Ambient vibration based modal identification of a flexible retaining wall

Modal Identification is considered from response data of structural systems under nonstationary ambient vibration. The conventional autoregressive moving average (ARMA) algorithm is applicable to perform modal identification, however, only for stationary-process vibration. The ergodicity postulate which has been conventionally employed for stationary processes is no longer valid in the case of nonstationary analysis. The objective of this paper is therefore to develop modal-identification techniques based on the nonstationary time series for linear systems subjected to nonstationary ambient excitation. Nonstationary ARMA model with time-varying parameters is considered because of its capability of resolving general nonstationary problems. The parameters of moving averaging (MA) model in the nonstationary time-series algorithm are treated as functions of time and may be represented by a linear combination of base functions and therefore can be used to solve the identification problem of time-varying parameters. Numerical simulations confirm the validity of the proposed modal-identification method from nonstationary ambient response data.

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Modal Identification from Nonstationary Ambient Vibration Data Using Random Decrement Algorithm

Topics in Modal Analysis I, Volume 5 - Conference Proceedings of the Society for Experimental Mechanics Series ◽

10.1007/978-1-4614-2425-3_20 ◽

2012 ◽

pp. 223-232

Author(s):

Chang-Sheng Lin ◽

Dar-Yun Chiang

Keyword(s):

Modal Identification ◽

Ambient Vibration ◽

Vibration Data ◽

Random Decrement ◽

Nonstationary Ambient Vibration

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Automated band selection for Bayesian FFT modal identification Based on RetinaNet

Journal of Physics Conference Series ◽

10.1088/1742-6596/2078/1/012058 ◽

2021 ◽

Vol 2078 (1) ◽

pp. 012058

Author(s):

Chen Wang ◽

Zhilin Xue ◽

Yipeng Su ◽

Binbin Li

Keyword(s):

Operation Time ◽

Modal Identification ◽

Ambient Vibration ◽

Mode Shapes ◽

Band Selection ◽

Data Sets ◽

Civil Structures ◽

Frequency Bands ◽

Operational Conditions ◽

Vibration Data

Abstract Bayesian FFT algorithm is a popular method to identify modal parameters, e.g., modal frequencies, damping ratios, and mode shapes, of civil structures under operational conditions. It is efficient and provides the identification uncertainty in terms of posterior distribution. However, in utilizing the Bayesian FFT algorithm, it is tedious to manually select frequency bands and initial frequencies. This step requires professional knowledge and costs most of time, which prevents the automation of Bayesian FFT algorithm. Regarding the band selection as an object detection problem, we design a band selection network based on the RetinaNet to automatically select frequency bands and a peak prediction network to predict the initial frequencies. The designed networks are trained using the singular value spectrum of measured ambient vibration data and verified by various data sets. It can achieve the human accuracy with much less operation time, and thus provides a corner stone for the automation of Bayesian FFT algorithm.

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Seismic behavior of an inverted T-shape flexible retaining wall via dynamic centrifuge tests

Bulletin of Earthquake Engineering ◽

10.1007/s10518-013-9558-9 ◽

2013 ◽

Vol 12 (2) ◽

pp. 961-980 ◽

Cited By ~ 15

Author(s):

Seong-Bae Jo ◽

Jeong-Gon Ha ◽

Mintaek Yoo ◽

Yun Wook Choo ◽

Dong-Soo Kim

Keyword(s):

Seismic Behavior ◽

Retaining Wall ◽

Centrifuge Tests ◽

Flexible Retaining Wall

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Seismic Analysis of Soil Nailed Wall Using Finite Element Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.535-537.2027 ◽

2012 ◽

Vol 535-537 ◽

pp. 2027-2031 ◽

Cited By ~ 1

Author(s):

Jian Chun Wu ◽

Rong Shi

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Seismic Analysis ◽

Retaining Wall ◽

Plastic Behavior ◽

Soil Nailing ◽

Nonlinear Fem ◽

Elastic Plastic ◽

Flexible Retaining Wall ◽

Element Method

Using dynamic elastic-plastic finite element method, on the base of works together and interaction between loess and flexible retaining wall, 3-D nonlinear FEM (ADINA) is used to analyze and discussed the dynamic response of slope protected by soil nailing retaining wall under the EL-Centro and man-made Lanzhou accelerogram. A model that is capable of simulating the nonlinear static and dynamic elastic-plastic behavior of soil is used to model the soil, and a bilinear elastic-plastic model that has hardening behavior is used to model the soil nailing. Friction-element is employed to describe the soil-structure interaction behavior.The results show that the method is safe and credible. The results of the FEM dynamic analysis can be a useful reference for engineers of the design and construction of the soil nailed wall.

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Extending Blind Modal Identification to the Underdetermined Case for Ambient Vibration

Volume 12: Vibration, Acoustics and Wave Propagation ◽

10.1115/imece2012-93140 ◽

2012 ◽

Cited By ~ 5

Author(s):

Scot McNeill

Keyword(s):

Natural Frequencies ◽

Second Order ◽

Modal Identification ◽

Ambient Vibration ◽

Mode Shapes ◽

Frequency Domain Method ◽

Blind Identification ◽

Vibration Data ◽

Modal Damping ◽

Six Dof

The modal identification framework known as Blind Modal Identification (BMID) has recently been developed, drawing on techniques from Blind Source Separation (BSS). Therein, a BSS algorithm known as Second Order Blind Identification (SOBI) was adapted to solve the Modal IDentification (MID) problem. One of the drawbacks of the technique is that the number of modes identified must be less than the number of sensors used to measure the vibration of the equipment or structure. In this paper, an extension of the BMID method is presented for the underdetermined case, where the number of sensors is less than the number of modes to be identified. The analytic signal formed from measured vibration data is formed and the Second Order Blind Identification of Underdetermined Mixtures (SOBIUM) algorithm is applied to estimate the complex-valued modes and modal response autocorrelation functions. The natural frequencies and modal damping ratios are then estimated from the corresponding modal auto spectral density functions using a simple Single Degree Of Freedom (SDOF), frequency-domain method. Theoretical limitations on the number of modes identified given the number of sensors are provided. The method is demonstrated using a simulated six DOF mass-spring-dashpot system excited by white noise, where displacement at four of the six DOF is measured. All six modes are successfully identified using data from only four sensors. The method is also applied to a more realistic simulation of ambient building vibration. Seven modes in the bandwidth of interest are successfully identified using acceleration data from only five DOF. In both examples, the identified modal parameters (natural frequencies, mode shapes, modal damping ratios) are compared to the analytical parameters and are demonstrated to be of good quality.

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The stability of the Corrugated Concrete Sheet Pile (CCSP) of the Soil Retaining Wall at the Abutmen Bridge Bh 1751 in Lok Ulo District, Kebumen

Jurnal Perkeretaapian Indonesia ◽

10.37367/jpi.v3i1.72 ◽

2018 ◽

Vol 3 (1) ◽

Author(s):

Septiana Widi Astuti ◽

Ayu Prativi

Keyword(s):

Rolling Force ◽

Retaining Wall ◽

Earth Pressure ◽

Deep Excavation ◽

Safety Requirements ◽

Lateral Earth Pressure ◽

Bridge Abutment ◽

Excavation Work ◽

The Stability ◽

Flexible Retaining Wall

Abutment bridge is a building under the bridge located on both sides of the bridge end. The process of building a bridge abutment often requires excavation to the depth of the abutment base so that the abutment reinforcement and casting work can be carried out. In deep excavation work, each side of the excavation needs to be installed in a flexible retaining wall type (plaster) first. In this study, CCSP stability analysis was carried out on earth excavation work for abutment bridge BH 1751. The calculation method starts from determining the lateral earth pressure acting on the soil, then determining the depth of CCSP planting that is able to produce CCSP stability on the rolling force. The analysis shows that the depth of CCSP planting that meets the safety requirements of the rolling force is 20 m

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DETERMINATION OF THE EFFECT OF TiO2 ON THE DYNAMIC BEHAVIOR OF SCALED CONCRETE CHIMNEY BY OMA

Materiali in tehnologije ◽

10.17222/mit.2021.059 ◽

2021 ◽

Vol 55 (3) ◽

Author(s):

Sertaç Tuhta ◽

Furkan Günday

Keyword(s):

Titanium Dioxide ◽

Outer Surface ◽

Ground Level ◽

Modal Identification ◽

Ambient Vibration ◽

Mode Shapes ◽

Dynamic Parameters ◽

Vibration Data ◽

Output Only ◽

Frequency Domain Decomposition

In this article, the dynamic parameters (frequencies, mode shapes, damping ratios) of a scaled concrete chimney and the dynamic parameters (frequencies, mode shapes, damping ratios) of the entire outer surface of the 80-micron-thick titanium dioxide are compared using the operational modal analysis method. Ambient excitation was provided from micro tremor ambient vibration data at ground level. Enhanced Frequency Domain Decomposition (EFDD) is used for the output-only modal identification. From this study, very best correlation is found between the mode shapes. Titanium dioxide applied to the entire outer surface of the scaled concrete chimney has an average of 16.34 % difference in frequency values and 9.81 % in damping ratios, proving that nanomaterials can be used to increase the rigidity in chimneys, in other words, for reinforcement. Another important result determined in the study is that it has been observed that the adherence of titanium dioxide and similar nanomaterials mentioned in the introduction to concrete chimney surfaces is at the highest level.

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