scholarly journals A System Identification-Based Damage-Detection Method for Gravity Dams

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Masoud Mirtaheri ◽  
Mojtaba Salkhordeh ◽  
Masoud Mohammadgholiha
Keyword(s):  
Wavelet Transform ◽  
Dynamic Properties ◽  
Structural Response ◽  
Cost Effective ◽  
The Body ◽  
Mode Shapes ◽  
Damage Scenarios ◽  
Hilbert Huang Transform ◽  
Random Decrement Technique ◽  
Random Decrement

Dams are essential infrastructures as they provide a range of economic, environmental, and social benefits to the local populations. Damage in the body of these structures may lead to an irreparable disaster. This paper presents a cost-effective vibration-based framework to identify the dynamic properties and damage of the dams. To this end, four commonly occurred damage scenarios, including (1) damage in the neck of the dam, (2) damage in the toe of the structure, (3) simultaneous damage in the neck and the toe of the dam, and (4) damage in the lifting joints of the dam, are considered. The proposed method is based on processing the acceleration response of a gravity dam under ambient excitations. First, the random decrement technique (RDT) is applied to determine the free-vibration of the structure using the structural response. Then, a combined method based on Hilbert–Huang Transform (HHT) and Wavelet Transform (WT) is presented to obtain the dynamic properties of the structure. Next, the cubic-spline technique is used to make the mode shapes differentiable. Finally, Continuous Wavelet Transform (CWT) is applied to the residual values of mode shape curvatures between intact and damaged structures to estimate the damage location. In order to evaluate the efficiency of the proposed method in field condition, 10% noise is added to the structural response. Results show promising accuracy in estimating the location of damage even when the structure is subjected to simultaneous damage in different locations.

scholarly journals Vibration Anatomy and Damage Detection in Power Transmission Towers with Limited Sensors

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1731
Author(s):  
R. Karami-Mohammadi ◽  
M. Mirtaheri ◽  
M. Salkhordeh ◽  
M. A. Hariri-Ardebili
Keyword(s):  
Wavelet Transform ◽  
Power Transmission ◽  
Low Cost ◽  
Structural Response ◽  
Ambient Vibration ◽  
Mode Shapes ◽  
Modal Assurance Criterion ◽  
Realistic Condition ◽  
Damage Scenarios ◽  
Transmission Towers

This study presents a technique to identify the vibration characteristics in power transmission towers and to detect the potential structural damages. This method is based on the curvature of the mode shapes coupled with a continuous wavelet transform. The elaborated numerical method is based on signal processing of the output that resulted from ambient vibration. This technique benefits from a limited number of sensors, which makes it a cost-effective approach compared to others. The optimal spatial location for these sensors is obtained by the minimization of the non-diagonal entries in the modal assurance criterion (MAC) matrix. The Hilbert–Huang transform was also used to identify the dynamic anatomy of the structure. In order to simulate the realistic condition of the measured structural response in the field condition, a 10% noise is added to the response of the numerical model. Four damage scenarios were considered, and the potential damages were identified using wavelet transform on the difference of mode shapes curvature in the intact and damaged towers. Results show a promising accuracy considering the small number of applied sensors. This study proposes a low-cost and feasible technique for structural health monitoring.

scholarly journals Structural Responses of a Supertall Building Subjected to a Severe Typhoon at Landfall

2020 ◽  
Vol 10 (8) ◽  
pp. 2965 ◽  
Author(s):  
Zhi Li ◽  
Jiyang Fu ◽  
Yuncheng He ◽  
Zhen Liu ◽  
Jiurong Wu ◽  
...  
Keyword(s):  
Dynamic Properties ◽  
Damping Ratio ◽  
Field Measurements ◽  
Amplitude Dependence ◽  
Modal Shape ◽  
Stochastic Subspace Identification ◽  
Random Decrement Technique ◽  
Random Decrement ◽  
Combined Use ◽  
Structural Responses

Typhoon Mangkhut (1822) was one of the strongest tropical cyclones that ever impacted the south coast of China in past decades. During the passage of this typhoon, the structural health monitoring (SHM) system installed on a 303 m high building in this region worked effectively, and high-quality field measurements at nine height levels of the building were collected successfully, which provides a valuable opportunity to explore the dynamic properties of the building and the associated wind effects. In this study, the typhoon wind characteristics are presented first based on in-situ measurements at two sites. Acceleration responses of the building is then investigated, and the building’s serviceability is assessed against several comfort criteria. This study further focuses on the identification of modal parameters (i.e., natural frequency, damping ratio, and modal shape) via two methods: stochastic subspace identification (SSI) method and a method based on combined use of spectral analysis and random decrement technique (RDT). The good agreement between the two results demonstrates the effectiveness and the accuracy of the adopted methods. The obtained results are further compared with the stipulations in several technical codes as well as simulation results via finite element method to examine their performances in this real case. The amplitude dependence of natural frequencies and damping ratios of the studied building are also stressed.

Numerical and Empirical Simulation of Linear Elastic Seismic Response of a Building: The Case of Nice Prefecture

2018 ◽  
Vol 34 (1) ◽  
pp. 169-196
Author(s):  
Guillermo Wenceslao Fernández Lorenzo ◽  
Maria Paola Santisi d'Avila ◽  
Anne Deschamps ◽  
Etienne Bertrand ◽  
E. Diego Mercerat ◽  
...  
Keyword(s):  
Seismic Response ◽  
Dynamic Properties ◽  
Alluvial Soil ◽  
Structural Response ◽  
Structural Deformation ◽  
Mode Shapes ◽  
Deformation Analysis ◽  
Fe Model ◽  
Linear Elastic ◽  
Rc Building

The structural motion of a tall reinforced concrete (RC) building on alluvial soil in Nice (France) is continuously recorded using accelerometers. The structural behavior of the building is studied using operational modal analysis (OMA) to identify its dynamic properties, a finite element (FE) model to reproduce the building response, and empirical Green's functions (EGFs) to generate the structural response to ground motions stronger than those registered in the analyzed seismic area. These different approaches are applied for the analysis of seismic response of the instrumented building and results are consistent. The FE model is calibrated by comparing natural frequencies and mode shapes with those obtained using OMA. Numerically-simulated time histories are qualitatively and quantitatively compared with recordings showing good agreement. Based on regional earthquakes, linear seismic response of the building is simulated for a stronger scenario earthquake using EGF. This approach allows for structural deformation analysis of existing buildings without the need of structural plans and mechanical parameter calibration in the case where the seismic response is within linear elastic regime.

scholarly journals Beam Damage Detection Under a Moving Load Using Random Decrement Technique and Savitzky–Golay Filter

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 243 ◽  
Author(s):  
Hadi Kordestani ◽  
Chunwei Zhang ◽  
Mahdi Shadabfar
Keyword(s):  
Damage Detection ◽  
Moving Load ◽  
Damage Index ◽  
Velocity Variation ◽  
Simply Supported Beam ◽  
Damage Scenarios ◽  
Simply Supported ◽  
Random Decrement Technique ◽  
Random Decrement ◽  
Output Only

In this paper, a two-stage time-domain output-only damage detection method is proposed with a new energy-based damage index. In the first stage, the random decrement technique (RDT) is employed to calculate the random decrement signatures (RDSs) from the acceleration responses of a simply supported beam subjected to a moving load. The RDSs are then filtered using the Savitzky–Golay filter (SGF) in the second stage. Next, the filtered RDSs are processed by the proposed energy-based damage index to locate and quantify the intensity of the possible damage. Finally, by fitting a Gaussian curve to the damage index resulted from the non-damage conditions, the whole process is systematically implemented as a baseline-free method. The proposed method is numerically verified using a simply supported beam under moving sprung mass with different velocities and damage scenarios. The results show that the proposed method can accurately estimate the damage location/quantification from the acceleration data without any prior knowledge of either input load or damage characteristics. Additionally, the proposed method is neither sensitive to noise nor velocity variation, which makes it ideal when obtaining a constant velocity is difficult.

scholarly journals The use of random decrement technique for long term health monitoring of concrete structures

2021 ◽  
Author(s):  
Rana Morsy
Keyword(s):  
Damage Detection ◽  
Health Monitoring ◽  
Nuclear Power ◽  
Concrete Beams ◽  
Dynamic Properties ◽  
Offshore Platforms ◽  
Random Decrement Technique ◽  
Power Stations ◽  
Random Decrement ◽  
Detection Approach

This investigation deals with the development of an advanced strategy for Structural Health Monitoring (SHM) of concrete beams and girders for important structures such as bridges, offshore platforms and nuclear power stations using smart monitoring systems, including an effective diagnostic approach for damage detection with a reliability-based performance ranking. The proposed strategy can be classified into four main sections: identification of the existence of damage, determination the localization of the damage, estimation the level of damage, and assessing the seriousness of the damage regarding the structure’s service life. Random Decrement (RD) is an accurate dynamic analysis diagnostic tool that has been used effectively for SHM; the technique has been used within various fields in mechanical, aerospace, and, recently, civil engineering. The damage detection approach is based on the RD technique. A theoretical, numerical, and experimental investigation has been conducted on concrete beams using the RD technique for damage detection in terms of changes in the dynamic properties and used at successive multiple points under certain leading point conditions to determine the location of damage through the development of the Multi-Channel Random Decrement (MCRD).

scholarly journals The use of random decrement technique for long term health monitoring of concrete structures

2021 ◽  
Author(s):  
Rana Morsy
Keyword(s):  
Damage Detection ◽  
Health Monitoring ◽  
Nuclear Power ◽  
Concrete Beams ◽  
Dynamic Properties ◽  
Offshore Platforms ◽  
Random Decrement Technique ◽  
Power Stations ◽  
Random Decrement ◽  
Detection Approach

This investigation deals with the development of an advanced strategy for Structural Health Monitoring (SHM) of concrete beams and girders for important structures such as bridges, offshore platforms and nuclear power stations using smart monitoring systems, including an effective diagnostic approach for damage detection with a reliability-based performance ranking. The proposed strategy can be classified into four main sections: identification of the existence of damage, determination the localization of the damage, estimation the level of damage, and assessing the seriousness of the damage regarding the structure’s service life. Random Decrement (RD) is an accurate dynamic analysis diagnostic tool that has been used effectively for SHM; the technique has been used within various fields in mechanical, aerospace, and, recently, civil engineering. The damage detection approach is based on the RD technique. A theoretical, numerical, and experimental investigation has been conducted on concrete beams using the RD technique for damage detection in terms of changes in the dynamic properties and used at successive multiple points under certain leading point conditions to determine the location of damage through the development of the Multi-Channel Random Decrement (MCRD).

Random Decrement Technique Based on the Sampling Methods

2011 ◽  
Vol 243-249 ◽  
pp. 5413-5419
Author(s):  
Chuan Xiong Zhang ◽  
Wen Hai Shi ◽  
Zheng Nong Li
Keyword(s):  
Sampling Method ◽  
Sampling Methods ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Structural System ◽  
Random Decrement Technique ◽  
Linear Dynamic ◽  
Random Decrement ◽  
Effective Use

This paper presents the random decrement (RD) technique based on the sampling method for parameter identification of linear dynamic system. The development of RD technique was elaborated briefly in the aspects of identifying the dynamic properties, and then this paper summarized the corresponding parameters recognition problems due to the quantity and quality of measured sampling segments. Detailed analysis of two kinds of sampling method (the probability-proportional-to-size and two-stage sampling) is conducted to investigate its adaptation range in extracting RD signatures. The results of two simulated examples indicates that in view of the different vibration parameter recognition situation, the above provided RD technique based on different sampling methods could improve the quality of RD signature obviously, and lead to a quite accurate frequency and the damping ratio of structural system under the effective use of all measured sampling segments.

scholarly journals Experimental modal identification and fem updating of a seven story isolated educational building

2019 ◽  
Vol 29 (2) ◽  
Author(s):  
Rony Reategui ◽  
Estefanía Bossus ◽  
Mauricio Gonzales ◽  
Diego Villagomez ◽  
Rafael Aguilar
Keyword(s):  
Degrees Of Freedom ◽  
Numerical Models ◽  
Dynamic Properties ◽  
Structural Response ◽  
Experimental Tests ◽  
Cost Effective ◽  
Element Model ◽  
Modal Identification ◽  
Ambient Vibration ◽  
National Regulation

The construction of isolated structures is increasing in recent decades in seismic countries. In Peru, the national regulation indicates that important buildings such as hospitals located in areas of high seismic risk must incorporate isolation systems to reduce structural and nonstructural loss. These systems protect the main structure from the effects of a seismic event by separating its base from the earth movement and by reducing the relative displacements and accelerations between adjacent stories. In the structural design process of buildings and seismic protection systems, having numerical models that properly represent the real behavior of the buildings is of high importance. In this context, experimental modal tests represents an attractive cost-effective non-destructive tool to obtain an accurate characterization of the experimental structural response. This paper presents the experimental tests carried out in a base-isolated educational building built in 2014 that has seven stories and three basements with a total built area of around 7500 m2. Data acquisition was accomplished with autonomous units (acquisition system and transducers incorporated in a single unit) whose versatility allowed measuring a significant number of degrees of freedom in a limited amount of time. The dynamic properties experimentally identified were used to calibrate the finite element model of the building. The results showed that the design model approximates correctly to the experimentally identified ambient vibration response when considering rigid supporting conditions as well as the interaction of partitioning elements such as walls and parapets.

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