• Title/Summary/Keyword: damage assessment

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Estimation of Fastened Condition of Bolts Using PZT Patches (압전소자를 이용한 볼트체결 상태계측 및 측정)

  • Chae, Kwan-Seok;Ha, Nam;Hong, Dong-Pyo;Chae, Hee-Chang
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.889-893
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    • 2004
  • This work presents a study on development of a practical and quantitative technique for assessment of the structural health condition by piezoelectric impedance-based technique associated with longitudinal wave propagation method. The bolt fastening condition is adjusted by torque wrench. In order to estimate the damage condition numerically, three damage indices, impedance peak frequency shift ${\Delta}F$ is proposed in this paper. Furthermore, an assessment method is described for estimation of the damage by using these three damage indices.

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Basic research for Health Monitoring Technique with PZT Patches (압전소자를 이용한 손상계측기술에 관한 기초연구)

  • Ha, Nam;Chae, Kwan-Suk;Hong, Dong-Pyo;Chae, Hee-Chang
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.870-874
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    • 2004
  • This work presents a study on development of a practical and quantitative technique for assessment of the structural health condition by Piezoelectric impedance-based technique associated with longitudinal wave propagation method. The bolt fastening condition is adjusted by torque wrench. In order to estimate the damage condition numerically, three damage indices, impedance peak frequency shift ${\Delta}F$, peak amplitude ratio $\delta$ and quality factor ratio $\gamma$, are proposed in this paper. Furthermore, an assessment method is described for estimation of the damage by using these three damage indices.

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Performance-based and damage assessment of SFRP retrofitted multi-storey timber buildings

  • Vahedian, Abbas;Mahini, Seyed Saeed;Glencross-Grant, Rex
    • Structural Monitoring and Maintenance
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    • v.2 no.3
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    • pp.269-282
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    • 2015
  • Civil structures should be designed with the lowest cost and longest lifetime possible and without service failure. The efficient and sustainable use of materials in building design and construction has always been at the forefront for civil engineers and environmentalists. Timber is one of the best contenders for these purposes particularly in terms of aesthetics; fire protection; strength-to-weight ratio; acoustic properties and seismic resistance. In recent years, timber has been used in commercial and taller buildings due to these significant advantages. It should be noted that, since the launch of the modern building standards and codes, a number of different structural systems have been developed to stabilise steel or concrete multistorey buildings, however, structural analysis of high-rise and multi-storey timber frame buildings subjected to lateral loads has not yet been fully understood. Additionally, timber degradation can occur as a result of biological decay of the elements and overloading that can result in structural damage. In such structures, the deficient members and joints require strengthening in order to satisfy new code requirements; determine acceptable level of safety; and avoid brittle failure following earthquake actions. This paper investigates performance assessment and damage assessment of older multi-storey timber buildings. One approach is to retrofit the beams in order to increase the ductility of the frame. Experimental studies indicate that Sprayed Fibre Reinforced Polymer (SFRP) repairing/retrofitting not only updates the integrity of the joint, but also increases its strength; stiffness; and ductility in such a way that the joint remains elastic. Non-linear finite element analysis ('pushover') is carried out to study the behaviour of the structure subjected to simulated gravity and lateral loads. A new global index is re-assessed for damage assessment of the plain and SFRP-retrofitted frames using capacity curves obtained from pushover analysis. This study shows that the proposed method is suitable for structural damage assessment of aged timber buildings. Also SFRP retrofitting can potentially improve the performance and load carrying capacity of the structure.

Analysis of Importance of Damaged Area Assessment Indices using Analytic Hierarchy Process (AHP 기법을 활용한 훼손지 평가항목의 중요도 분석)

  • Song, Ki-Hwan;Choi, Yun-Eui;Seok, Young-Sun;Jeon, Seong-Woo;Sung, Hyun-Chan;Seo, Jung-Young;Chon, Jin-Hyung
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.23 no.6
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    • pp.15-28
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    • 2020
  • Urbanization and industrialization have caused increasing damage to national lands, and ecological restoration has proceeded without any specific assessment of this damage. The purpose of this study is to select indices to assess damaged areas through literature review and panel discussions, and to derive the importance of damaged area assessment indices by analyzing them through the Analytic Hierarchy Process (AHP). This study has derived, via literature review, six types of damage and a total of 18 related assessment indices. A total of 51 responses were collected from surveys and given to experts, and an AHP analysis conducted. As a result of the analysis, "Landform change (0.268)" was of the highest importance, with associated damage types as follows: "Soil contamination (0.193)", "Vegetation damaged (0.149)", "Surface soil loss (0.143)", "Change in soil physiochemical property (0.125)", and "Vegetation decline (0.122)". The analysis determined that the item of the highest importance in the overall assessment of damage was "Slope occurred area (0.100)", and that "Conductivity (0.022)" was of the lowest importance. This study can be presented as a criterion in determining the type and degree of damage in setting priorities for future ecological restoration projects.

Model tests for the behavior assessment of adjacent buildings in urban tunnelling (터널굴착에 타른 인접건물의 거동평가에 대한 모형실험연구)

  • Hwang, Eui-Suk;Kim, Hak-Moon
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.9 no.3
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    • pp.251-261
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    • 2007
  • This study is to investigate the damage assessment of adjacent structures due to tunneling in urban environment. Model tests were carried out with two-story masonry building structures in various shapes and locations. The damage level of adjacent structures were very differently estimated in accordance with the shape ratio (L/h) of structures, construction stages, and various locations. The results of model tests were plotted on the damage level graphs in order to predict the direction of damage levels for the different types of structures (i.e. stiffness of structures, L/h). The progressive crack development mechanism at various construction stages was revealed through model tests and crack size indicated more conservative side of damage level on the damage level graph.

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Assessment of Vulnerable Area and Naval Ship's Vulnerability based on the Carleton Damage Function (칼튼 손상함수를 이용한 주요장비의 취약 면적 산정과 함정 취약성 평가 방법)

  • Lee, Jang Hyun;Choi, Won Jun
    • Journal of the Society of Naval Architects of Korea
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    • v.55 no.3
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    • pp.274-280
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    • 2018
  • This paper deals with the calculation of vulnerable areas of critical components required for the assessment of naval ship's vulnerability. Taking into account the effectiveness of threatening weapons, the probability density function of damage was used to assess vulnerable areas or vulnerabilities of critical components. It is shown that the vulnerable area of critical component can be simply computed from the damage function. Considering the weapon effectiveness of fragmentation and explosion on the target, both Carleton Damage Function and Rectangular Cookie Cutter Function representing the probability of damage are applied to the vulnerable area assessment. Carleton damage function is utilized to describe the weapon-target interaction in the vulnerability analyses. A problem of blast effect against an assumed naval ship is chosen as a case study. Vulnerability is evaluated by applying the suggested method to the equipments arranged in the engine room of the virtual ship.

Uncertainty analysis of containment dose rate for core damage assessment in nuclear power plants

  • Wu, Guohua;Tong, Jiejuan;Gao, Yan;Zhang, Liguo;Zhao, Yunfei
    • Nuclear Engineering and Technology
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    • v.50 no.5
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    • pp.673-682
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    • 2018
  • One of the most widely used methods to estimate core damage during a nuclear power plant accident is containment radiation measurement. The evolution of severe accidents is extremely complex, leading to uncertainty in the containment dose rate (CDR). Therefore, it is difficult to accurately determine core damage. This study proposes to conduct uncertainty analysis of CDR for core damage assessment. First, based on source term estimation, the Monte Carlo (MC) and point-kernel integration methods were used to estimate the probability density function of the CDR under different extents of core damage in accident scenarios with late containment failure. Second, the results were verified by comparing the results of both methods. The point-kernel integration method results were more dispersed than the MC results, and the MC method was used for both quantitative and qualitative analyses. Quantitative analysis indicated a linear relationship, rather than the expected proportional relationship, between the CDR and core damage fraction. The CDR distribution obeyed a logarithmic normal distribution in accidents with a small break in containment, but not in accidents with a large break in containment. A possible application of our analysis is a real-time core damage estimation program based on the CDR.

Damage Assessment Technique for Bridge Structures By Moving Load Tests and Optical Displacement Measurements (광변위 계측과 주행하중시험기법에 의한 교량구조의 손상도 추정기법)

  • Lee, Hyeong-Jin;Kim, Jong-Hoon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.1
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    • pp.769-777
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    • 2015
  • In this paper, a damage assessment technique using a moving load test and optical sensors was studied to overcome the deficiency of measurement information in bridge maintenance. Continuous displacements by applying the reciprocal theorem to the test can make the assessment simpler and more practical. Numerical and experimental studies were performed to show the efficiency and accuracy of the proposed technique as well as the possibility of a more realistic assessment for large infrastructure. The results showed that the assessed damage levels are quite accurate, and similar to the exact values in actual damage locations, even in the experiments. The proposed technique is useful and practical for both detecting damage locations and damage quantities.

Development of Integrated System for Safety Assessment of Damaged Ship (손상선박의 안전성 평가를 위한 통합시스템 개발)

  • Lee, Soon-Sup;Lee, Dong-Kon
    • Korean Journal of Computational Design and Engineering
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    • v.13 no.3
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    • pp.227-234
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    • 2008
  • The number of marine accidents have been decreased since various equipments for navigation control have been introduced to the marine vessels. However, disastrous marine accidents such as ship collisions are occurred more frequently. Therefore, IMO(International Maritime Organization) is enforcing the design requirement of structural strength for marine vessel. Also EU countries are developing new design methodologies and design tools to suggest the design guidance which can minimize the damage of commercial vessels in case of marine collision accidents. In this study, an integrated design system for the safety assessment has been presented to enhance the safety of damaged ships in marine collision accidents. The architecture of system is described by use-cases and IDEF functional analysis. Then an integrated system for safety assessment of damaged ship which is considering both damage stability and structural safety has been developed to support the ship design in early stage.

Fatigue Life Prediction of Weldment with Damage Mechanics (손상역학을 이용한 용접부의 피로수명예측)

  • Chung, Heung-Jin;Yoo, Byoung-Chan
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2008.04a
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    • pp.60-64
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    • 2008
  • According to previous research, welding-induced stress in steel structures can significantly affect the fatigue behaviour; it produces initial damage of weldiug part of structure locally and residual stresses reduce the fatigue strength after welding precess. In this study, through continuum damage mechanics, we can estimate the weldiug damage using the stress and strain history during welding process and the effect of welding residual stress for assessment of fatigue life. The variation of welding-induced stresses and strains need be traced precisely in advance for a reliable weldiug damage assessment. In this study, a damage and fatigue analysis techniques for steel structures with welding-induced residual stress are presented. First, We calculate the history of temperature according with welding process. And residual stress with a welding thermal history was evaluated by non-linear thermal stress analysis. Secondly, welding damage and fatigue life are estimated with kinetic damage law.

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