Theory of un-scaled flexibility identification from output-only data

Zhang, Jian; Guo, S.L.; Chen, Xi

doi:10.1016/j.ymssp.2014.02.009

Cited by 16 publications

(9 citation statements)

References 24 publications

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“…Most of the existing methods processing ambient vibration data can only output basic modal parameters. This is because that the FRF magnitudes cannot be exactly estimated from ambient test data owing to the unknown input forces . However, the FRF magnitudes are important to the calculation of the mass‐normalized scaling factor, which is a function of modal mass.…”

Section: Unscaled Flexibility Identificationmentioning

confidence: 99%

“…When the input force is a Dirac delta function, the structural response is the IRF. The FRF of the structure is obtained by performing Fourier transform of its IRF

H_{oi} ((), ω) = \sum_{r = 1}^{n} ℶ_{oi}^{r} \int_{- \infty}^{+ \infty} italicexp ((), - ξ_{r} ω_{r} t - italicjωt) italicsin ((), ω_{dr} t) italicdt

where

ℶ_{oi}^{r} = ϕ_{or} ϕ_{ir} true/ M_{r} ω_{dr}

, ω r is the r th modal frequency, ξ r is the r th modal damping ratio, ϕ or and ϕ ir are the r th mode shape at nodes o and i , respectively, M r is the r th modal mass, and

ω_{dr} = ω_{r} \sqrt{1 - ξ_{r}^{2}}

is the r th damped natural frequency. In the impact test, FRF is estimated by using both the measured input forces and output responses.…”

Section: Unscaled Flexibility Identificationmentioning

confidence: 99%

“…However, the limitation of ambient vibration test is that it mainly outputs basic modal parameters, such as natural frequencies, damping ratios, and unscaled mode shapes, which are difficult to effectively support structural performance evaluation . The reason is that the ambient vibration test only outputs the frequency response function (FRF) shape rather than the magnitude; however, the FRF magnitude is important for deep‐level parameter identification …”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Ambient vibration test-based deflection prediction of a posttensioned concrete continuous box girder bridge

Tian

Zhang

2017

Struct Control Health Monit

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Summary Ambient vibration test generally only outputs basic modal parameters including frequencies, damping ratios, and unscaled mode shapes, which cannot directly support decision making of structural maintenance and management. In this article, structural deep‐level parameters including unscaled and scaled flexibility identification of a posttensioned concrete continuous box girder bridge are studied by performing ambient vibration test, which is able to predict structural deflections by multiplying the static load with the identified flexibility. Ambient vibration test of the bridge and basic modal identification are firstly performed. Then, the method of unscaled flexibility identification is proposed by investigating the relationship between the frequency response function estimated from ambient test data and the analytical one. Finally, a mass‐changing strategy is utilized to identify the scaled flexibility from output‐only data, in which the key issue is to identify mass‐normalized scaling factors by performing ambient vibration tests of tested structure before and after changing its mass. Numerical simulation of a simply supported beam and field test of a three‐span bridge has been conducted to verify the capability and reliability of the proposed method. The good agreement between the predicted deflections from the identified flexibility and those measured from the static test successfully illustrates the effectiveness of the proposed method.

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Section: Unscaled Flexibility Identificationmentioning

confidence: 99%

“…When the input force is a Dirac delta function, the structural response is the IRF. The FRF of the structure is obtained by performing Fourier transform of its IRF

H_{oi} ((), ω) = \sum_{r = 1}^{n} ℶ_{oi}^{r} \int_{- \infty}^{+ \infty} italicexp ((), - ξ_{r} ω_{r} t - italicjωt) italicsin ((), ω_{dr} t) italicdt

where

ℶ_{oi}^{r} = ϕ_{or} ϕ_{ir} true/ M_{r} ω_{dr}

, ω r is the r th modal frequency, ξ r is the r th modal damping ratio, ϕ or and ϕ ir are the r th mode shape at nodes o and i , respectively, M r is the r th modal mass, and

ω_{dr} = ω_{r} \sqrt{1 - ξ_{r}^{2}}

is the r th damped natural frequency. In the impact test, FRF is estimated by using both the measured input forces and output responses.…”

Section: Unscaled Flexibility Identificationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ambient vibration test-based deflection prediction of a posttensioned concrete continuous box girder bridge

Tian

Zhang

2017

Struct Control Health Monit

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“…Impact testing is a significant technique for structural‐condition assessment in SHM and it contains capabilities for rapid assessment and reliable diagnosis of bridges. Both structural responses and impact forces can be measured by impact testing, from which the structural frequency response function (FRF), including its magnitudes and shapes, can be computed, whereas only shapes of FRF can be obtained from the ambient vibration test (Zhang et al., ). However, the magnitudes of FRF are extremely important for the identification of structural parameters such as scaling factors and flexibility matrix.…”

Section: Introductionmentioning

confidence: 99%

Rapid Impact Testing and System Identification of Footbridges Using Particle Image Velocimetry

Tian

Zhang

2018

Computer aided Civil Eng

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The rapid impact testing of bridges contains unique advantages. For example, structural parameters, including frequency response function and structural flexibility matrix can be identified; however, additional impact-testing instruments are required to excite a bridge, restricting the efficiency of the measurement strategy in terms of experimental cost and time. In this paper, a particle image velocimetry-based method is proposed for the rapid impact testing and system identification of footbridges under pedestrian excitations. The proposed method has shown promising features: (1) pedestrian load is utilized for the impact excitation of footbridges, which is more convenient than the conventional impacttesting method with additional excitation devices; (2) the human-induced impact forces under varying jumping scenarios are calculated from image sequences of human motions acquired by a single camera with its noncontact and target-less characteristics; and (3) both humaninduced impact forces (inputs) and structural responses (outputs) are employed to identify more modal parameters (i.e., scaling factors, modal mass, and structural flexibility). The robustness of the proposed method was successfully validated by a laboratory test of a simply supported beam and field testing of a cable-stayed footbridge. The proposed method not only could improve

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“…Zhang et al. () proved that the impact test method with collecting force data has the advantage of identifying the magnitudes of structural frequency response functions (FRFs), and which are necessary for structural flexibility identification. However, the limitation of the traditional impact test method lies in that it requires a large number of sensors deployed on the entire structure, which usually leads to expensive experimental costs.…”

Section: Introductionmentioning

confidence: 99%

A Quantum‐Inspired Genetic Algorithm‐Based Optimization Method for Mobile Impact Test Data Integration

Zhao

Guo

Zhou

et al. 2018

Computer aided Civil Eng

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The traditional impact test method needs a large number of sensors deployed on the entire structure, which cannot meet the requirements of rapid bridge testing. A new mobile impact test method is proposed by sequentially testing the substructures then integrating the test data of all substructures for flexibility identification of the entire structure. The novelty of the proposed method is that the quantum-inspired genetic algorithm (QIGA) is proposed to improve computational efficiency by transforming the scaling factor sign determination problem to an optimization problem. Experimental example of a steel-concrete composite slab and numerical example of a three-span continuous rigid-frame bridge are studied which successfully verify the effectiveness of the proposed method. C 2018 Computer-Aided Civil and Infrastructure Engineering.

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Theory of un-scaled flexibility identification from output-only data

Cited by 16 publications

References 24 publications

Ambient vibration test-based deflection prediction of a posttensioned concrete continuous box girder bridge

Ambient vibration test-based deflection prediction of a posttensioned concrete continuous box girder bridge

Rapid Impact Testing and System Identification of Footbridges Using Particle Image Velocimetry

A Quantum‐Inspired Genetic Algorithm‐Based Optimization Method for Mobile Impact Test Data Integration

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