基于ITD法的结构模态参数识别

Modal Parameter Identification of Structure Based on ITD Method

本文运用ITD(Ibrahim Time Domain)法来识别振动台模型试验的模态参数。在基于结构动力响应的分析中识别结构的模态参数是结构健康监测和损伤识别等研究及工程实践的重要内容,也是前提和难点。本文首先运用随机减量法对振动台激励下的结构振动响应数据进行预处理,然后用ITD法识别出结构的频率、阻尼比和振型系数。利用本方法对同济大学土木工程防灾国家重点实验室12层钢筋混凝土框架模型振动台试验数据进行了分析,并将识别结果与有限元分析软件的数值模拟进行了对比。结果发现:模型试验结构的3～6层为结构的薄弱位置,且自振频率在随着加速度不断增加的地震波输入下呈阶梯形下降了两阶,之后呈现波动状态,结构振型在第27工况之后也和前面有明显的改变。

Ibrahim Time Domain （ITD） method was used to identify the modal parameters of shaking table model experiment in this paper. Modal parameter identification based on dynamic response signal of the structure is the critical component for structural health monitoring and damage detection. Firstly, the response data from structure shaking table of incentive and vibration will be preprocessed by using of Random Decrement Method. Then, the frequency, damping ratio and the coefficient of vibration mode of structure are identified with ITD method, the data taken from a shaking table test on a 12-storey reinforced concrete frame model were analyzed in Tongji University by using the method, and the results and finite element analysis software numerical simulation were compared. Furthermore, the analysis results show that the natural frequency decreases with fluctuant condition after stepladder shape with the increasing acceleration data of seismic wave input as the weak position at 3 to 6 layers of structure model, Structural vibration mode showed obvious change after 27th conditions.