Measurements Selection for Bias Reduction in Structural Damage Identification

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Yuhang Liu ◽  
Shiyu Zhou ◽  
Yong Chen ◽  
Jiong Tang
Keyword(s):  
Structural Damage ◽  
Natural Frequencies ◽  
Damage Identification ◽  
Least Square Method ◽  
Linearization Method ◽  
Bias Reduction ◽  
Least Square ◽  
L1 Norm ◽  
Measurement Selection ◽  
Optimal Set

Linearization of the eigenvalue problem has been widely used in vibration-based damage detection utilizing the change of natural frequencies. However, the linearization method introduces bias in the estimation of damage parameters. Moreover, the commonly employed regularization method may render the estimation different from the true underlying solution. These issues may cause wrong estimation in the damage severities and even wrong damage locations. Limited work has been done to address these issues. It is found that particular combinations of natural frequencies will result in less biased estimation using linearization approach. In this paper, we propose a measurement selection algorithm to select an optimal set of natural frequencies for vibration-based damage identification. The proposed algorithm adopts L1-norm regularization with iterative matrix randomization for estimation of damage parameters. The selection is based on the estimated bias using the least square method. Comprehensive case analyses are conducted to validate the effectiveness of the method.

Application of Bayesian statistical method in sensitivity-based seismic damage identification of structures: Numerical and experimental validation

2018 ◽  
Vol 17 (5) ◽  
pp. 1255-1276 ◽  
Author(s):  
Maryam Vahedi ◽  
Faramarz Khoshnoudian ◽  
Ting Yu Hsu
Keyword(s):  
Statistical Method ◽  
Structural Damage ◽  
Damage Identification ◽  
Model Updating ◽  
Least Square Method ◽  
Element Model ◽  
Least Square ◽  
Detection Methods ◽  
Sensitivity Equation ◽  
Stiffness Reduction

Most of the developed sensitivity-based damage detection methods are based on the application of external excitations which could be prohibitive due to infeasible excitation of all structural degrees of freedom. In this regard, identification of damage properties using seismic structural response would be advantageous. In this research, sensitivity-based finite element model updating method is proposed to identify structural damage by earthquake response in the frequency domain and the transfer function of the structure due to ground excitation. The obtained sensitivity equation is solved by linear least square method through defining constraints on the design variables. Since the attainable measured data are restricted by limits on the instrumentations and preciseness of the measurements and due to the fact that only a few of the lower modes of a structure can generally be determined with confidence, a Bayesian statistical method is utilized to enhance the reliability of the predicted damage properties. The proposed technique is applied to a numerical frame model and an experimental six-story steel structure with various scenarios of story stiffness reduction. The results are indicative of the capability of the proposed method for identification of damage location and severity.

scholarly journals Identification of Structural Damage in Bridges Using High-Frequency Vibrational Responses

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Ivana Mekjavić
Keyword(s):  
High Frequency ◽  
Structural Damage ◽  
Natural Frequencies ◽  
Damage Identification ◽  
Damage Model ◽  
Reinforced Concrete Beam ◽  
Computational Technique ◽  
Damage Scenarios ◽  
Identification Approach ◽  
Girder Bridge

The present research aims to develop an effective and applicable structural damage detection method. A damage identification approach using only the changes of measured natural frequencies is presented. The structural damage model is assumed to be associated with a reduction of a contribution to the element stiffness matrix equivalent to a scalar reduction of the material modulus. The computational technique used to identify the damage from the measured data is described. The performance of the proposed technique on numerically simulated real concrete girder bridge is evaluated using imposed damage scenarios. To demonstrate the applicability of the proposed method by employing experimental measured natural frequencies this technique is applied for the first time to a simply supported reinforced concrete beam statically loaded incrementally to failure. The results of the damage identification procedure show that the proposed method can accurately locate the damage and predict the extent of the damage using high-frequency (here beyond the 4th order) vibrational responses.

A Flexibility-Based Method for Structural Damage Identification Using Ambient Modal Data

2009 ◽  
Vol 24 (3) ◽  
pp. 153-159 ◽  
Author(s):  
Q. W. Yang
Keyword(s):  
Structural Damage ◽  
Damage Identification ◽  
Simulated Data ◽  
Least Square ◽  
Ambient Vibration ◽  
Mode Shapes ◽  
Vibration Modes ◽  
Sensitivity Equation ◽  
Structural Damage Identification ◽  
Normalization Factors

Structural damage identification using ambient vibration modes has become a very important research area in recent years. The main issue surrounding the use of ambient vibration modes is the mass normalization of the measured mode shapes. This paper presents a promising approach that extends the flexibility sensitivity technique to tackle the ambient vibration case. By introducing the mass normalization factors, manipulating the flexibility sensitivity equation, the unknown damage parameters and mass normalization factors can be computed simultaneously by the least-square technique. The effectiveness of the proposed method is illustrated using simulated data with measurement noise on three examples. It has been shown that the proposed procedure is simple to implement and may be useful for structural damage identification under ambient vibration case.

scholarly journals Temperature Effects on Vibration-Based Damage Detection of a Reinforced Concrete Slab

2020 ◽  
Vol 10 (8) ◽  
pp. 2869 ◽  
Author(s):  
Zhenpeng Wang ◽  
Minshui Huang ◽  
Jianfeng Gu
Keyword(s):  
Elastic Modulus ◽  
Reinforced Concrete ◽  
Ambient Temperature ◽  
Temperature Effects ◽  
Structural Damage ◽  
Natural Frequencies ◽  
Damage Identification ◽  
Mode Shapes ◽  
Arx Model ◽  
Rc Slab

To study the variations in modal properties of a reinforced concrete (RC) slab (such as natural frequencies, mode shapes and damping ratios) under the influence of ambient temperature, a laboratory RC slab is monitored for over a year, the simple linear regression (LR) and autoregressive with exogenous input (ARX) models between temperature and frequencies are established and validated, and a damage identification based on particle swarm optimization (PSO) is utilized to detect the assumed damage considering temperature effects. Firstly, the vibration testing is performed for one year and the variations of natural frequencies, mode shapes and damping ratios under different ambient temperatures are analyzed. The obtained results show that the change of ambient temperature causes a major change of natural frequencies, which, on the contrary, has little effect on damping ratios and modal shapes. Secondly, based on a theoretical derivation analysis of natural frequency, the models are determined from experimental data on the healthy structure, and the functional relationship between temperature and elastic modulus is obtained. Based on the monitoring data, the LR model and ARX model between structural elastic modulus and ambient temperature are acquired, which can be used as the baseline of future damage identification. Finally, the established ARX model is validated based on a PSO algorithm and new data from the assumed 5% uniform damage and 10% uniform damage are compared with the models. If the eigenfrequency exceeds the certain confidence interval of the ARX model, there is probably another cause that drives the eigenfrequency variations, such as structural damage. Based on the constructed ARX model, the assumed damage is identified accurately.

scholarly journals Optimal Placement of Virtual Masses for Structural Damage Identification

Sensors ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 340
Author(s):  
Jilin Hou ◽  
Zhenkun Li ◽  
Qingxia Zhang ◽  
Runfang Zhou ◽  
Łukasz Jankowski
Keyword(s):  
Structural Damage ◽  
Natural Frequencies ◽  
Damage Identification ◽  
Pso Algorithm ◽  
Optimal Placement ◽  
Beam Structure ◽  
Sensitivity Matrix ◽  
Swarm Optimization ◽  
Placement Optimization ◽  
Mutual Independence

Adding virtual masses to a structure is an efficient way to generate a large number of natural frequencies for damage identification. The influence of a virtual mass can be expressed by Virtual Distortion Method (VDM) using the response measured by a sensor at the involved point. The proper placement of the virtual masses can improve the accuracy of damage identification, therefore the problem of their optimal placement is studied in this paper. Firstly, the damage sensitivity matrix of the structure with added virtual masses is built. The Volumetric Maximum Criterion of the sensitivity matrix is established to ensure the mutual independence of measurement points for the optimization of mass placement. Secondly, a method of sensitivity analysis and error analysis is proposed to determine the values of the virtual masses, and then an improved version of the Particle Swarm Optimization (PSO) algorithm is proposed for placement optimization of the virtual masses. Finally, the optimized placement is used to identify the damage of structures. The effectiveness of the proposed method is verified by a numerical simulation of a simply supported beam structure and a truss structure.

scholarly journals Damage Identification in Structures Based on Energy Curvature Difference of Wavelet Packet Transform

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Pengbo Wang ◽  
Qinghe Shi
Keyword(s):  
Structural Damage ◽  
Natural Frequencies ◽  
Damage Identification ◽  
Wavelet Packet ◽  
Wavelet Packet Transform ◽  
Engineering Structures ◽  
Numerical Examples ◽  
Frequency Responses ◽  
Stiffness Reduction ◽  
Index Curve

Damage identification is of tremendous significance in engineering structures. One key issue in damage identification is to determine an index that is sensitive to the structural damage. Current damage identification indices are generally focused on dynamic characteristics such as the natural frequencies, modal shapes, frequency responses, or their mathematical combinations. In this study, based on the wavelet packet transform, we propose a novel index, the energy curvature difference (ECD) index, to identify the damage in structures. The ECD index is the summation of component energy curvature differences after a signal is decomposed using WPT. Moreover, two numerical examples are used to demonstrate the feasibility and validity of the proposed ECD index for damage identification. Stiffness reduction is employed to simulate the structural damage. The damage can be identified by the ECD index curve plot. The results of the examples indicate that the proposed ECD index is sensitive to low damage levels because even 5% stiffness reduction can be apparently identified. The proposed ECD index can be employed to effectively identify structural damage.

scholarly journals A weighted dual criterion for stochastic equivalent linearization method

2014 ◽  
Vol 36 (4) ◽  
pp. 307-320 ◽  
Author(s):  
N. D. Anh ◽  
N. N. Linh
Keyword(s):  
Piecewise Linear ◽  
Least Square Method ◽  
Piecewise Linear Function ◽  
Random Excitation ◽  
Linearization Method ◽  
Least Square ◽  
Weighting Coefficient ◽  
Equivalent Linearization ◽  
Mean Square ◽  
Equivalent Linearization Method

A weighted dual mean square criterion for stochastic equivalent linearization method is considered in which the forward and backward replacements are weighted. The normalized weighting coefficient is suggested as a piecewise linear function of the squared correlation coefficient and is defined by the least square method based on the data of Lutes-Sarkani oscillator. The application to two typical nonlinear systems subjected to random excitation shows accurate approximations when the nonlinearity varies from the weak to strong levels.

Experimental Verification of the Structural Damage Identification Method Developed for Beam Structures

2006 ◽  
Vol 326-328 ◽  
pp. 1113-1116
Author(s):  
Deokki Youn ◽  
Usik Lee ◽  
Oh Yang Kwon
Keyword(s):  
Experimental Verification ◽  
Structural Damage ◽  
Natural Frequencies ◽  
Damage Identification ◽  
Mode Shapes ◽  
Damage State ◽  
Intact State ◽  
Identification Method ◽  
Structural Damage Identification ◽  
Cantilevered Beam

In this paper, an experimental verification has been conducted for a frequency response function (FRF)-based structural damage identification method (SDIM) proposed in the previous study [1]. The FRF-based SDIM requires the natural frequencies and mode shapes measured in the intact state and the FRF-data measured in the damaged state. Experiments are conducted for the cantilevered beam specimens with one and three slots. It is shown that the proposed FRF-based SDIM provides damage identification results that agree quite well with true damage state.

scholarly journals AVALIAÇÃO DA POTENCIALIDADE DE FUNÇÕES OBJETIVO UTILIZADAS NA IDENTIFICAÇÃO DE FALHAS EM ESTRUTRAS TRELIÇADAS

2017 ◽  
Vol 13 (2) ◽  
Author(s):  
Marcus Alexandre Noronha de Brito ◽  
Luiano Mendes Bezerra ◽  
Willian Taylor Matias Silva ◽  
Wellington Andrade da Silva
Keyword(s):  
Structural Damage ◽  
Lattice Structure ◽  
Optimal Solution ◽  
Least Square Method ◽  
Least Square ◽  
Objective Functions ◽  
Residual Function ◽  
Internal Damage ◽  
Damage Location ◽  
Natural Modes

RESUMO: A realização da análise de um conjunto de “Assinaturas Estruturais” ou comumente denominadas como “Funções Objetivo” possibilita o conhecimento de suas respectivas potencialidades ou sensibilidades em identificar falhas ou danos estruturais. Cinco Funções Objetivo são avaliadas neste trabalho compostas por grandezas estáticas, deslocamentos, e dinâmicas, como modos e frequências naturais de vibração, de modo a unir a simplicidade de obtenção dos parâmetros estáticos com a potencialidade das características dinâmicas. Ainda se observa que a otimização destas soluções pela minimização de uma função residual com a aplicação de um processo combinatório, juntamente com o Método dos Mínimos Quadrados – MMQ resulta na localização e quantificação de falhas ou danos internos nas barras de uma estrutura treliçada. Dessa forma, avalia-se a sensibilidade das Funções Objetivo na captura dos danos propostos determinando assim a Função que apresenta a solução ótima para o problema estrutural apresentado de localização de dano possibilitando também a observação das dificuldades encontradas nestes problemas. Dessa forma os resultados expostos evidenciam a capacidade das “Funções Objetivo” estudadas em auxiliar ações de análise de localização de danos estruturais internos, reduzindo a aplicação de métodos como ultrassom a locais mais restritos, caso necessário. ABSTRACT: The analysis of a set of "structural signatures" or also called "Objective Functions" enables the knowledge of their respective capabilities or sensitivities to identify flaws or structural damage. Five objective functions are evaluated in this work comprised of static quantities, offsets and processes as natural modes and frequencies of vibration, so as to combine the simplicity of obtaining static parameters with the capability of dynamic characteristics. Still noted that optimization of these solutions by minimizing a residual function with the application of a combinatorial procedure with the least square method - resulting in MMQ location and quantification of failures or internal damage to the bars of a lattice structure. Thus, it evaluates the sensitivity of the functions goal in the capture of the proposed damage thus determining the function that provides the optimal solution to the problem presented structural damage location also enables the observation of the difficulties encountered these problems. Thus, the results show the ability of the "Objective Functions" studied to assist in the analysis of the location of internal structural damage, reducing the application of methods such as ultrasound to more restricted locations, if necessary.

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