大跨屋盖结构风效应的风洞试验与原型实测研究

Wind Tunnel and Full-scale Study of Wind Effects on a Large Roof Structure

以广州国际会展中心为工程案例,进行了刚性模型风洞试验和有限元模态分析,在此基础上计算了屋盖的风致位移响应,结果表明,对于屋盖风振响应影响最大的因素是结构的基阶振型,其次才是风荷载;随着阻尼比的增加,位移响应谱的共振峰得到了有效平抑,峰值位移响应也随之减小.基于现场实测,提出功率谱点积识别大跨屋盖结构竖向整体振动固有频率的方法,并与有限元计算结果进行了对比分析,实测得到的前4阶固有频率与振型均能与有限元模型较好吻合,其中基阶固有频率的相对误差仅为0.3%,证明了该方法的有效性.

In this study, a wind tunnel test was conducted for Guangzhou International Exhibition Cen- tre. Simultaneous pressure measurements were made on its rigid roof model in a boundary layer wind tun- nel. Meanwhile, a three-dimensional finite element model of the roof structure of Guangzhou International Exhibition Centre was established on the basis of the structural design drawings, and the dynamic charac- teristics were analyzed on the basis of the established finite element model. Furthermore, wind-induced re- sponses of the large roof were computed and the wind loading inputs were derived from the simultaneous pressure measurements on the rigid roof model. The results showed that the influences of the structural fundamental modes on the wind-induced vibration of the roof were generally more significant than wind loads. It was also observed from the wind tunnel measurements that there was a tendency for the peak dis- placement response to decrease with the increase of the damping ratio. On the other hand, full-scale meas- urements of the wind effects on the large roof were conducted under strong wind action. Based on field measurement results, a new method to identify the first several natural frequencies of the roof in vertical direction, using the dot matrix of power spectrum density approach, was presented. Comparison of the frequency results determined by the proposed method and those obtained from the finite element model analysis was done to examine the applicability and accuracy of the proposed method.