• 제목/요약/키워드: Calculation of Damages

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Longitudinal Strength Safety and Refloat Calculation of a Grounded Ship (좌초 선박의 종강도 안전성 및 부양계산 기술 개발)

  • 강창구;김진환
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.4 no.2
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    • pp.35-42
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    • 1998
  • Marine casuality causes not only loss of lives and ships, but also severs damages to marine environment and related economic activities such as fishing industry, sea farming, and tourist industry. Basically, the great effort should be made to prevent the occurrence of maritime accidents by any means. However, once accident has occurred, the salvage works should be done rapidly and properly based on theoretical and technical informations, which could minimize the risk during salvage operation and the overall damage from the maritime accidents. Generally, to calculate accurate hydrostatics of a stranded ship, a large amount of input data is needed. But, an availability and a reliability of input data cannot be guaranteed in most situations, and the adequate time required for preparing all input data is not allowed to perform the timely operations of salvage. In this paper, the development process of simple computer program for salvage operation using limited input data is introduced and its application example is presented. This program was developed to provide technical support for planning salvage operations in the grounding accident.

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Diffusion study for chloride ions and water molecules in C-S-H gel in nano-scale using molecular dynamics: Case study of tobermorite

  • Zehtab, Behnam;Tarighat, Amir
    • Advances in concrete construction
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    • v.4 no.4
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    • pp.305-317
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    • 2016
  • Porous materials such as concrete could be subjected to aggressive ions transport. Durability of cement paste is extremely depended on water and ions penetration into its interior sections. These ions transport could lead different damages depending on reactivity of ions, their concentrations and diffusion coefficients. In this paper, chloride diffusion process in cement hydrates is simulated at atomistic scale using molecular dynamics. Most important phase of cement hydrates is calcium silicate hydrate (C-S-H). Tobermorite, one of the most famous crystal analogues of C-S-H, is used as substrate in the simulation model. To conduct simulation, a nanopore is considered in the middle of simulation cell to place water molecules and aggressive ions. Different chloride salts are considered in models to find out which one is better for calculation of the transport properties. Diffusion coefficients of water molecules and chloride ions are calculated and validated with existing analytical and experimental works. There are relatively good agreements among simulation outputs and experimental results.

A Study of Dynamic Characteristic of the Leaf Spring for Freight Wagon After the Derailment (탈선 후 화물열차의 겹판스프링 동적특성 연구)

  • 이응신;이장무
    • Journal of the Korean Society for Railway
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    • v.7 no.1
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    • pp.49-54
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    • 2004
  • Particularly derailing freight wagon, which are loaded with dangerous chemicals, has large damages on humans and environment. In this paper the dynamic characteristic of the laminated leaf spring under extreme situation, for example derailment, is examined. The leaf spring has a static hysteresis. Not only the friction value, but also the spring rate are influenced by this hysteresis characteristic. Because of the static hysteresis of the leaf spring the spring rate must be used in normal operation depending upon the loading and the kind of the excitation with the up to 10-fold value of the static spring rate. Some characteristics of the leaf spring can be treated like well-known viscous damping, but fer special situation (preload and/or excitation) particular calculation are necessary.

Optimal Flood Control System for Irrigation Reservoir (관개저수지의 최적 홍수관리방안)

  • 문종필;민진우;김영식;박승기;김태철
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 1998.10a
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    • pp.311-317
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    • 1998
  • Recently irrigation reservoir has been developed to perform multipurpose function. To get a maximum effect it requires to establish optimal management system for irrigation reservoir in drought and flood season. Especially we dealt with optimal flood control system for irrigation reservoir in this study. This system consists of real-time rainfall data via online system, real-time flood forecasted by SCS method in hourly basis, storage volume by water balance equation, optimal releasing discharge from the gate, the water level in right downstream, and calculation of innundated area, depth, and time using GIS, and amount of flood damages. If we consider the relation of these sub module reasonably, we can reach the optimal flood control to minimize flood damage

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Estimation of elastic and plastic zones near a tunnel considering in situ rock mass conditions and the damage induced by excavation (원지반의 암반조건과 시공으로 인한 손상을 고려한 터널주변 탄·소성영역의 산정)

  • Sagong, Myung;Paik, Kyuho
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.6 no.3
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    • pp.227-235
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    • 2004
  • Tunneling in rock mass produces two types of damages in the vicinity of a tunnel: structural and constructional damages. Structural damage represents the damage induced by the unbalance of geostatic stress caused by the tunneling, and constructional damage is the damage produced during the construction. In this study, formulations of tangential and radial stresses in the elastic and plastic zones near a tunnel, and the calculation of radius of plastic zone surrounding a tunnel are introduced by modifying the Hoek-Brown criterion of 2002 edition, which has capability of considering in situ rock mass characteristics and construction damage. From the parametric study, influences of rock mass quality, uniaxial compressive strength of intact rock, and the dimension of the tunnel on the plastic zone are investigated. The accuracy of the proposed approach is evaluated by comparing with results from the previous study.

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Prediction of force reduction factor (R) of prefabricated industrial buildings using neural networks

  • Arslan, M. Hakan;Ceylan, Murat;Kaltakci, Yaspr M.;Ozbay, Yuksel;Gulay, Fatma Gulten
    • Structural Engineering and Mechanics
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    • v.27 no.2
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    • pp.117-134
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    • 2007
  • The force (load) reduction factor, R, which is one of the most important parameters in earthquake load calculation, is independent of the dimensions of the structure but is defined on the basis of the load bearing system of the structure as defined in earthquake codes. Significant damages and failures were experienced on prefabricated reinforced concrete structures during the last three major earthquakes in Turkey (Adana 1998, Kocaeli 1999, Duzce 1999) and the experts are still discussing the main reasons of those failures. Most of them agreed that they resulted mainly from the earthquake force reduction factor, R that is incorrectly selected during design processes, in addition to all other detailing errors. Thus this wide spread damages caused by the earthquake to prefabricated structures aroused suspicion about the correctness of the R coefficient recommended in the current Turkish Earthquake Codes (TEC - 98). In this study, an attempt was made for an approximate determination of R coefficient for widely utilized prefabricated structure types (single-floor single-span) with variable dimensions. According to the selecting variable dimensions, 140 sample frames were computed using pushover analysis. The force reduction factor R was calculated by load-displacement curves obtained pushover analysis for each frame. Then, formulated artificial neural network method was trained by using 107 of the 140 sample frames. For the training various algorithms were used. The method was applied and used for the prediction of the R rest 33 frames with about 92% accuracy. The paper also aims at proposing the authorities to change the R coefficient values predicted in TEC - 98 for prefabricated concrete structures.

A Case Study on Installation Charges Dispute Settlement by Benefits Analysis (시설부담금 산정에 관한 분쟁 사례 연구)

  • Lee, Tai-Sik;Lee, Dong-Wook;Jun, Young-Joon;Kwak, Dong-Koo
    • Journal of Arbitration Studies
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    • v.20 no.1
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    • pp.169-189
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    • 2010
  • Composition depending on the development of industrial sites are located just within the existing facilities are hoping to become a retention, in accordance with the law will impose a liability amount. Then calculating the profit and loss analysis of the retention is required. In other words, the composition of the industrial site will be retained for existing facilities and the amount of the profit is necessary to analyze. In this study, the calculation of expenses and the income of retained existing facilities will be presented with analytical methods. Especially the existing cases of dispute with the results of the adjustment and the calculation of contributions for a range of benefits associated with the analysis according to 'The Industrial Sites and Development Act', the following conclusions were drawn. According to 'The Industrial Sites and Development Act', the facility at the industrial site composition within the limits of increasing the convenience of being charged is reasonable. In particular, the industrial site of buildings located within existing facilities depending on the composition and future industrial sites are public facilities available for the facility to consider the possibility of calculating contributions to be reasonable. Additional benefits which can be the land prices, tax exemptions, and increasing efficiency of land use for the benefits are not yet realized the benefits against the expenses side, as well as imposing double taxation. Therefore, the heavy emphasis on convenience is not considered to be reasonable. Including in the industrial site, the cost of damages caused, that is, noise, pollution, and the defective product possibility should be considered a side opinion, but it still does not promote the development of states estimated the cost of the damage is not right to be counted. Therefore, this facility should not be included in calculating contributions.

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Collapse response assessment of low-rise buildings with irregularities in plan

  • Manie, Salar;Moghadam, Abdoreza S.;Ghafory-Ashtiany, Mohsen
    • Earthquakes and Structures
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    • v.9 no.1
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    • pp.49-71
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    • 2015
  • The present paper aims at evaluating damage and collapse behavior of low-rise buildings with unidirectional mass irregularities in plan (torsional buildings). In previous earthquake events, such buildings have been exposed to extensive damages and even total collapse in some cases. To investigate the performance and collapse behavior of such buildings from probabilistic points of view, three-dimensional three and six-story reinforced concrete models with unidirectional mass eccentricities ranging from 0% to 30% and designed with modern seismic design code provisions specific to intermediate ductility class were subjected to nonlinear static as well as extensive nonlinear incremental dynamic analysis (IDA) under a set of far-field real ground motions containing 21 two-component records. Performance of each model was then examined by means of calculating conventional seismic design parameters including the response reduction (R), structural overstrength (${\Omega}$) and structural ductility (${\mu}$) factors, calculation of probability distribution of maximum inter-story drift responses in two orthogonal directions and calculation collapse margin ratio (CMR) as an indicator of performance. Results demonstrate that substantial differences exist between the behavior of regular and irregular buildings in terms of lateral load capacity and collapse margin ratio. Also, results indicate that current seismic design parameters could be non-conservative for buildings with high levels of plan eccentricity and such structures do not meet the target "life safety" performance level based on safety margin against collapse. The adverse effects of plan irregularity on collapse safety of structures are more pronounced as the number of stories increases.

Calculating Expected Damage of Breakwater Using Artificial Neural Network for Wave Height Calculation (파고계산 인공신경망을 이용한 방파제 기대피해도 산정)

  • Kim, Dong-Hyawn;Kim, Young-Jin;Hur, Dong-Soo;Jeon, Ho-Sung;Lee, Chang-Hoon
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.22 no.2
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    • pp.126-132
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    • 2010
  • An approach to calculating expected damage of breakwater assisted by artificial neural network was developed. Wave height in front of a breakwater was predicted by a trained artificial neural network with inputs of wave height in deep ocean and tidal level. Prediction results by the neural network can be comparable to that by professional numerical model for wave transformation. Using the wave prediction neural network, it was very easy and fast to obtain a number of significant waves at breakwater and finally analysis time for expected damage can be shortened. In addition, the effect of considering tidal level in the calculation of expected damage was revealed by comparing the expected damages with and without tidal variation. Therefore, it was pointed out that tidal variation should be considered to improve prediction accuracy.

Fracture behaviors of tunnel lining caused by multi-factors: A case study

  • Zhao, Yiding;Zhang, Yongxing;Yang, Junsheng
    • Advances in concrete construction
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    • v.8 no.4
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    • pp.269-276
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    • 2019
  • The cracking and spalling caused by fracture of concrete lining have adverse impacts on serviceability and durability of the tunnel, and the subsequent maintenance work for damaged structure needs to be specific to the damaging causes. In this paper, a particular case study of an operational tunnel structure is presented for the serious cracking and spalling behaviours of concrete lining, focusing on the multi-factors inducing lining failure. An integrated field investigation is implemented to characterize the spatial distribution of damages and detailed site situations. According to results of nondestructive inspection, insufficient lining thickness and cavity behind lining are the coupled-inducement of lining failure bahaviors. To further understanding of the lining structure performance influenced by these multiple construction deficiencies, a reliable numerical simulation based on extended finite element method (XFEM) is performed by using the finite element software. The numerical model with 112 m longitudinal calculation, 100 m vertical calculation and 43 m vertical depth, and the concrete lining with 1450 solid elements are set enrichment shape function for the aim of simulating cracking behavior. The numerical simulation responses are essentially in accordance with the actual lining damaging forms, especially including a complete evolutionary process of lining spalling. This work demonstrates that the serious lining damaging behaviors are directly caused by a combination of insufficient thickness lining and cavity around the surrounding rocks. Ultimately, specific maintenance work is design based on the construction deficiencies, and that is confirmed as an efficient, time-saving and safe maintenance method in the operational railway tunnel.