A STUDY ON DYNAMIC CHARACTERISTICS OF TRADITIONAL WOODEN BUILDING

由于传统的木结构建筑一般都是有价值的文化财产，我们通常要用无损检测的原理来了解它们的动态特性。微振动测量是一种利用高灵敏度传感器测量振幅从1/1000 mm到1/100 mm的建筑物连续微振动的方法。该方法不会对建筑物造成损伤或摇摆，而且在测量过程中传感器容易放置在梁或地板上，具有良好的适用性。为了了解日本传统木结构建筑的动力特性，对9栋建筑进行了微震测量。通过对微震记录的快速傅立叶变换分析，得到了各建筑物的固有频率、阻尼系数和振型。其次，在考虑柱子抗摇摆和粘土墙影响的情况下，估算了其中五栋建筑的侧向荷载-位移关系。利用计算的初始刚度值和质量估计值，得到了平行模振动的固有频率值。最后，将计算得到的固有频率值与微动测量值进行了比较。比较表明，固有频率的计算值与观测值之间有较好的相关性，但计算值的绝对值低于观测值。因此，微震测量作为日本传统木结构建筑抗震性能无损诊断的一种方法似乎是适用的。

As the traditional timber buildinds are generally valuable cultural properties, we usually have to employ the non destructive examination philosophy to understand their dynamic characteristics. Micro tremor measurement is a method of measuring the continuous micro vibration of the buildings whose amplitude is from 1/1000 mm to 1/100 mm with high sensitive sensors. This method is satisfactorily applicable as it is not to damage or swing the buildings and it is easy to place the sensors on the beam or floor during the measurement.To clarify the dynamic characteristics of Japanese traditional timber buildings, micro tremor measurement were performed on nine buildings. By FFT analysis on the record of micro tremor, we obtained natural frequencies , damping factors and vibration modes of each building. Next, the lateral load- displacement relationships of five buildings among them were estimated, considering column rocking resistance and the effect of clay walls. And the values of natural frequency for parallel mode vibration were obtained using calculated values of initial stiffness and the estimated values of mass. Finally , the calculated values of natural frequency were compared with those observed in micro tremor measurements. The comparison showed an adequate correlation between the calculated values and the observed values of natural frequency, though the absolute values by calculation were lower than those observed. Therefore, micro tremor measurement seems to be applicable as one method in non-destructive diagnosis for seismic performance of.Japanese traditional timber buildings.