleration responses along the longitudinal and lateral axes were monitored synchronously during the passage of Typhoon Rammasun,Kalmaegi,Mujigae,Sarika and Khanun from 2014 to 2017. The time-domain and frequency-domain characteristics of acceleration responses were analyzed. The modal parameters of the measured building were identified by ERA-NExT,RDT and the finite element method,and the amplitude-dependent modal damping ratios and frequencies were investigated. The statistical results show that the modal frequencies of high-rise buildings under strong wind are lower than those under static wind condition. When root mean square (RMS) of acceleration is less than 10 mm/s^2,the along-wind and across-wind modal frequencies at the first three orders decrease with the increasing acceleration,while the along-wind damping ratios at the first three orders increase with the increasing acceleration. When RMS of acceleration is greater than 10 mm/s^2,the reduction rate of the along-wind and across-wind modal frequency at the first three orders reduces,and the along-wind modal damping ratios at the first three orders don’t increase significantly. The reduction ratio in the modal frequencies at the first three orders are 11%,12%,10% compared with that of the static wind condition,in sequence,and the first modal damping ratios along the longitudinal and lateral axes are about 2. 0% and 1. 9% respectively,when the peak acceleration reaches a maximum value. The prediction formula of high-rise buildings considering the factor of relative acceleration amplitude (the ratio of RMS of accelerations at ith floor to its height) is proposed to provide references for the estimation of fundamental frequency in typhoon-prone regions.