Volume 3: Structures, Safety, and Reliability最新文献

{"title":"Random Combination Factors for Still Water and Wave Bending Moments","authors":"Wenbo Huang","doi":"10.1115/omae2019-96665","DOIUrl":"https://doi.org/10.1115/omae2019-96665","url":null,"abstract":"\u0000 Based on the extreme value of the primary loads of ship hull girder instead of characteristic values, the more reasonable load combination factors are defined. In order to evaluate the random variation of newly defined load combination factors, based on Ferry-Berges & Castanheta (FBC) and Poisson square wave models, the still water bending moments (SWBM), vertical wave bending moments (VWBM) and their combined processes are simulated to get the random realizations of load combination factors. The statistical analysis results show that the load combination factors take the value of 1 with the highest probability and can be well fitted by the Weibull distribution. Such information should be incorporated appropriately in the reliability analysis of ship hull girder.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"411 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134038943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fatigue of Mooring Chains Connected to Offshore Floating Structures Considering Out of Plane Bending Effects","authors":"Vidar Hellum, S. Ding, T. Lassen","doi":"10.1115/omae2019-96114","DOIUrl":"https://doi.org/10.1115/omae2019-96114","url":null,"abstract":"\u0000 Reliability against fatigue fracture is an issue of major concern in the design of offshore mooring systems with chain segments. The present paper describes the investigation of the effect of OPB (out of plane bending) and IPB (in plane bending) loading modes on the fatigue performance of chain links in critical positions. The hang-off design at the floater is based on long rods with bearings at the connection points to the floating structure. The purpose of the paper is to shed some light on possible design improvements on the connection design when using the available design guidelines for calculation of combined Tension-Bending fatigue in the mooring line.\u0000 A challenge when using the existing design guidelines is that they often predict very short fatigue lives for what used to be a conventional hang-off design. A possible method for mitigating this is to improve the connection design so that the interlink angles could be reduced due to the slip in the bearings in the end of the rod. This would lower the bending stress to be occurred in those critical links. The present paper investigates the optimum length connecting rods and friction in the bearing on the fatigue lives of top mooring chains.\u0000 A case study for 125 mm mooring chain and a pretension of 1200 kN is included. A non-linear beam model established according to the BV guidelines showed good ability to model the behavior of the 125 mm chain observed during the test. It is however a challenge to select the right interlink rotational stiffness and the correct bearing friction coefficient. An optimization analyses demonstrated that a rod length should be minimum 3 meters and the friction coefficient should be down to 0.15.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"54 22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121029325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Elementary Loading Processes and Scale Effects Involved in Wave-in-Deck Type of Loading: A Summary of the BreaKin JIP","authors":"J. Scharnke","doi":"10.1115/omae2019-95004","DOIUrl":"https://doi.org/10.1115/omae2019-95004","url":null,"abstract":"\u0000 To quantify the loading due to breaking waves, model tests are currently the option of choice. However, it is suspected that scale effects lead to an overestimation of the prototype loading. As such, a typical question in impact load assessment is how conservative load measurements are. To understand how realistic model testing is in this respect, it is necessary to quantify scale effects in the measured loading due to breaking waves as well as to investigate to which extent entrapped air in the wave and during the wave impact is involved. To do so, the BreaKin Joint Industry Project was started in 2016. The objective of the BreaKin JIP was to get more insight into scale effects involved in wave-in-deck model tests and to take first steps towards linking wave kinematics with measured impact loads.\u0000 During this JIP wave-in-deck model tests were carried out in MARIN’s Depressurized Wave Basin (DWB) at two scales (25 and 50) in atmospheric and depressurized condition. This paper gives an overview of the results of the BreaKin JIP regarding loading processes involved in wave-in-deck type of impacts, effects of depressurization on measured loads and possible sources of scale effects.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129269047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mean Load Impact on Mooring Chain Fatigue Capacity: Lessons Learned From Full Scale Fatigue Testing of Used Chains","authors":"Ø. Gabrielsen, K. Larsen, Oddgeir Dalane, Hans B. Lie, Svein-Arne Reinholdtsen","doi":"10.1115/omae2019-95083","DOIUrl":"https://doi.org/10.1115/omae2019-95083","url":null,"abstract":"\u0000 Fatigue of mooring chain is for many floating offshore installations a limiting factor in design. With aging installations and the need for field life extension beyond the original design life, questions on mooring chain endurance are raised. Current SN curves utilized in fatigue limit state (FLS) calculation are based on full scale testing of new chain, performed at a high mean load level (20% of the chains minimum breaking load (MBL)). The high mean load level in the tests do not correspond to the conditions for many chains in operation, as mean load in fatigue relevant seastates are often significantly less than mean load used in the new chain fatigue tests. Mooring chains in operation also experience different degree of corrosion, both general corrosion and pitting. Surface roughness and corrosion pits contribute to crack initiations, and thus reduce fatigue capacity. Fatigue tests with new chain condition cannot be assumed representative for corroded chains.\u0000 As part of mooring integrity programs, Equinor has been replacing mooring chains since year 2000. To assess actual fatigue capacity, many chain segments have been full scale fatigue tested. First tests started in 2011, and the tests cover different degrees of corrosion. The tests have been performed at typical mean load levels relevant for operation of the installations, which for most cases are less than 20%MBL. From these tests it is observed that fatigue capacity in some cases are better than expected for new chain, even for chain segments with significant corrosion. Fatigue test results show a large effect of the mean load. For test cases with significant corrosion and high mean load (20%MBL), a significant reduction in fatigue capacity compared to new chains is found.\u0000 This paper presents some of the fatigue test results on used chain, highlighting the effect of the mean load for the given chain conditions. Effect of corrosion at mean load of 20%MBL is also included. The paper discusses some of the underlaying causes for the mean load dependency.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"119 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129313393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Risk Assessment of Ship Systems Based on Forward FTF Method","authors":"S. Mai, J. Zeng, Qi Feng, Renan Liu, Yuanchun Chen","doi":"10.1115/omae2019-95320","DOIUrl":"https://doi.org/10.1115/omae2019-95320","url":null,"abstract":"\u0000 Ocean-going vessels sailing alone in the boundless sea often encounter various problems and pose a serious threat to the safety of the ship. According to statistic, many of these accidents are caused by problems such as aging equipment and lack of maintenance. After IMO issued mandatory regulations, China Classification Society (CCS) released Failure Mode and Impact Analysis Guide in 2017 (Guidance Notes GD16-2017), in connection with failure mode and impact analysis for ship equipment and systems. In this paper, based on a multi-purpose offshore carrier, the forward FTF (FMECA & FTA) method is adopted. The failure mode, effects and criticality analysis (FMECA) is conducted for the study on failure mode of ship system, including failure rate, cause and effect (probability and severity). Fault tree analysis (FTA) is to calculate and assess the risk of the ship system. Based on the forward FTF principle, Smart Captain, an operation and maintenance management system was developed for this ship. The system can identify the faults of the ship system and carry out different levels of alarms automatically, then a corresponding maintenance and operation instructions according to the equipment manual is given. By using Smart Captain, the crew member can carry out ship operation and maintenance efficiently safely.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"316 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133338100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Simulation of Container Stacks Dynamics Under Typical Motion Excitation","authors":"Chuntong Li, De-yu Wang, Jiaqi Liu","doi":"10.1115/omae2019-95644","DOIUrl":"https://doi.org/10.1115/omae2019-95644","url":null,"abstract":"\u0000 Present regulation and norms for securing equipment are calculated based on static strength analysis ignore the dynamic situations faced by containers during maritime transportation, and the event of container loss still occurs. This research aim to investigate the dynamic behavior of container stack under typical motion excitations simulating real ocean conditions. A two-tier scaled model of a 20-ft ISO freight container were built based on scaling law. The research process is divided into three stages. The first stage: establish a full-scale 20-ft container mode, and obtain characteristic information such as mass and stiffness through finite element analysis. In the second stage, the multi-objective optimization algorithm is used to establish the scale model of the container, and the scale model of the design is verified. In the third stage, the finite element method is used to further understand the influence of each design variables on the dynamic response of container stack. Under different motion excitations, the influence of each basic variables on the structural response and the load change on the critical points of the structure are determined. Meanwhile, the results of this study also show that the mathematical model constructed is effective and can reasonably predict the actual situation of container stacks stored on the ship’s deck.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129606894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamic Load Inversion Method of Ship Body Based on Influence Coefficient Matrix","authors":"H. Ren, G. Feng, Liu Hao, Xuecong Hu, Jian Zou","doi":"10.1115/omae2019-95777","DOIUrl":"https://doi.org/10.1115/omae2019-95777","url":null,"abstract":"\u0000 Ships sail in complex marine environments, the load is complex and uncertain. In the actual hull strength analysis, hull health monitoring and diagnosis, structural optimization design and other issues, it is very important to determine or estimate the dynamic load which applied on the hull structure. Due to the complexity and uncertainty of the working environment of the ship, many dynamic loads such as slamming loads applied on the bow of the hull are impossible or difficult to be measured directly. However, the structural response (strain, displacement, acceleration, etc.) of the corresponding part and other system characteristic parameters such as natural frequency, vibration mode, damping ratio, etc. can be obtained by installing sensors. Using the dynamic response of the structure, combined with the load identification model, the dynamic load on the hull can be calculated reversely. The time domain method and the frequency domain method are currently the most commonly used methods on load inversion. The time domain method is very suitable for the inversion identification problem of non-stationary loads and impact loads. The solution is intuitive and easy to use. In this paper, on based the time domain method, for the non-transient dynamic load, the displacement and time orthogonal function basis functions are loaded on the structure as the load function, and the response of the structure is obtained. The influence coefficient matrix is established by the response, and then the inversion load function is fitted; For transient dynamic loads such as slamming load, unit pulse load is applied on the structure to obtain the response of the structure. Then the corresponding data are filtered to overcome the ill-conditioned matrix problem. The matrix of the influence coefficient is established by the response, and the dynamic load is obtained. The two methods of dynamic load inversion based on the influence coefficient matrix are verified by numerical examples. The error is within a reasonable range, which proves that the inversion method is feasible.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123437680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on the Effect of Impact Load Generated From Pile Driving on Adjacent Berthing Structure","authors":"J. John, N. Saha, R. Sundaravadivelu","doi":"10.1115/omae2019-96092","DOIUrl":"https://doi.org/10.1115/omae2019-96092","url":null,"abstract":"\u0000 The extension of ports and offshore structures has increased due to feasible marine transportation with more cargoes pouring into the ports across the world. In many ports, there is limited availability of favourable conditions to berth and lack of space for an extension. This leads to the construction of new berthing structures at very close vicinity to existing structures which are aged but significant. One prime concern in such berths is the vibration that will be transmitted to the existing old structure during the construction of the new one. Therefore there is a requirement to keep vibration effects under control to ensure that existing structures remain serviceable.\u0000 One of the scenarios that determine the intensity of vibration that will be transmitted to soil and adjacent structure is the impact load applied on the pile. In the paper, the study is chosen at a specific port which needs reconstruction and extension due to the change in nature of the cargo to be handled and its requirements and also due to deterioration of aged berthing structure. Therefore, this study aims to find out the effect of impact load that is applied on pile casing during the pile driving process, so that the adjacent structure and machinery can be kept serviceable. The structure, soil medium and pile driving process are modelled in PLAXIS 3D. A damping ratio of 5 percent is assumed for both structure and soil throughout the modelling. A parametric study is done by varying the load on the pile casing while pile driving. The study gives the response of the structure to dynamic loading and influence of load on peak particle velocity during pile driving that gives economical piling and also ensures the safety of the adjacent berthing structure.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125834043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Non-Repeatability, Scale- and Model Effects in Laboratory Measurement of Impact Loads Induced by an Overtopped Bore on a Dike Mounted Wall","authors":"M. Streicher, A. Kortenhaus, C. Altomare, S. Hughes, Krasimir Marinov, B. Hofland, Xuexue Chen, Tomohiro Suzuki, L. Cappietti","doi":"10.1115/omae2019-96703","DOIUrl":"https://doi.org/10.1115/omae2019-96703","url":null,"abstract":"\u0000 Overtopping bore impact forces on a dike mounted vertical wall were measured in similar large-scale (Froude length scale factor 1-to-4.3) and small-scale (Froude length scale factor 1-to-25) models. The differences due to scale effects were studied, by comparing the up-scaled force measurements from both models in prototype. It was noted that if a minimum layer thickness, velocity of the overtopping flow and water depth at the dike toe were maintained in the small-scale model, the resulting differences in impact force due to scale effects are within the range of differences due to non-repeatability and model effects.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116221485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On Disaster Risk Reduction in Norwegian Oil and Gas Industry Through Life-Cycle Perspective","authors":"Mihaela Ibrion, N. Paltrinieri, A. Nejad","doi":"10.1115/omae2019-95622","DOIUrl":"https://doi.org/10.1115/omae2019-95622","url":null,"abstract":"\u0000 This paper presents the risk reduction in Norwegian oil & gas industry over the time (1975–2016) through a life cycle perspective analysis with the aim to identify the critical stage(s) both in terms of accident occurrence and cause of the accident. Fifteen accidents, major accidents and disasters for example Ecofisk 2/4 Alpha 1975, Alexander L. Kielland 1980, Songa Endurance 2016 were studied. Cases from outside of the Norwegian offshore field — the Piper Alpha 1988, the Bourbon Dolphin 2007, and the Deep Water Horizon 2010 — were also considered as comparison. For each accident and through the life cycle analysis, the occurrence stage of the accident and its main technical causes were identified and compared. It was found that a high risk is concentrated in the Operation (In-Service) stage and associated Marine Operations. Furthermore, it was observed that a high number of accidents in oil and gas industry are associated with mobile structures. All the investigated accidents have acted as powerful reminders to the oil and gas industry that a continuous improvement of risk management and reduction of uncertainty are of paramount importance in order to ensure safe operations and risk reduction for accidents, major accidents and disasters. However, a reactive learning from major accidents and disasters needs to be supported by a proactive learning and development of a dynamic risk culture in the oil and gas industry.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114647982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}