• 한국항해항만학회지
• /
• 제41권3호
• /
• pp.165-172
• /
• 2017

현행 해양유출사고 시나리오는 예상가능한 최대 유출사고를 근거로 하여 시나리오가 작성되었다. 하지만, 최대유출사고 시나리오와 유사한 규모의 사고는 실제 거의 일어나지 않았는데, 이러한 시나리오를 바탕으로 한 훈련이나 대응장비배치 등은 대비 측면에서 본다면 낮은 비용효율을 가지는 것으로 볼 수 있다. 현행의 시나리오는 활용성과 현장도가 높은 시나리오 구현을 통한 실전에 가까운 형태로 구성될 필요가 있고, 활용 목적에 적합하도록 설계될 필요가 있다. 따라서, 본 연구에서는 과거 사고사례를 바탕으로 한 시나리오 작성을 위해 기 개발된 HNS 사고 표준코드를 활용하여 현행 시나리오를 대체할 수 있는 대체 사고 시나리오(Alternative Accident Scenario)를 구성하고자 하였다. 시나리오는 HNS 사고 표준코드를 모듈화하여 최대 빈도 시나리오, 최대 피해 시나리오, 최대 취약성 시나리오 3가지로 구분하여 작성하였다. 이런 과정을 거쳐 제시된 각 시나리오별로 제시된 사고발생 상황은 실제 사고와 유사한 형태를 나타내므로 현장에서의 합목적적인 활용이 가능할 것으로 판단된다.

• Smart Structures and Systems
• /
• 제3권4호
• /
• pp.475-494
• /
• 2007

This paper deals with the development of an innovative distributed construction system based on smart prefabricated concrete elements for the real-time condition assessment of civil infrastructure. So far, two reduced-scale prototypes have been produced, each consisting of a $0.2{\times}0.3{\times}5.6$ m RC beam specifically designed for permanent instrumentation with 8 long-gauge Fiber Optic Sensors (FOS) at the lower edge. The sensing system is Fiber Bragg Grating (FBG)-based and can measure finite displacements both static and dynamic with a sample frequency of 625 Hz per channel. The performance of the system underwent validation in the laboratory. The scope of the experiment was to correlate changes in the dynamic response of the beams with different damage scenarios, using a direct modal strain approach. Each specimen was dynamically characterized in the undamaged state and in various damage conditions, simulating different cracking levels and recurrent deterioration scenarios, including cover spalling and corrosion of the reinforcement. The location and the extent of damage are evaluated by calculating damage indices which take account of changes in frequency and in strain-mode-shapes. The outcomes of the experiment demonstrate how the damage distribution detected by the system is fully compatible with the damage extent appraised by inspection.

• Structural Engineering and Mechanics
• /
• 제48권2호
• /
• pp.257-274
• /
• 2013

In this study, seismic performance of one story hinged precast buildings, which represents the majority of existing lightweight industrial building stock of Turkey, was assessed. A lot of precast buildings, constructed in one of the important seismic zones of western Turkey, were investigated and building inventories were prepared. By this method, structural properties of inventory buildings and damaged precast buildings in recent earthquakes were compared. Damage estimations based on nonlinear analysis methods have shown that estimated damage levels of inventory buildings and observed damage levels in recent earthquakes are similar. Accuracy of damage estimation study and the simplicity of the one story precast building models implied that rapid seismic performance assessment method for these buildings can be developed. In this assessment method, capacity curves and vibration periods of precast buildings were calculated by using structural properties of precast buildings. The proposed assessment method was applied to inventory buildings by using two different seismic demand scenarios which reflect moderate and soft soil conditions. Comparison of detailed analysis and rapid assessment methods have indicated that reliable seismic performance estimations can be performed by using proposed method. It is also observed that distribution of damage estimations is compatible in both scenarios.

• 대한조선학회논문집
• /
• 제59권6호
• /
• pp.413-422
• /
• 2022

Blast Hardened Bulkheads (BHB) are used to suppress damage propagation by internal explosions to reduce ships'vulnerability. However, for this reason, the weight of the ship inevitably increased, and other functions such as the ships'mobility were bound to deteriorate. Therefore, it is essential in the initial design of the ship to optimize the dimensions of the bulkhead to minimize the weight while decreasing the vulnerability of the ship. Research on design optimization of BHB has been conducted, but it has not considered explosive load in various hit scenarios. This study proposed an optimal design method for the curtain plate type blast hardened bulkhead, which is currently frequently applied by the Korean Navy in consideration of various hit scenarios. Using genetic algorithms, multiobjective design optimizations that minimize weight increase as well as minimize damage to ships were obtained. By optimizing the dimensions of the BHB considering various hit scenarios, the ship's vulnerability was improved while maintaining its mobility due to weight reduction.

• 한국건설관리학회논문집
• /
• 제18권2호
• /
• pp.81-90
• /
• 2017

임진강 유역은 1996년부터 1999년까지 3번의 대규모 홍수가 발생하여 많은 인명피해와 9천억원의 재산피해를 입었다. 우리나라는 기후변화로 인하여 홍수피해가 앞으로 증가할 것으로 예상된다. 본 연구는 기후시나리오를 활용하여 미래의 홍수피해를 예측하고, 실물옵션 기반 경제성분석 방법을 제시하였으며, 임진강유역의 홍수방지시설물 투자사업의 사례연구를 통해 경제성분석을 실시하였다. RCP (Representative Concentration Pathway) 기후시나리오에서 모의된 강수량 자료를 활용하여 홍수피해액을 계산하고, 홍수방지시설물 투자에 의한 저감이익을 분석하였다. 향후 RCP8.5와 RCP4.5 기후시나리오가 실현되는 조건을 가정하여 홍수피해 저감이익의 변동성을 구하고, 2071년에 200년 재현주기에 적응하도록 하는 확장을 위한 투자를 할 수 있는 확장옵션을 적용하여 프로젝트의 옵션가치를 구했다. 옵션가치 분석결과, 두 가지 시나리오 하에서 경제성을 확보하고 있음을 확인하였고, RCP8.5 기후시나리오가 실현될 때가 RCP4.5의 경우보다 홍수피해 저감이익이 더 많이 발생하였다. 본 연구는 정부 의사결정권자가 실물옵션분석방법을 활용하여 홍수방재시설물의 경제성분석에 기후변화 불확실성을 고려할 수 있도록 도와줄 것으로 기대되며, 기후시나리오에서 제공하는 강우자료를 활용하여 기후위험요소를 경제적 가치로 정량화하는 방법을 제시하였다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2006년도 춘계 학술발표회 논문집
• /
• pp.960-969
• /
• 2006

In this study, a series of fire tests was carried out to evaluate fire-induced damage to structural members in tunnels. From the tests, the loss amount of concrete materials by the RWS fire scenario was slightly bigger than by the RABT fire scenario. Especially under the RWS fire scenario where the maximum temperature is over 1,200, the loss of concrete materials was mainly induced by melting. Generally, the loss of materials in reinforced concrete was slightly smaller than that in unreinforced concrete. Depending upon an applied fire scenario, fire-induced damage to shotcrete was quite different. From the real-time investigation of a specimen surface by a digital camcorder, it was proved that the material loss under the RABT fire scenario was mainly induced by spalling. However, it was also revealed that although fire-induced damage in the initial heating stage under the RWS was so close to that under the RABT, the material loss under the RWS at the later stage after 50 minutes elapsed since fire initiation was induced not by spalling but by melting.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2004년도 봄 학술발표회 논문집
• /
• pp.41-47
• /
• 2004

The objective of this paper is to monitor damage in beam-type structures by using time history of natural frequencies. First, numerical experiments on test beams are described, Dynamic responses of the test structures are obtained for several damage scenarios in a consequent order. Next, the time history of natural frequencies are extracted for the first four modes from the dynamic responses of the test structures. Finally, damage detection in the test structures is performed using the time-history of natural frequencies.

• Smart Structures and Systems
• /
• 제18권5호
• /
• pp.983-1004
• /
• 2016

Nowadays, there are two classes of methods for damage detection in structures consisting of static and dynamic. The dynamic methods are based on studying the changes in structure's dynamic characteristics. The theoretical basis of this method is that damage causes changes in dynamic characteristics of structures. The dynamic methods are divided into two categories: signal based and modal based. The modal based methods utilize the modal properties consisting of natural frequencies, modal damping and mode shapes. As the modal properties are sensitive to changes in the structure, these can be used for detecting the damages. In this study, using dynamic method and modal based approach (natural frequencies and mode shapes), the objective function is formulated. Then, detection of damages of truss structures is addressed by using Simplified Dolphin Echolocation algorithm and solving inverse optimization problem. Many scenarios are used to simulate the damages. To demonstrate the ability of the algorithm, different truss structures with several multiple elements scenarios are tested using a few runs. The influence of the two different levels of noise in the modal data for these scenarios is also considered. The last example of this article is investigated using a different mutation. This mutation obtains the exact answer with fewer loops and population by limited computational effort.

• Architectural research
• /
• 제13권4호
• /
• pp.53-60
• /
• 2011

Damage detection algorithms based on a one-dimensional beam model can detect damage within a beam span caused by flexure only but cannot detect damage at a joint with prescribed boundary conditions or at the middle part of a beam section where the neutral axis is located. Considering the damage at a welded joint of beam elements in steel structures and modeling the damage with twodimensional plane elements, this study presents a new approach to detecting damage in the depth direction of the joint and beam section. Three damage scenarios at the upper, middle, and lower parts of a welded joint of a rectangular symmetric section are investigated. The damage is detected by evaluating the difference in the receptance magnitude between the undamaged and damaged states. This study also investigates the effect of measurement locations and noise on the capability of the method in detecting damage. The numerical results show the validity of the proposed method in detecting damage at the beam's welded joint.

• Structural Engineering and Mechanics
• /
• 제67권4호
• /
• pp.327-336
• /
• 2018

In this study, an efficient damage index is proposed to identify multiple damage cases in structural systems using the concepts of frequency response function (FRF) matrix and strain energy of a structure. The index is defined based on the change of strain energy of an element due to damage. For obtaining the strain energy stored in elements, the columnar coefficients of the FRF matrix is used. The new indicator is named here as frequency response function strain energy based index (FRFSEBI). In order to assess the performance of the proposed index for structural damage detection, some benchmark structures having a number of damage scenarios are considered. Numerical results demonstrate that the proposed index even with considering noise can accurately identify the actual location and approximate severity of the damage. In order to demonstrate the high efficiency of the proposed damage index, its performance is also compared with that of the flexibility strain energy based index (FSEBI) provided in the literature.