scholarly journals Output-Only Damage Detection of Shear Building Structures Using an Autoregressive Model-Enhanced Optimal Subpattern Assignment Metric

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 2050
Author(s):  
Liu Mei ◽  
Huaguan Li ◽  
Yunlai Zhou ◽  
Dawang Li ◽  
Wujian Long ◽  
...  
Keyword(s):  
Dynamic Systems ◽  
Autoregressive Model ◽  
Structural Damage ◽  
Damping Ratio ◽  
Autoregressive Models ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Building Structures ◽  
Output Only ◽  
Shear Building

This paper proposes a novel output-only structural damage indicator by incorporating the pole-based optimal subpattern assignment distance with autoregressive models to localize and relatively assess the severity of damages for sheared structures. Autoregressive models can model dynamic systems well, while their model poles can represent the state of the dynamic systems. Structural damage generally causes changes in the dynamic characteristics (especially the natural frequency, mode shapes and damping ratio) of structures. Since the poles of the autoregressive models can solve the modal parameters of the structure, the poles have a close relationship with the modal parameters so that the changes in the poles of its autoregressive model reflect structural damages. Therefore, we can identify the damage by tracking the shifts in the dynamic system poles. The optimal subpattern assignment distance, which is the performance evaluator in multi-target tracking algorithms to measure the metric between true and estimated tracks, enables the construction of damage sensitive indicator from system poles using the Hungarian algorithm. The proposed approach has been validated with a five-story shear-building using numerical simulations and experimental verifications, which are subjected to excitations of white noise, El Centro earthquake and sinusoidal wave with frequencies sweeping, respectively; the results indicate that this approach can localize and quantify structural damages effectively in an output-only and data-driven way.

scholarly journals Changes in the Dynamic Characteristics of a Small-Scale Gymnasium Model Due to Simulated Earthquake Damage

2021 ◽  
Vol 16 (7) ◽  
pp. 1074-1085
Author(s):  
Jun Fujiwara ◽  
Akiko Kishida ◽  
Takashi Aoki ◽  
Ryuta Enokida ◽  
Koichi Kajiwara ◽  
...  
Keyword(s):  
Structural Damage ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Small Scale ◽  
Building Structures ◽  
Shake Table Tests ◽  
Large Span ◽  
Similarity Rule ◽  
Measured Response

In this study, the authors used shake-table tests to assess the modal parameters of a small-scale gymnasium model with simulated damage, the feasibility of estimating the damage to large-span building structures was studied. In Japan, large-span structures, such as gymnasiums, are expected to be used as evacuation shelters when a natural disaster occurs. As the shelter itself may be damaged in case of an earthquake, it is critical to determine whether damage has occurred, where it occurred, and how serious it is, before the shelter is used. The small-scale gymnasium was designed based on the similarity rule. Observed earthquake ground motions scaled to aftershock levels were applied to the model. The natural frequencies and mode shapes were obtained from the measured response accelerations. To study the influence of structural damage on the modal parameters, a gymnasium model with simulated damage was also tested. The results indicate that the modal parameters, e.g., natural frequencies and mode shapes, can be obtained from the response accelerations, and the damage patterns can be estimated from the changes in these modal parameters.

scholarly journals Time-Varying Wind Load Identification Based on Minimum-Variance Unbiased Estimation

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Huili Xue ◽  
Kun Lin ◽  
Yin Luo ◽  
Hongjun Liu
Keyword(s):  
Damping Ratio ◽  
Estimation Method ◽  
Minimum Variance ◽  
Wind Load ◽  
Ar Model ◽  
Unbiased Estimation ◽  
Recursive Identification ◽  
Time Varying ◽  
Building Structures ◽  
Shear Building

A minimum-variance unbiased estimation method is developed to identify the time-varying wind load from measured responses. The formula derivation of recursive identification equations is obtained in state space. The new approach can simultaneously estimate the entire wind load and the unknown structural responses only with limited measurement of structural acceleration response. The fluctuating wind speed process is investigated by the autoregressive (AR) model method in time series analysis. The accuracy and feasibility of the inverse approach are numerically investigated by identifying the wind load on a twenty-story shear building structure. The influences of the number and location of accelerometers are examined and discussed. In order to study the stability of the proposed method, the effects of the errors in crucial factors such as natural frequency and damping ratio are discussed through detailed parametric analysis. It can be found from the identification results that the proposed method can identify the wind load from limited measurement of acceleration responses with good accuracy and stability, indicating that it is an effective approach for estimating wind load on building structures.

scholarly journals Influence of Crack on Modal Parameters of Cantilever Beam Using Experimental Modal Analysis

2018 ◽  
Vol 1 (1) ◽  
pp. 16-23 ◽  
Author(s):  
Siva Sankara Babu Chinka ◽  
Balakrishna Adavi ◽  
Srinivasa Rao Putti
Keyword(s):  
Numerical Analysis ◽  
Modal Analysis ◽  
Natural Frequency ◽  
Cantilever Beam ◽  
Damping Ratio ◽  
Crack Depth ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Crack Location

In this paper, the dynamic behavior of a cantilever beam without and with crack is observed. An elastic Aluminum cantilever beams having surface crack at various crack positions are considered to analyze dynamically. Crack depth, crack length and crack location are the foremost parameters for describing the health condition of beam in terms of modal parameters such as natural frequency, mode shape and damping ratio. It is crucial to study the influence of crack depth and crack location on modal parameters of the beam for the decent performance and its safety. Crack or damage of structure causes a reduction in stiffness, an intrinsic reduction in resonant frequencies, variation of damping ratios and mode shapes. The broad examination of cantilever beam without crack and with crack has been done using Numerical analysis (Ansys18.0) and experimental modal analysis. To observe the exact higher modes of beam, discretize the beam into small elements. An experimental set up was established for cantilever beam having crack and it was excited by an impact hammer and finally the response was obtained using PCB accelerometer with the help sound and vibration toolkit of NI Lab-view. After obtaining the Frequency response functions (FRFs), the natural frequencies of beam are estimated using peak search method. The effectiveness of experimental modal analysis in terms of natural frequency is validated with numerical analysis results. This paper contains the study of free vibration analysis under the influence of crack at different points along the length of the beam.

The Comparative Modal Analysis of Simulation and Experiment on the Electronic Button-Sewing Machine Shell

2013 ◽  
Vol 668 ◽  
pp. 612-615
Author(s):  
Li Zhang ◽  
Guang Yuan Nie ◽  
Hong Wu ◽  
Jie Chen
Keyword(s):  
Comparative Analysis ◽  
Modal Analysis ◽  
Natural Frequency ◽  
Mode Shape ◽  
Damping Ratio ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Ansys Software ◽  
Sewing Machine ◽  
Simulation And Experiment

In this paper, the simulation with ANSYS software and the experimental modal analysis by impacting are carried out on the electronic button-sewing machine shell. The modal parameters, such as the natural frequency, the damping ratio and the mode shape, are obtained. Comparative analysis of their results shows that the mode shapes of the machine shell are mainly the outward-expanding and inward-contracting vibrations, which provides a useful reference for vibration and noise reduction of the electronic button-sewing machine.

scholarly journals Operational modal analysis using lifted continuously scanning laser Doppler vibrometer measurements and its application to baseline-free structural damage identification

2019 ◽  
Vol 25 (7) ◽  
pp. 1341-1364 ◽  
Author(s):  
Y.F. Xu ◽  
Da-Ming Chen ◽  
W.D. Zhu
Keyword(s):  
Structural Damage ◽  
Damage Identification ◽  
Laser Doppler Vibrometer ◽  
Laser Doppler ◽  
Scanning Laser ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Experimental Investigations ◽  
Scanning Laser Doppler Vibrometer ◽  
White Noise Excitation

A continuously scanning laser Doppler vibrometer (CSLDV) system is capable of efficient and spatially dense vibration measurements by sweeping its laser spot along a scan path assigned on a structure. This paper proposes a new operational modal analysis (OMA) method based on a data processing method for CSLDV measurements of a structure, called the lifting method, under white-noise excitation and applies a baseline-free method to identify structural damage using estimated mode shapes from the OMA method. The lifting method enables transformation of raw CSLDV measurements into measurements at individual virtual measurement points, as if the latter were made by use of an ordinary scanning laser Doppler vibrometer in a step-wise manner. It is shown that a correlation function with nonnegative time delays between lifted CSLDV measurements at two virtual measurement points on a structure under white-noise excitation and its power spectrum contain modal parameters of the structure, that is, natural frequencies, modal damping ratios, and mode shapes. The modal parameters can be estimated by using a standard OMA algorithm. A major advantage of the proposed OMA method is that curvature mode shapes associated with mode shapes estimated by the method can reflect local anomaly caused by small-sized structural damage, while those estimated by other existing OMA methods that use CSLDV measurements cannot. Numerical and experimental investigations are conducted to study the OMA method and baseline-free structural damage identification method. In the experimental investigation, effects of the scan frequency of a CSLDV system on the two methods were studied. It is shown in both the numerical and experimental investigations that modal parameters can be accurately estimated by the OMA method and structural damage can be successfully identified in neighborhoods with consistently high values of curvature damage indices.

scholarly journals The use of modal parameters in structural health monitoring

2018 ◽  
Vol 162 ◽  
pp. 04020
Author(s):  
Ali Al-Ghalib ◽  
Fouad Mohammad
Keyword(s):  
Structural Health Monitoring ◽  
Natural Frequency ◽  
Health Monitoring ◽  
Damping Ratio ◽  
Reinforced Concrete Beams ◽  
Modal Testing ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Structural Health ◽  
Vibration Parameters

The concrete is liable to damage due to various stresses which compensate its adequacy and safety. The estimation of remaining strength in reinforced concrete beams when subjected to increased loading action utilizing vibration parameters is investigated. For this reason, three beams are loaded statically close to failure in various increasing load steps and then repaired. The beams are all of same dimensions, but are different in strength and range of defects introduced to each sample. Following each loading step, the experimental modal testing is utilized to collect the vibration parameters (natural frequency, damping ratio and mode shapes) of each beam when tested under free support boundary conditions. The use of vibration parameters for the purpose of damage identification are known to be an elaborate and lengthy process. On the other hand, they are successful for the structural health monitoring given that they are able to provide global on-site automated continuous monitoring. The paper features post analysis procedures for experimental modal measurements of three concrete samples to obtain and correlate the basic modal parameters (natural frequency, modal damping and mode shapes). The results of the extracted modal parameters and their combination are exploited in this research as quantified identification parameters. This paper concludes that modal parameters are successful in determining the location and quantity of structural degradation, when holistic approach considered through a system.

Modal Parameter Identification Method for Structural Health Monitoring Benchmark Model

2012 ◽  
Vol 594-597 ◽  
pp. 1113-1117
Author(s):  
Cheng Li ◽  
Ling Yu
Keyword(s):  
International Association ◽  
Damping Ratio ◽  
Combination Method ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Modal Parameter ◽  
Stochastic Subspace Identification ◽  
Identification Method ◽  
Modal Damping Ratio ◽  
American Society

Structural modal parameters can be identified using both output responses and input excitations or only using output responses of structures. When the input excitations are known, some frequency response functions (FRF) can be obtained and further used to accurately identify the modal frequencies and mode shapes of structures, but the identified modal damping ratio is often lack of reliability. Under ambient excitations, the peak picking method (PP) is often used to quickly identify the modal parameters of structures, but some vibration modes are missed sometimes, particularly when the dense modes or subjective errors may appear around the peaks picked. Modal parameters can be identified using the stochastic subspace identification method (SSI) based on statistical data, however, the SSI method easily produces false modes in practice. In order to compensate the deficiencies of SSI method, the PP and the SSI methods are combined to identify the modal parameters of the benchmark structure which proposed by the International Association for Structure Control and the task group of American Society Civil Engineers (IASC-ASCE) in this paper. The illustrated results show that this combination method can accurately identify the modal parameters of the benchmark structure with some application prospects.

A Global Damage Indicator Based on the Modal Parameters in the FE-Simulation of the Structures

2011 ◽  
Vol 250-253 ◽  
pp. 1105-1108 ◽  
Author(s):  
Sam Young Noh ◽  
Eun Mi Sin
Keyword(s):  
Structural Damage ◽  
Structural Integrity ◽  
Natural Frequencies ◽  
Frame Structure ◽  
Mode Shapes ◽  
Design Stage ◽  
Modal Parameters ◽  
Damage Analysis ◽  
Damage Indicator ◽  
Damage Simulation

The purpose of the study is the development of a tool for the prediction of the structural damage by means of the numerical damage simulation in the design stage. For the evaluation of the structural integrity in the numerical damage analysis, a global damage indicator was defined based on the modal parameters obtained from the tangential equation of motion: a set of natural frequencies and mode shapes. As they are given in a set, it may be difficult to treat them as a damage indicator. In this study a new damage indicator based on the natural frequencies was defined using the contribution factors of the mode shapes under consideration of the external modal energy. A numerical example of a frame structure showed the efficiency of the damage indicator defined in the study.

scholarly journals Structural Damage Detection Based on Modal Parameters Using Continuous Ant Colony Optimization

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Aditi Majumdar ◽  
Bharadwaj Nanda ◽  
Dipak Kumar Maiti ◽  
Damodar Maity
Keyword(s):  
Ant Colony Optimization ◽  
Structural Damage ◽  
Reduction Factor ◽  
Ant Colony ◽  
Modal Testing ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Ant Colony Optimization Algorithm ◽  
Stiffness Reduction ◽  
Wide Range

A method is presented to detect and quantify structural damages from changes in modal parameters (such as natural frequencies and mode shapes). An inverse problem is formulated to minimize the objective function, defined in terms of discrepancy between the vibration data identified by modal testing and those computed from analytical model, which then solved to locate and assess the structural damage using continuous ant colony optimization algorithm. The damage is formulated as stiffness reduction factor. The study indicates potentiality of the developed code to solve a wide range of inverse identification problems.

Sign in / Sign up

Export Citation Format

Share Document