基于环境激励信号的桥梁结构响应在线检测系统,利用高灵敏度三分量宽频带地震计,连续监测北京市四座典型在役桥梁在自然荷载作用下的微弱振动信号,分别利用峰值法和互相关函数法获得了在役桥梁结构不同方向上的频谱特征及其结构响应特征。结果 表明:(1)三分量地震计能够准确可靠地连续记录宽频带范围内的环境激励的微弱振动信号,非常适用于构建新型的桥梁结构响应检测系统;(2)峰值法和互相关函数法都能够可靠地识别多阶桥梁模态频率,互相关函数法的识别结果更为稳定;(3)桥梁的模态频率受桥梁结构、材料、环境温度等多种因素影响,桥梁不同方向的固有振动频率不同,不同类型的桥梁的结构响应也存在显著差异。该桥梁结构响应检测技术为在役桥梁实时健康诊断打下了基础。
We developed a set of bridge structural response online detection system based on ambient vibrating signal, and used high-sensitivity three-component broadband seismometer(CMG-6TD)to continuously monitor the tiny ambient vibrating signal of four typical in-service bridges in Beijing which was under the natural loading. Then we obtained the spectrum characteristic and structural response characteristic of four typical in-service bridges in different direction by the peak amplitude method and cross-correlation function technique respectively. The results show that:(1)The three-component broadband seismometer can continuously record accurate, reliable and tiny ambient vibrating signal in broadband range, and thus, which is extremely suitable for establishing a bridge structural response online detection system.(2)Both peak amplitude method and noise cross-correlation function technique can identify the modal frequencies of multi-step bridges, and the identification result obtained by the noise cross-correlation function technique is more stable.(3)The modal frequency of the bridge are influenced by many factors, such as the bridge structure, materials and ambient temperature etc.. As a consequence, the natural vibration frequencies of bridge are all different in vertical and the horizontal directions. Moreover, the structural responses of different type of bridge also show distinct difference.The develeping bridge structural response detection technology could be the basis of the real-time health of the exciting bridge.
