• Title/Summary/Keyword: 선박거동

Search Result 239, Processing Time 0.024 seconds

Centrifugal Test on Behavior of the Dolphin Structure under Ship Collision (선박충돌 시 돌핀 구조물의 거동에 대한 원심모형실험)

  • Oh, SeungTak;Bae, WooSeok;Cho, SungMin;Heo, Yol
    • Journal of the Korean GEO-environmental Society
    • /
    • v.12 no.1
    • /
    • pp.61-70
    • /
    • 2011
  • The impact protection system consists of an arrangement of circular sheet pile cofferdams-denoted dolphin structuredeeply embedded in the seabed, filled with crushed rock and closed at the top with a robust concrete cap. Centrifuge model tests were performed to investigation the behaviors of dolphins in this study. Total 7 quasi-model tests and 11 dynamic model tests were performed. The main experimental results can be summarized as follows. Firstly, The experimental force-displacement results for quasi-static tests show a limited influence on the initial stiffness of the structure from the change in fill density and the related change in the stiffness of the fill. And by comparing the dissipation at the same dolphin displacement it was found that the denser fill increase the dissipation by 16% for the 20m dolphin and by 23% for the 30m dolphin. The larger sensitivity for the large dolphin is explained by a larger contribution to the dissipation from strain in the fill. In low level impacts the dynamic force-response is up to 26~58% larger than the quasi-static and the dissipation response is showed larger in small displacement. Hence, it is concluded conservative to use the quasi-static response characteristics in the approximation of the response, and it is further concluded that the dolphin resistance to low level impacts is demonstrated to be equivalent and even superior to the high level impacts.

Development of Performance Based Resistance Capacity Evaluation Method for RC Compression Member under Vehicle Impact Load (차량 충돌하중을 받는 RC 압축부재의 성능기반형 저항성능 평가방법 개발)

  • Kim, Jang-Ho Jay;Yi, Na-Hyun;Phan, Duc-Hung;Kim, Sung-Bae;Lee, Kang-Won
    • Journal of the Korea Concrete Institute
    • /
    • v.22 no.4
    • /
    • pp.535-546
    • /
    • 2010
  • Recently, the probability of collision accident between vehicles or vessels and infrastructures are increasing at alarming rate. Particularly, collision impact load can be detrimental to sub-structures such as piers and columns. The damaged pier from an impact load of a vehicle or a vessel can lead to member damages, which make the member more vulnerable to impact load due to other accidents which. In extreme case, may cause structural collapse. Therefore, in this study, the vehicle impact load on concrete compression member was considered to assess the quantitative design resistance capacity to improve, the existing design method and to setup the new damage assessment method. The case study was carried out using the LS-DYNA, an explicit finite element analysis program. The parameters for the case study were cross-section variation of pier, impact load angle, permanent axial load and axial load ratio, concrete strength, longitudinal and lateral rebar ratios, and slenderness ratio. Using the analysis results, the performance based resistance capacity evaluation method for impact load using satisfaction curve was developed using Bayesian probabilistic method, which can be applied to reinforced concrete column design for impact loads.

Analysis on the Characteristics of the Infra-Gravity Waves inside and outside Pohang New Harbor using a Transfer Function Model (전달함수 모형을 이용한 포항신항 내·외의 외중력파 특성 분석)

  • Cho, Hong-Yeon;Jeong, Weon Mu;Oh, Sang-Ho
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.26 no.3
    • /
    • pp.131-139
    • /
    • 2014
  • Infra-gravity waves (IGWs) with a period of 1~3 minutes are a factor that directly influences the motion analysis of moored ships inside a harbor and longshore sediment transport analysis. If significant levels of IGWs from far seas are transferred to a harbor and amplified, they may cause downtime of large ships and induce economic loss. In this study, transfer characteristics of the IGWs intruding from outside to inside Pohang New Harbor were analyzed using statistical analysis and transfer function of wave data measured at both outside and inside the harbor for around 5 years. Transfer characteristic analysis was limited to events where IGWs had wave heights above 0.1 m. The wave height distribution of inside the harbor was similar to that of outside the harbor, while the wave period variance of the former was larger than that of the latter. The parameters of the transfer function was optimally estimated according to each event. The estimated average RMS error of the wave height inside the harbor was around 0.013 m. The estimated parameters had a strong correlation with the linear combination information of IGW wave height, period, and direction (R = 0.95). The transfer function suggested in this study can quickly and easily estimate information on IGWs inside the harbor using IGW information predicted beforehand, and is expected to reduce damage due to unexpected restrictions on harbor usage.

Analysis on the Stress of Hydraulic Cylinder for Large Vessel by Boundary Element Method (대형선박용 유압실린더에서 경제요소법을 이용한 응력해석)

  • 김옥삼
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.31 no.4
    • /
    • pp.423-434
    • /
    • 1995
  • It was used boundary element method(BEM) and analysed axisymmetric problem to solve hydraulic cylinder for large vessel acting uniform internal pressure(25N/m super(2)) within elastic limit. This paper was utilized the carbon steel tubes for machine structural purposed model, inner radius was 150mm and outer radius was 250mm, axial length was semi-infinite and the isoparametric element was used. The important results obtained in this study were summarized as follows. Radial, tangential and shearing stress occured the maximum stresses(48, -20 and 34MPa) at the inner radius and the minimum stresses(32, -4 and 18MPa) at the outer radius of the hydraulic cylinder for large vessel. But negative signs have meaning compressive stress and stress diminution ratio was about 0.15MPa/mm. The use of isoparametric element raised accuracy and the increment of input data lessened the error in internal point but computer run-time was increased. The double node was improved the internal solutions to settle discontinuity at corner and the double exponential formula lessened error of stress value at boundary neighborhood. And then coincidence between the analytical and exact results is found to be fairly good, showing that the proposed analytical by BEM is reliable.

  • PDF

Collapse Analysis of Ultimate Strength Considering the Heat Affected Zone of an Aluminum Stiffened Plate in a Catamaran (카타마란 알루미늄 보강판의 열영향부 효과를 고려한 최종강도 붕괴 해석)

  • Kim, Sung-Jun;Seo, Kwang-Cheol;Park, Joo-Shin
    • Journal of the Korean Society of Marine Environment & Safety
    • /
    • v.26 no.5
    • /
    • pp.542-550
    • /
    • 2020
  • The use of high-strength aluminum alloys for ships and of shore structures has many benefits compared to carbon steels. Recently, high-strength aluminum alloys have been widely used in onshore and of shore industries, and they are widely used for the side shell structures of special-purpose ships. Their use in box girders of bridge structures and in the topside of fixed platforms is also becoming more widespread. Use of aluminum material can reduce fuel consumption by reducing the weight of the composite material through a weight composition ratio of 1/3 compared to carbon steel. The characteristics of the stress strain relationship of an aluminum structure are quite different from those of a steel structure, because of the influence of the welding[process heat affected zone (HAZ). The HAZ of aluminum is much wider than that of steel owing to its higher heat conductivity. In this study, by considering the HAZ generated by metal insert gas (MIG) welding, the buckling and final strength characteristics of an aluminum reinforcing plate against longitudinal compression loads were analyzed. MIG welding reduces both the buckling and ultimate strength, and the energy dissipation rate after initial yielding is high in the range of the HAZ being 15 mm, and then the difference is small when HAZ being 25 mm or more. Therefore, it is important to review and analyze the influence of the HAZ to estimate the structural behavior of the stiffened plate to which the aluminum alloy material is applied.

Evaluation of Waterway Dredging Work using Spud Control System (스퍼드제어시스템을 이용한 항로준설작업의 평가)

  • Lee, Joong-Woo;Jeong, Dae-Deuk;Cho, Jueng-Eon;Oh, Dong-Hoon;Keum, Dong-Ho
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
    • /
    • v.29 no.1
    • /
    • pp.263-271
    • /
    • 2005
  • The most important point when we engage on waterway dredging work is supplying safe navigational passage to the vessels underway by narrowing dredge work area and removing submerged dangers. In order to meet this end it is neccessary to use auxiliary equipment for shifting actively and mooring and adopt automation of dredging work by integrating information on real time position, dredging depth, and work information. The danger with a spud control system in this study, by the way, is able to employed on continuous dredging work with the narrowest working area allowing wide and safe passages to vessels underway, by moving the dredger to the working zone with the spud controlled automatically. Furthermore, it has been improved definitely compared with the existing dredging proccess management system such that it shows the track of spud and working depth on the electronic navigation chart of window, together with the final outcome of dredging work. The test dredging work at the entrance of Busan North Port for system evaluation showed that actual working time available was twice of the one by the existing anchor system, and that it reduced 38% of time for preparation work and one man power.

  • PDF

Reliability Analysis of Ship Deck Structure (선체상갑판의 신뢰성해석)

  • S.J.,Yim;Y.S.,Yang;K.T.,Chung;C.W.,Kim;Y.S.,Suh
    • Bulletin of the Society of Naval Architects of Korea
    • /
    • v.26 no.3
    • /
    • pp.9-20
    • /
    • 1989
  • It is important to enhance the safety of ship structures as much as possible in order to prevent the disastrous collapse of structures. In fact, the strength problem of structures is closely related with the safety problem of structures. Recently, the direct calculation method using a rational approach based on the first principle is implemented into the structural design process instead of adopting empirical approach based on the rules. The structural designer have shown increased concern with the problem of adequacy of conventional design method based on the safety factor since it does not fully take into account some degree of variability of the applied loads on and the strength of ship structures. To deal with the analysis of structures effectively, it is necessary to have three stages being equally treated. The first one is load analysis, second one response analysis, third one safety analysis. For marine structures, most of research effort has been however put into the first and second stages. The third stage is normally done by simple procedures. Hence, the various probabilistic methods are compared in order to establish the reliability analysis techniques for ship structures. As a result, the advanced level 2 method is selected as a most effective and accurate reliability method. The validity of this method is further demonstrated by comparing the results with the conventional method for the problem of the longitudinal strength of hull girder of Ro-Ro ship.

  • PDF

Evaluation of Waterway Dredging Work using Spud Dredge Process Management System (스퍼드 준설선 공정관리시스템을 이용한 항로준설작업의 평가)

  • Lee Joong-Woo;Jeong Dae-Deuk;Cho Jueng-Eon;Kim Ju-Young;Oh Dong-Hoon
    • Journal of Navigation and Port Research
    • /
    • v.29 no.5 s.101
    • /
    • pp.395-402
    • /
    • 2005
  • The most important point when we engage on waterway dredging work is supplying safe navigational passage to the vessels underway by narrowing dredge work area and removing submerged dangers. In order to meet this end it is necessary to use auxiliary equipment for shifting actively and mooring and adopt automation of dredging work by integrating information on real time position, dredging depth, and work information. The dredger with a spud control system in this study, by the way, is able to employed on continuous dredging work with the narrowest working area allowing wide and safe passages to vessels underway, by moving the dredger to the working zone with the spud controlled automatically. Furthermore, it has been improved definitely compared with the existing dredging process management system such that it shows the track of spud and working depth on the electronic navigation chart of window, together with the final outcome of dredging work. The test dredging work at the entrance of Busan North Port for system evaluation showed that actual working time available was twice of the one by the existing anchor system, and that it reduced 38%38% of time for preparation work and one man power.

The Effect of Stress on SCC of Heat Exchanger Tube for LNG Vessel (LNG선박용 열교환기 세관의 SCC에 미치는 응력의 영향)

  • Jeong Hae Kyoo;Lim Uh Joh
    • Journal of the Korean Institute of Gas
    • /
    • v.7 no.2 s.19
    • /
    • pp.22-32
    • /
    • 2003
  • Al-brass material is generally used at the state of plastic deformation, for example; bending, extension of bell mouth at shell and tube type heat exchanger. And SCC(stress corrosion cracking) of Al-brass material will be affected by residual stress as plastic deformation. SCC results from synergism between mechanical factor and corrosion environment. Mechanical factor is stress that directly relates with stress intensity factor at the crack tip. This paper was studied on the effect of stress on SCC of Al-brass tube under in 3.5% NaCl. + 0.1%NH4OH solution by constant displacement tester. Increasing of acidified water flow into sea and speeds up corrosion rate of Al-brass which is used as a tube material of vessel heat exchanger by polluted coast seawater. The experimental results are as follow The latent time of SCC occurrence gets longer as the initial stress intensity factor(KIi) gets lower The main crack was propagated as the initial stress intensity factor(KIi) gets higher, and secondary cracks occurred by electro-chemical factor a(ter stage of released stress. Dezincification phase showed around the crack, and the range of dezincification gets wider as the initial stress intensity factor(KIi) gets higher.

  • PDF

Assessment of the Structural Collapse Behavior of Between Offshore Supply Vessel and Leg in the Jack-up Drilling Rig (잭업드릴링 리그의 레그와 작업 지원선 충돌에 의한 구조붕괴 거동 평가)

  • Park, Joo-Shin;Seo, Jung-Kwan
    • Journal of the Korean Society of Marine Environment & Safety
    • /
    • v.28 no.4
    • /
    • pp.601-609
    • /
    • 2022
  • Jack-up drilling rigs are mobile offshore platforms widely used in the offshore oil and gas exploration industry. These are independent, three-legged, self-elevating units with a cantilevered drilling facility for drilling and production. A typical jack-up rig includes a triangular hull, a tower derrick, a cantilever, a jackcase, living quarters and legs which comprise three-chord, open-truss, X-braced structure with a spudcan. Generally, jack-up rigs can only operate in water depths ranging from 130m to 170m. Recently, there has been an increasing demand for jack-up rigs for operating at deeper water levels and harsher environmental conditions such as waves, currents and wind loads. All static and dynamic loads are supported through legs in the jack-up mode. The most important issue by society is to secure the safety of the leg structure against collision that causes large instantaneous impact energy. In this study, nonlinear FE -analysis and verification of the requirement against collision for 35MJ recommended by DNV was performed using LS-Dyna software. The colliding ship used a 7,500ton of shore supply vessel, and five scenarios of collisions were selected. From the results, all conditions do not satisfy the class requirement of 35MJ. The loading conditions associated with chord collision are reasonable collision energy of 15M and brace collisions are 6MJ. Therefore, it can be confirmed that the identical collision criteria by DNV need to be modified based on collision scenarios and colliding members.