• Title/Summary/Keyword: damage estimation

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Damage Estimation Technique of a Structure Using Committee of Neural Networks (군집 신경망기법을 이용한 구조물 손상추정기법)

  • Lee, Jong-Won
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.28 no.10
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    • pp.47-54
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    • 2012
  • In this study, committee technique for neural networks is applied to damage estimation of structure to enhance estimation result of single neural network. Local minima sensitive to initial synaptic weights and non-uniqueness of solution due to noise and limited number of measurements may be resolved by employing the committee technique, which is a statistical approach averaging damage indices in functional space. First, a numerical study for a simple beam was carried out. Damage locations and severities of the simple beam were reasonably estimated using change of modal parameters due to damage and committee of neural networks, and the estimation results of the single neural network could be effectively enhanced by applying the committee technique. The precedent damage estimation results for a cantilever beam using static and dynamic strain data from the distributed fiber optic sensor and the single neural network could also be considerably improved by applying the committee technique for neural networks.

A Preliminary Study of the Seismic Damage Estimation for Harbor Sites (항만 구역 지진피해예측 평가방안에 관한 예비 연구)

  • Choi, Seung-Ho;Kim, Han-Saem;Yoo, Seung-Hoon;Chung, Chung-Ki;Jang, In-Sung
    • Journal of the Earthquake Engineering Society of Korea
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    • v.15 no.3
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    • pp.45-55
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    • 2011
  • In this study, the state of the art and characteristics of major Korean port structures were investigated and analyzed. Damage of port structures during earthquakes, evaluation systems of seismic damage and seismic designs have also been investigated. Based on the research, a methodology of seismic damage estimation was proposed considering geotechnical information and the characteristics of the fragility of port structures.

Damage Estimation Method for Monopile Support Structure of Offshore Wind Turbine (모노파일 형식 해상풍력발전기 지지구조물의 손상추정기법)

  • Kim, Sang-Ryul;Lee, Jong-Won;Kim, Bong-Ki;Lee, Jun-Shin
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.7
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    • pp.667-675
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    • 2012
  • A damage estimation method for support structure of offshore wind turbine using modal parameters is presented for effective structural health monitoring. Natural frequencies and mode shapes for a support structure with monopile of an offshore wind turbine were calculated considering soil condition and added mass. A neural network was learned based on training patterns generated by the changes of natural frequency and mode shape due to various damages. Natural frequencies and mode shapes for 10 prospective damage cases were input to the trained neural network for damage estimation. The identified damage locations and severities agreed reasonably well with the accurate damages. Multi-damage cases could also be successfully estimated. Enhancement of estimation result using another parameters as input to neural network will be carried out by further study. Proposed method could be applied to other type of support structure of offshore wind turbine for structural health monitoring.

Damage Estimation of Structures Incorporating Structural Identification (동특성 추정을 이용한 구조물의 손상도 추정)

  • Yun, Chung-Bang;Lee, Hyeong-Jin;Kim, Doo-Ki
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1995.04a
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    • pp.136-143
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    • 1995
  • The problem of the structural identification becomes important, particularly with relation to the rapid increase of the number of the damaged or deteriorated structures, such as highway bridges, buildings, and industrial facilities. This paper summarizes the recent studies related to those problems by the present authors. The system identfication methods are generally classified as the time domain and the frequency domain methods. As time doamin methods, the sequential algorithms such as the extended Kalman filter and the sequential prediction error method are studied. Several techniques for improving the convergences are incorporated. As frequency domain methods, a new frequency response function estimator is introduced. For damage estimation of existing structures, the modal perturbation and the sensitivity matrix methods are studied. From the example analysis, it has been found that the combined utilization of the measurement data for the static response and the dynamic (modal) properties are very effictive for the damage estimation.

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Damage Detection for Bridges Considering Modeling Errors (모델링 오차를 고려한 교량의 손상추정)

  • 윤정방;이종재;이종원;정희영
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2002.04a
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    • pp.300-307
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    • 2002
  • Damage estimation methods are classified into two groups according to the dependence on the FE model : signal-based and model-based methods. Signal-based damage estimation methods are generally appropriate for detection of damage location, whereas not effective for estimation of damage severities. Model-based damage estimation methods are difficult to apply directly to the structures with a large number of the probable damaged members. It is difficult to obtain the exact model representing the real bridge behavior due to the modeling errors. The modeling errors even may exceed the modal sensitivity on damage. In this study, Model-based damage detection method which can effectively consider the modeling errors is suggested. Two numerical example analyses on a simple beam and a multi-girder bridge are presented to demonstrate the effectiveness of the presented method.

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A Study on the Damage Estimation of CFRP using Acoustic Emission (음향방출을 이용한 탄소섬유강화 플라스틱의 손상 평가에 관한 연구)

  • 이장규;박성완;김봉각
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2003.10a
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    • pp.307-312
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    • 2003
  • The object of this study is to investigate a damage estimation of single edge cracked tensile specimens ($2_a$/W) as a function of acoustic emission (AE) according to the unidirectionally oriented carbon/epoxy composites, CFRP AE signals were analyzed and classified 3 regions by event counts, energy and amplitude for coressponding applied load. On tensile loading and using the results of the AE analysis, it was found that the event counts, cumulative counts or energy, and amplitude distributions useful for the prediction of damage failure.

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Building Response to Excavation-Induced Ground Movements and Damage Estimation (굴착유발 지반변위에 의한 인접구조물의 거동 및 손상도 예측)

  • Son, Moo-Rak;Cording, E.J.
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.249-256
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    • 2006
  • New infrastructures and buildings are being constructed increasingly in congested urban areas, and excavation-induced ground movements often cause distortion and damage to adjacent buildings. Protection of adjacent structures occupies a major part of the cost, schedule and third-party impacts of urban development. To limit damage or mitigate their effects on nearby structures, it is highly important to understand the whole mechanism from excavation to building damage, and to estimate building damage reliably before excavation and provide appropriate measures. This paper investigates the effects of excavation-induced ground movements on nearby structures, considering soil-structure interactions for ground and structures, and a building damage criterion, which is based on the state of strain, is proposed. The criterion is compared with other existing damage estimation criteria and a procedure is finally provided for estimating building damage due to excavation-induced ground movements.

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Scenario-Based Earthquake Damage Estimation of Bridge Structures in Daegu City Using Hazus-MH Methodology (Hazus-MH 방법을 이용한 대구시 교량의 시나리오 지진에 의한 피해 예측)

  • Kim, Siyun;Kim, Sung Jig;Chang, Chunho
    • Journal of Korean Association for Spatial Structures
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    • v.18 no.4
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    • pp.89-96
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    • 2018
  • The paper presents the damage estimation of bridge structures in Daegu city based on the scenario-based earthquakes. Since the fragility curves for domestic bridge strucures are limited, the Hazus methodology is employed to derive the fragility curves and estimate the damage. A total of four earthuquake scenarios near Daegu city are assumed and structure damage is investigated for 81 bridge structures. The seismic fragility function and damage level of each bridge had adopted from the analytical method in HAZUS and then, the damage probability using seismic fragility function for each bridge was evaluated. It was concluded that the seismic damage to bridges was higher when the magnitude of the earthquake was large or nearer to the epicenter.

Development of the Wind Wave Damage Estimation Functions based on Annual Disaster Reports : Focused on the Western Coastal Zone (재해연보기반 풍랑피해예측함수 개발 : 서해연안지역)

  • Choo, Tai-Ho;Cho, Hyoun-Min;Shim, Sang-Bo;Park, Sang-Jin
    • The Journal of the Korea Contents Association
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    • v.18 no.1
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    • pp.154-163
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    • 2018
  • Not only South Korea but also Global world show that the frequency and damages of large-scale natural disaster due to the rise of heavy rain event and typhoon or hurricane intensity are increasing. Natural disasters such as typhoon, flood, heavy rain, strong wind, wind wave, tidal wave, tide, heavy snow, drought, earthquake, yellow dust and so on, are difficult to estimate the scale of damage and spot. Also, there are many difficulties to take action because natural disasters don't appear precursor phenomena However, if scale of damage can be estimated, damages would be mitigated through the initial damage action. In the present study, therefore, wind wave damage estimation functions for the western coastal zone are developed based on annual disaster reports which were published by the Ministry of Public Safety and Security. The wind wave damage estimation functions were distinguished by regional groups and facilities and NRMSE (Normalized Root Mean Square Error) was analyzed from 1.94% to 26.07%. The damage could be mitigated if scale of damage can be estimated through developed functions and the proper response is taken.

Structure damage estimation due to tunnel excavation based on indoor model test

  • Nam, Kyoungmin;Kim, Jungjoo;Kwak, Dongyoup;Rehman, Hafeezur;Yoo, Hankyu
    • Geomechanics and Engineering
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    • v.21 no.2
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    • pp.95-102
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    • 2020
  • Population concentration in urban areas has led traffic management a central issue. To mitigate traffic congestions, the government has planned to construct large-cross-section tunnels deep underground. This study focuses on estimating the damage caused to frame structures owing to tunnel excavation. When constructing a tunnel network deep underground, it is necessary to divide the main tunnel and connect the divergence tunnel to the ground surface. Ground settlement is caused by excavation of the adjacent divergence tunnel. Therefore, predicting ground settlement using diverse variables is necessary before performing damage estimation. We used the volume loss and cover-tunnel diameter ratio as the variables in this study. Applying the ground settlement values to the settlement induction device, we measured the extent of damage to frame structures due to displacement at specific points. The vertical and horizontal displacements that occur at these points were measured using preattached LVDT (Linear variable differential transformer), and the lateral strain and angular distortion were calculated using these displacements. The lateral strain and angular distortion are key parameters for structural damage estimation. A damage assessment chart comprises the "Negligible", "Very Slight Damage", "Slight Damage", "Moderate to Severe Damage", and "Severe to Very Severe Damage" categories was developed. This table was applied to steel frame and concrete frame structures for comparison.