• Steel and Composite Structures
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• 제14권3호
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• pp.295-312
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• 2013

In this paper, a simplified approach based on critical temperature for fire resistance design of steel-concrete composite beams is proposed. The method for determining the critical temperature and fire protection of the composite beams is developed on the basis of load-bearing limit state method employed in current Chinese Technical Code for Fire safety of Steel Structure in Buildings. Parameters affecting the critical temperature of the composite beams are analysed. The results show that at a definite load level, section shape of steel beams, material properties, effective width of concrete slab and concrete property model have little influence on the critical temperature of composite beams. However, the fire duration and depth of concrete slab have significant influence on the critical temperature. The critical temperatures for commonly used composite beams, at various depth of concrete and fire duration, are given to provide a reference for engineers. The validity of the practical approach for predicting the critical temperature of the composite beams is conducted by comparing the prediction of a composite beam with the results from some fire design codes and full scale fire resistance tests on the composite beam.

• 대한조선학회논문집
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• 제57권2호
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• pp.70-79
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• 2020

The offshore installation units may be subjected to various accidental loads such as collision from supply vessels, impact from dropped objects, blast load from gas explosion and thermal load from fire. This paper deals with the design and strength evaluation method of the stiffened plate structures in response to a blast load caused by a gas explosion accident. It is a comprehensive review of various items used in actual project such as the size and type of the explosive loads, general design procedure/concept and analysis method. The structural analyses using simple analysis methods based on SDOF model and nonlinear finite element analysis are applied to the particular FPSO project. Also validation studies on the design guidance given by simple analysis method based on SDOF model have also considered several items such as backpressure effects, material behavior and duration time of the overpressure. A good correlation between the prediction made by simple analysis method based on SDOF model and nonlinear finite element analysis can be generally obtained up to the elastic limit.

• 한국지반공학회논문집
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• 제24권12호
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• pp.33-40
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• 2008

본 연구에서는 유한요소해석을 이용하여 암반에 근입된 현장타설말뚝의 말뚝-지반 상호작용즉, 지반의 연속성을 고려한 하중전이해석을 수행하였다. 이를 위하여 주면 하중전이함수를 사용자 정의의 경계면 모델(FRIC)로 구현하여 말뚝지반의 미끄러짐 거동과 하중전이 거동을 모델링 하였다. 본 연구결과, 주면마찰력에 의해 발생되는 선단침하량으로 대변되는 지반 연속성 영향은 주면마찰력이 극한상태로 도달할 때까지 증가함을 알 수 있었으며, 말뚝직경과 암반계수의 비(D/$E_{mass}$), 전체하중에서 주면마찰력의 비($R_s$/Q)에 영향을 받는 것으로 나타났다. 현장재하시험 사례와의 비교분석 결과, FRIC을 이용한 유한요소해석방법은 말뚝의 하중전이 거동과 말뚝-지반 상호작용 효과(coupling effect)를 적절히 나타낼 수 있었으며, 말뚝의 거동을 예측하는데 크게 개선되었음을 확인하였다.

• 대한기계학회논문집A
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• 제28권11호
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• pp.1741-1751
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• 2004

It is commonly requested that the steam generator tubes wall-thinned in excess of 40% should be plugged. However, the plugging criterion is known to be too conservative for some locations and types of defects and its application is limited to a single crack in spite of the fact that the occurrence of multiple through-wall cracks is more common in general. The objective of this research is to propose the optimum failure prediction models for two adjacent through-wall cracks in steam generator tubes. The conservatism of the present plugging criteria was reviewed using the existing failure prediction models for a single crack, and six new failure prediction models for multiple through-wall cracks have been introduced. Then, in order to determine the optimum ones among these new local or global failure prediction models, a series of plastic collapse tests and corresponding finite element analyses for two adjacent through-wall cracks in thin plate were carried out. Thereby, the reaction force model, plastic zone contact model and COD (Crack-Opening Displacement) base model were selected as the optimum ones for assessment of steam generator tubes with multiple through-wall cracks. The selected optimum failure prediction models, finally, were used to estimate the coalescence pressure of two adjacent through-wall cracks in steam generator tubes.

• 대한조선학회 특별논문집
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• 대한조선학회 2017년도 특별논문집
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• pp.32-37
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• 2017

Due to the nature of semi-submergible drilling rig, various equipments are arranged in a limited space, and therefore the many types of outfitting holes passing through the hull structure are densely arranged and that is required the detailed structural strength evaluation in terms of ULS and FLS by class or client. Particularly, semi-submergible drilling rig has a variety of global load which affects the structure strength around holes compared to general commercial ship, and its response of stress is also complicated, so it is difficult to carry out the prediction design of structural strength evaluation and reinforcement. In this regard, this paper presents a case study on the evaluation of structural strength for the various holes and large openings of semi-submergible drilling rig conducted by our company, as well as an established hole verification procedure.

• 대한기계학회논문집A
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• 제40권8호
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• pp.751-757
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• 2016

본 논문은 스테어케이스법을 사용하여 크랭크 스로 부품용 S34MnV강의 피로한도의 신뢰도를 평가하는 것이다. 크랭크 스로 부품의 소재는 S34MnV이며, 뜨임 및 풀림 열처리된 단조강이다. 본 연구에서는 설계피로강도의 신뢰도를 예측하기 위해 축 하중 일정진폭 피로시험을 수행하였다. 시험편은 평균응력 0 MPa의 동일한 응력부하를 적용하였고, 즉 응력비는 -1로 하였다. 피로시험 결과는 Dixon-Mood 접근법으로 평가하였다. 스테어케이스법에 의해 예측된 피로강도의 평균과 표준편차는 각각 296.3 MPa 및 10.6 MPa로 나타났다. 마지막으로 어떤 임의의 파손 확률에 대한 피로강도의 신뢰도를 예측하였다. 본 연구에서 제안한 예측법은 단조강의 설계 최적화를 위한 피로강도 값을 결정할 수 있다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1186-1191
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• 2003

The 40% of wall criterion, which is generally used for the plugging of steam generator tubes, may be applied only to a single crack. In the previous study, a total of 9 failure models were introduced to estimate the local failure of the ligament between cracks and the optimum coalescence model of multiple collinear cracks was determined among these models. It is, however, known that parallel axial cracks are more frequently detected during an in-service inspection than collinear axial cracks. The objective of this study is to determine the plastic collapse model which can be applied to the steam generator tube containing two parallel axial through-wall cracks. Nine previously proposed local failure models were selected as the candidates. Subsequently interaction effects between two adjacent cracks were evaluated to screen them. Plastic collapse tests for the plate with two parallel through-wall cracks and finite element analyses were performed for the determination of the optimum plastic collapse model. By comparing the test results with the prediction results obtained from the candidate models, a plastic zone contact model was selected as an optimum model.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.311-318
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• 2006

CFD simulation is a tool very useful to predict the generation and absorption of the contaminant from the construction materials for the single room condition. However, there is a limit in multi-room simulation for analyzing air movement and contaminant concentration at the condition that the door of each room was closed. A lot of network simulation tool were developed which can used to analyze the mass transfer and contaminant concentration as results in the multi-room condition. However, existing network simulation method was not able to analyze the change of the heating and cooling load with the ventilation as though the change of the indoor air-pollution density was predictable. In this study, new approach to predict heating/cooling load and indoor contaminant concentration will be reviewed. New indoor contaminant concentration module reviewed in this study wad coupled with existing ESP-r network simulation method. The validity of new approach will be analysed for comparison the results of simulation and field measurement results.

• Advances in concrete construction
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• 제16권4호
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• pp.217-230
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• 2023

Methods for designing the post-tensioned anchorage zones at ultimate limit state has been specified in current design codes based on strut-and-tie models (STM). However, it is still not clear how to estimate the serviceability behavior of the anchorage zones. The serviceability is just indirectly taken into account by means of the reasonable reinforcement detailing. To address this issue, this paper is devoted to developing a modified strut-and-tie model (MSTM) to predict the behavior of concentric anchorage zones throughout the loading process. The principle of stationary complementary energy is introduced into STM at each load step to satisfy the compatibility condition and generate the unique MSTM. The structural behavior of anchorage zones can be achieved based on MSTM from loading to failure. Simplified formulas have been proposed to estimate the first cracking load, bearing capacity and maximum crack width with the consideration of the details of reinforcement bursting bars. The proposed model provides a definite method to control the bursting crack width in concentric anchorage zones. Four specimens with different bearing plate ratios have been designed and tested to validate the proposed method.

• 한국정밀공학회지
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• 제21권1호
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• pp.173-180
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• 2004

This paper presents the effect of varying boundary conditions such as ground subsidence, internal pressure and temperature variation for buried pipelines on failure prediction by using a failure probability model. The first order Taylor series expansion of the limit state function incorporating with von-Mises failure criteria is used in order to estimate the probability of failure mainly associated with three cases of ground subsidence. Using stresses on the buried pipelines, we estimate the probability of pipelines with von-Mises failure criterion. The effects of varying random variables such as pipe diameter, internal pressure, temperature, settlement width, load for unit length of pipelines, material yield stress and pipe thickness on the failure probability of the buried pipelines are systematically studied by using a failure probability model for the pipeline crossing ground subsidence regions which have different soil properties.