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modal parameter identification and damping ratio estimation from the full-scale measurements of a typical Tibetan wooden structure

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Earthquake Engineering and Engineering Vibration 2016年第4期15卷 681-695页

作者： Dai Lu Yang Na S.S.Law Yang Qingshan School of Civil Engineering Beijing Jiaotong University

Tibetan heritage buildings have a high historical and cultural value. They have endured adverse environmental loadings over hundreds of years without significant damage. However, there are few reports on their structural characteristics under normal environmental loadings and their behavior under dynamic loadings. In this research, a typical Tibetan wooden wall-frame building is selected to study its dynamic characteristics. Field measurements of the structure were conducted under environmental excitation to collect acceleration responses. The stochastic subspace identification （SSI） method was adopted to calculate the structural modal parameters and obtain the out-of-plane vibration characteristics of the slab and frames. The results indicated that the wall-frame structure had a lower out-of-plane stiffness and greater in-plane stiffness due to the presence of stone walls. Due to poor identified damping ratio estimates from the SSI method, a method based on the variance upper bound was proposed to complement the existing variance lower bound method for estimating the modal damping ratio to address the significant damping variability obtained from different points and measurements. The feasibility of the proposed method was illustrated with the measured data from the floor slab of the structure. The variance lower and upper bound methods both provided consistent results compared to those from the traditional SSI method.

关键词： Tibetan wooden structure field test modal parameters damping ratio variance upper/lower bound

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维普期刊数据库

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DPCM-based vibration sensor data compression and its effect on structural system identification

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Earthquake Engineering and Engineering Vibration 2005年第1期4卷 153-163页

作者：张云峰李健 Department of Civil & Environmental Engineering Lehigh University Bethlehem PA 18015 USAAssistantProfessor Department of Civil & Environmental Engineering Lehigh University Bethlehem PA 18015 USA Graduate Researcher

Due to the large scale and complexity of civil infrastructures, structural health monitoring typically requires a substantial number of sensors, which consequently generate huge volumes of sensor data. Innovative sensor data compression techniques are highly desired to facilitate efficient data storage and remote retrieval of sensor data. This paper presents a vibration sensor data compression algorithm based on the Differential Pulse Code Modulation (DPCM) method and the consideration of effects of signal distortion due to lossy data compression on structural system identification. The DPCM system concerned consists of two primary components: linear predictor and quantizer. For the DPCM system considered in this study, the Least Square method is used to derive the linear predictor coefficients and Jayant quantizer is used for scalar quantization. A 5-DOF model structure is used as the prototype structure in numerical study. Numerical simulation was carried out to study the performance of the proposed DPCM-based data compression algorithm as well as its effect on the accuracy of structural identification including modal parameters and second order structural parameters such as stiffness and damping coefficients. It is found that the DPCM-based sensor data compression method is capable of reducing the raw sensor data size to a significant extent while having a minor effect on the modal parameters as well as second order structural parameters identified from reconstructed sensor data.

关键词： data compression instrumentation linear predictor modal parameters sensor system identification vibration

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维普期刊数据库

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Study of Structural Damage Recognition Based on the Perturbations of Curvature Mode and Frequency

Study of Structural Damage Recognition Based on the Perturba...

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第十一届南方计算力学学术会议（SCCM-11）

作者： Wei He Huai Chen Rong He School of Civil Engineering Zhengzhou University School of Civil Engineering and Communication North China University of Water Resource and Electric Power

A new method for structural damage identification is presented based on the perturbations of curvature mode and frequency. Firstly, the structure mass and stiffness matrixes are expressed as functions of the element physical parameters which reflect the damaged state of the element. According to the change of the curvature mode between the structure in its undamaged and damaged state the possible damage equations(PDE) and the determined damage equations(DDE) are established. The element damage parameters are solved from PDE and DDE. Then the reasonable solution is substituted into the checking damage equation(CDE) based on the change of frequency of the damaged structure to ensure the accuracy of recognition result. Numerical examples show that to identify damage only one order mode needs to be tested. When the degree of damage is low, the first order perturbation equations could be used to recognize the damage with enough accuracy. And if the damage extent were great, the second order perturbation equations could be used to improve the accuracy of identification results.

关键词： modal parameters damage identification curvature mode frequency perturbation

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