【摘要】 以抗震设防水平不高、抗震构造措施不足且已经服役多年的低延性钢筋混凝土框架结构1/5缩尺振动台试验模型为研究对象,为捕捉在低强度振动中砌体填充墙与主体框架开裂行为以及框架自身发生开裂导致动力特性变化趋势,采用强度小、持时短的白噪声进行扫频。采用自然激励技术和特征系统实现算法对试验加速度信号分析,识别出试验模型完备模态;采用小波变换提取各阶模态的楼层加速响应并进行分析。研究结果显示:特征系统实现算法适用于低强度振动中的动力特性识别;高阶模态对既有框架结构加速度响应贡献显著。更多还原

【Abstract】 This paper presents the dynamic properties of a model for a five-story, 1/5-scaled low-ductile infilled reinforced concrete frame by applying a dynamic test. The low-ductile structure was designed in terms of poor seismic fortification level, insufficient seismic fortification measures, and long service ages. The masonry infilled walls would separate from major structure members or cracked under a low intensity excitation, so that the white noise used for the specimen had a low amplitude and short duration. The system identification of the specimen was extracted from floor accelerations under white noise excitations by the eigensystem realization algorithm method and nature excitation technique. The acceleration response of each mode was analyzed, which extracted by a wavelet transform. It is shown that the eigensystem realization algorithm method is effective for a lower strength vibration. A high modal vibration is easy to occur for existing RC frame.更多还原