• Title/Summary/Keyword: structural evaluation

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Consideration for a Proper Stress Definition in Fatigue Analysis of Welded Structures

  • Kim, Myung-Hyun;Kang, Sung-Won
    • Proceedings of the KWS Conference
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    • 2005.06a
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    • pp.396-398
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    • 2005
  • At present, fatigue design of welded structures is primarily based on nominal stress or hot spot stress approach with a series of classified weld S-N curves. However, these methods are known to possess drawbacks, such as difficulty associated with defining proper nominal stress and the finite element sue sensitivity etc. Recently, a mesh-size insensitive structural stress definition is proposed by Battelle that gives a stress state at weld toe with relatively large mesh size. The structural stress definition is based on the elementary structural mechanics theory and provides an effective measure of a stress state in front of weld toe. As an experimental validation of the structural stress method in obtaining the fatigue strength of weldments, a series of experiment is carried out for various sizes of weldments. Based on the result from this study, it is expected to develop a more precise fatigue strength evaluation technique and to save time period required in the fatigue design of ship and offshore structures.

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Structural Test and Safety Evaluation for Fin Assembly of Scientific Sound Rocket (과학로케트 날개조립체의 구조강도시험 및 안전성 평가)

  • 허용학;김갑순;주진원
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.12
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    • pp.3395-3403
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    • 1994
  • The structural test technique and equipment for strength test of astronautical structures, such as rocket, were presented in this paper. Structural strength tests of the fin assembly with fin and fin frame in the scientific sound rocket were performed with load levels of 100% limit load and 150% ultimate load of design lift force. Safety factors in each part of the fin assembly were calculated at these two load levels and the stiffnesses based on the measured deflection of fin assembly and strains on fin and fin frame were evaluated at these two load level. As the result of structural test, the fin assembly was estimated to be safe.

Elastic High-temperature Structural Analysis on the Small Scale PHE Prototype Considering the Pipeline Stiffness (배관 강성을 고려한 소형 공정열교환기 시제품에 대한 탄성 고온구조해석)

  • Song, Kee-nam;Kang, J-H;Hong, S-D;Park, H-Y
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.7 no.3
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    • pp.48-53
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    • 2011
  • A PHE (Process Heat Exchanger) is a key component required to transfer heat energy of $950^{\circ}C$ generated in a VHTR (Very High Temperature Reactor) to the chemical reaction that yields a large quantity of hydrogen. A small-scale PHE prototype made of Hastelloy-X is being tested in a small-scale gas loop at Korea Atomic Energy Research Institute. In this study, as a part of the evaluation on the high-temperature structural integrity of the small-scale PHE prototype, we carried out macroscopic high-temperature structural analysis of the small-scale PHE prototype under the gas loop test conditions considering the pipeline stiffness.

Experimental analysis of a semi-actively controlled steel building

  • Occhiuzzi, Antonio;Spizzuoco, Mariacristina
    • Structural Engineering and Mechanics
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    • v.19 no.6
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    • pp.721-747
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    • 2005
  • The strong need of verifying theories formulated for semi-active control through applications to real structures is due to the fact that theoretical research on semi-active control systems is not matched by a corresponding satisfactory experimental activity. This paper shows how a smart system including magnetorheological devices as damping elements can be implemented in a large-scale structural model, by describing in detail the kind of electronics (dedicated hardware and software) adopted during the experimental campaign. It also describes the most interesting results in terms of reduction of the seismic response (either experimental or numerical) of the semi-actively controlled structure compared to a passive operating control system, and in terms of the evaluation criteria proposed in the benchmark for seismically excited controlled buildings. The paper also explains how to derive from the classical theory of optimal control the adopted control logic, based on a clear physical approach, and provides an exhaustive picture of the time delays characterizing the control sequence.

Fatigue performance assessment of welded joints using the infrared thermography

  • Fan, J.L.;Guo, X.L.;Wu, C.W.
    • Structural Engineering and Mechanics
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    • v.44 no.4
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    • pp.417-429
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    • 2012
  • Taking the superficial temperature increment as the major fatigue damage indicator, the infrared thermography was used to predict fatigue parameters (fatigue strength and S-N curve) of welded joints subjected to fatigue loading with a high mean stress, showing good predictions. The fatigue damage status, related to safety evaluation, was tightly correlated with the temperature field evolution of the hot-spot zone on the specimen surface. An energetic damage model, based on the energy accumulation, was developed to evaluate the residual fatigue life of the welded specimens undergoing cyclic loading, and a good agreement was presented. It is concluded that the infrared thermography can not only well predict the fatigue behavior of welded joints, but also can play an important role in health detection of structures subjected to mechanical loading.

Effect of brick infill panel on the seismic safety of reinforced concrete frames under progressive collapse

  • Tavakoli, Hamidreza;Akbarpoor, Soodeh
    • Computers and Concrete
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    • v.13 no.6
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    • pp.749-764
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    • 2014
  • Structural safety has always been a key preoccupation for engineers responsible for the design of civil engineering projects. One of the mechanisms of structural failure, which has gathered increasing attention over the past few decades, is referred to as 'progressive collapse' which happens when one or several structural members suddenly fail, whatever the cause (accident, attack, seismic loading(.Any weakness in design or construction of structural elements can induce the progressive collapse in structures, during seismic loading. Masonry infill panels have significant influence on structure response against the lateral load. Therefore in this paper, seismic performance and shear strength of R.C frames with brick infill panel under various lateral loading patterns are investigated. This evaluation is performed by nonlinear static analysis. The results provided important information for additional design guidance on seismic safety of RC frames with brick infill panel under progressive collapse.

Structural Damage Evaluation of Large Span Roof Structure using Artificial Neural Network (인공신경망을 이용한 대공간구조물 구조손상평가)

  • Cho, Ja-Ock;Kim, Ji-Young;Yu, Eun-Jong;Kim, Mi-Jin;Kim, Dae-Young
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2010.04a
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    • pp.335-338
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    • 2010
  • 구조물의 상태평가는 구조물 고유의 동특성을 분석함으로써 평가할 수 있다. 구조물은 태풍, 지진 및 기타 외적 환경 등에 의하여 손상이 발생하고 이러한 구조물의 손상은 강성의 변화로 이어져 구조물의 동특성에 변화를 일으킨다. 따라서 손상 발생 전후의 동적응답을 각각 계측한 후 구조물 식별(Structural System Idetification)을 통하여 고유진동수 및 모드형상을 추출하고 수학적인 기법을 사용하여 구조물을 구성하고 있는 개별 부재 혹은 부재 그룹의 강성을 비교함으로써 손상의 발생여부 및 손상정도를 추정할 수 있다. 본 연구에서는 지붕트러스 구조물에 대하여 손상평가를 수행하고 이를 검증할 수 있는 Mock-up 구조물을 설계 및 시공하였다.

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A Study on the Relationship between Sound Quality and Structural Mechanics in Automobiles (차량 구조 강성과 소음 음질간의 상관도 연구)

  • Choi Jongdae;Kim Sangmin
    • Proceedings of the Acoustical Society of Korea Conference
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    • autumn
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    • pp.239-242
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    • 2000
  • In the present study, the influence of car body structures to the noise and vibration characteristics has been sought. The numerical modal analysis for the body-in-white is employed to predict the vibratory response of structure, and then followed by the experimental modal testing to confirm the validity of the model. Using the results of numerical simulations with the designated modal parameters, the optimal structural configuration has been deduced. Special interests have been paid to the sensitivity of sound quality to the structural integrity. Since the structural integrity has a close relationship to the structure-born noise, the substantially low frequency range, which is far below the frequency range almost barely sensible by human auditory organ but still quite influential to overall impression, is especially examined. The subjective assessment agrees with the objective evaluation by means of traditional sound measures as well as psychoacoustic metrics.

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Bridge Safety Evaluation Based on the System Identification (구조동정법(構造同定法)에 의한 교량(橋梁)의 안전성(安全性) 평가(評價))

  • Kim, Kee-Dae;Lee, Sang-Wha
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.2 no.2
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    • pp.162-169
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    • 1998
  • This paper presents the application of system identification approaches for the safety assessment of RC-T type bridge based on the result of field test. For these problems, the moment of inertia of cross-sectional area and the natural frequency of bridge were used as structural parameters, the SAP90 program for the structural analysis and the SLP method for the minimum error. As a result, it is found that the proposed algorithm for this study appears applicable to real structures with reasonable complexity. It is shown that the introduction of approximate quadratic equations is more realistic and timesaving than the common methods.

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Recent Advances in Structural Health Monitoring

  • Feng, Maria Q.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.27 no.6
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    • pp.483-500
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    • 2007
  • Emerging sensor-based structural health monitoring (SHM) technology can play an important role in inspecting and securing the safety of aging civil infrastructure, a worldwide problem. However, implementation of SHM in civil infrastructure faces a significant challenge due to the lack of suitable sensors and reliable methods for interpreting sensor data. This paper reviews recent efforts and advances made in addressing this challenge, with example sensor hardware and software developed in the author's research center. It is proposed to integrate real-time continuous monitoring using on structure sensors for global structural integrity evaluation with targeted NDE inspection for local damage assessment.