Study on applicability of two modal identification techniques in irrelevant cases

Tomaszewska, Agnieszka; Szafrański, Marek

doi:10.1007/s43452-020-0014-8

Cited by 7 publications

(6 citation statements)

References 26 publications

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“…The damping ratios cannot be identified, which is the method’s limitation. The practical applications of the PP-CA technique are addressed in, e.g., [ 11 , 12 , 13 ].…”

Section: Methodsmentioning

confidence: 99%

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Material Parameters Identification of Historic Lighthouse Based on Operational Modal Analysis

2020

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In the present paper, the identification of the material parameters of a masonry lighthouse is discussed. A fully non-invasive method was selected, in which the material properties were determined via numerical model validation applied to the first pair of natural frequencies and their related mode shapes, determined experimentally. The exact structural model was built by means of the finite element method. To obtain experimental data for the inverse analysis, operational modal analysis was applied to the structure. Three methods were considered: peak picking (PP), eigensystem realization algorithm (ERA) and natural excitation technique with ERA (NExT-ERA). The acceleration’s responses to environmental excitations, enhanced in some periods of time by sheet piling hammering or by sudden interruptions like wind stroke, were assumed within the analysis input. Different combinations of the input were considered in the PP and NExT-ERA analysis to find the most reasonable modal forms. A number of time periods of a free-decay character were considered in the ERA technique to finally calculate the averaged modal forms. Finally, the elastic modulus, Poisson’s ratio and material density of brick, sandstone and granite masonry were determined. The obtained values supplement the state of the art database concerning historic building materials. In addition, the numerical model obtained in the analysis may be used in further cases of structural analysis.

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“…The damping ratios cannot be identified, which is the method’s limitation. The practical applications of the PP-CA technique are addressed in, e.g., [ 11 , 12 , 13 ].…”

Section: Methodsmentioning

confidence: 99%

“…Directly measured, short-time free-decay signals caused by blasts of wind or river undulations are considered as the input. A similar approach was applied in the paper [ 11 ], in which the ERA efficacy in the case of a massive masonry tower was studied.…”

Section: Methodsmentioning

confidence: 99%

Material Parameters Identification of Historic Lighthouse Based on Operational Modal Analysis

2020

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“…However, the peak of the frequency response shown in Figure 21 may not exactly correspond to the natural frequency. Therefore, the Eigensystem Realization Algorithm (ERA) [38] is used to calculate the natural frequencies of each virtual structure, which are shown in Table 7. Via ERA, structural modal information can be solved by impulse response.…”

Section: Natural Frequencies Estimation Of the Virtual Structuralmentioning

confidence: 99%

Damage Identification of Semi-Rigid Joints in Frame Structures Based on Additional Virtual Mass Method

Zhang

et al. 2022

Sensors

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In civil engineering, the joints of structures are complex, and their damage is generally hard to be detected. Due to the insensitivity of structural modal information to local joint damage, this paper presents a method based on additional virtual mass for damage identification of a semi-rigid joint in a frame structure. Firstly, the modeling of a semi-rigid is described. Secondly, the frequency response of the virtual structure is constructed, and the natural frequency of the constructed virtual structure is extracted by the ERA method. By adding multiple values of virtual masses at different positions, the natural frequency information sensitive to joint damage for damage identification is effectively increased. Based on the above theory, qualitative identification of joint damage is proposed to detect the potential damage, and identification of both damage location and its extent is presented, using natural frequency. Improved Orthogonal Matching Pursuit (IOMP) algorithm is employed to improve the accuracy of the natural frequency-based method for damage identification. At last, numerical simulation of a three-story frame is performed to discuss and to verify the effectiveness of the proposed method.

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“…The first of them was based on the correlation between input data, excitations; and output data, responses of the structure [34][35][36]. The second one, called the operational modal analysis (OMA) or ambient modal analysis, was based solely on output data [37][38][39]. There are many methods for the identification of dynamic parameters of structures.…”

Section: Introductionmentioning

confidence: 99%

“…A good review of the literature on modal identification techniques can be found in [39,45,46]. Furthermore, in the literature [38,39,[47][48][49], a comparison of the dynamic parameters identification carried out by various methods could be found.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Study on Dynamics of Two Footbridges with Different Shapes of Girders

Banaś

Jankowski

2020

Applied Sciences

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The paper presents the experimental and numerical results of the dynamic system identification and verification of the behavior of two footbridges in Poland. The experimental part of the study involved vibration testing under different scenarios of human-induced load, impulse load, and excitations induced by vibration exciter. Based on the results obtained, the identification of dynamic parameters of the footbridges was performed using the peak-picking method. With the impulse load applied to both structures, determination of their natural vibration frequencies was possible. Then, based on the design drawings, detailed finite element method (FEM) models were developed, and the numerical analyses were carried out. The comparison between experimental and numerical results obtained from the modal analysis showed a good agreement. The results also indicated that both structures under investigation have the first natural bending frequency of the deck in the range of human-induced excitation. Therefore, the risk of excessive structural vibrations caused by pedestrian loading was then analysed for both structures. The vibration comfort criteria for both footbridges were checked according to Sétra guidelines. In the case of the first footbridge, the results showed that the comfort criteria are fulfilled, regardless of the type of load. For the second footbridge, it was emphasized that the structure meets the assumptions of the guidelines for vibration severability in normal use; nevertheless, it is susceptible to excitations induced by synchronized users, even in the case of a small group of pedestrians.

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Study on applicability of two modal identification techniques in irrelevant cases

Cited by 7 publications

References 26 publications

Material Parameters Identification of Historic Lighthouse Based on Operational Modal Analysis

Material Parameters Identification of Historic Lighthouse Based on Operational Modal Analysis

Damage Identification of Semi-Rigid Joints in Frame Structures Based on Additional Virtual Mass Method

Experimental and Numerical Study on Dynamics of Two Footbridges with Different Shapes of Girders

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