环境振动下传统木结构的动力响应现场实测

In-situ measurements of dynamic responses of traditional timber buildings under ambient vibration

地铁线和交通干线附近的传统木结构常处于微幅振动状态,为研究环境振动下传统木结构的动力响应特点,对北京 4 号线菜市口至陶然亭区段附近的六檩抬梁式木结构进行现场测试。首先以柱顶水平速度峰值为指标得到传统木构整体的环境振动响应特点,然后对一榀木构架的柱脚输入进行时域和功率谱密度分析得到环境振源特征,最后对柱脚输入和柱顶输出进行 1/3 倍频程下的振动传递比分析,得到实测木构的动力响应特点。测试结果表明:地铁交通是该传统木构环境振动的主要振源,对南北向高频段(50~90Hz)进行减隔振处理,理论上能有效降低该传统木构的地铁致环境振动响应。

As located either near subway or road traffic lines, traditional timber buildings are subjected to micro vibrations. In order to study the characteristic of dynamic response under ambient vibration, in-situ measurements were performed on a Tailiang-style timber building with six purlins in proximity to tracks between Caishikou Station and Taoranting Station on Line 4 of Beijing Metro. Firstly, the environmental vibration response characteristics of the traditional wood structure are obtained by using the horizontal peak velocity of the measuring point at the top of the column. Next, the characteristics of the environmental vibration source are obtained by analyzing the time-domain indexes and power spectral density of the vibrations at the base of the column. Finally the transfer ratio of the vibration at the base and top of the eave column in one-third octave band domain is analyzed. The analysis results indicate that the subway traffic behaves as the main vibration source for the ambient vibrations of traditional wood. The ambient vibration responses can be effectively reduced through mitigating the bands between 50 and 90Hz.