Temperature Effects on FPSO Ultimate Strength: A Reliability Based Approach

2003 ◽  
Author(s):  
Ioannis Moatsos ◽  
Purnendu K. Das
Keyword(s):  
Reliability Analysis ◽  
Ultimate Strength ◽  
Temperature Effects ◽  
Structural Reliability ◽  
Combination Method ◽  
Structural Safety ◽  
Hull Girder ◽  
Reliability Method ◽  
The Subject ◽  
Effects Of Temperature

Structural Reliability analysis is based on probability theory and a significant amount of literature exists on the subject and continues to be a subject of ongoing research. When the structural safety of a ship’s hull is considered, the ultimate hull girder strength should be evaluated. Existing literature on the subject often neglects the effect of temperature. This paper aims to determine the effects of temperature in ship structural reliability and to propose a procedure for analysing structures by taking into account temperature effects. The ultimate strength of the hull girder was calculated using a component approach, where the behaviour of the hull is evaluated based on the behaviour of the single structural components. A sample analysis for Tanker/FPSO structures is provided where the reliability analysis was carried out using a First and Second Order Reliability Method (FORM and SORM) analysis. The loading component was handled using extreme wave statistics and the Ferry Borges-Castanheta load combination method. Annual reliability indices and probabilities of failure were calculated for hogging and sagging conditions showing the effects of temperature along with Partial Safety Factors for all variables taken into account.

Reliability Analysis of Ultimate Strength of a Capesize Bulk Carrier in Hogging and Alternate Hold Loading Condition

2010 ◽  
Author(s):  
Zhi Shu ◽  
Torgeir Moan
Keyword(s):  
Reliability Analysis ◽  
Ultimate Strength ◽  
Loading Condition ◽  
Structural Reliability ◽  
Bulk Carrier ◽  
Local Loads ◽  
Reliability Method ◽  
Bulk Carriers ◽  
Bending Capacity ◽  
Global And Local

This paper deals with the structural reliability analysis (SRA) of ultimate strength of a Capesize bulk carrier in hogging and alternate hold loading condition (AHL). The ultimate strength in hogging and AHL condition is very important for the safety of bulk carriers since the local loads due to internal cargo loads and external sea pressure can reduce the ultimate bending capacity. In the present paper, the characteristic ultimate bending capacity of the subject bulk carrier is investigated by nonlinear finite element (FE) analysis and the characteristic value of the global and local loads are determined in accordance with the Common Structural Rules for bulk carriers (CSR-BC). The uncertainties associated with the loading capacity and load effects are appropriately modelled. The First Order Reliability Method (FORM) is adopted to calculate the annual probability of failure of this bulk carrier in hogging and AHL condition. The effect of heavy weather avoidance on the global and local loads is also evaluated in the SRA. The results show that the local loads have a significant impact on the failure probability of such vessels in the hogging and AHL condition.

The application of Structural Reliability Analysis on hull girder ultimate strength of bulk carriers-a trial on Safety Level Approach

2015 ◽  
Author(s):  
Daokun Zhang ◽  
Wenyong Tang
Keyword(s):  
Reliability Analysis ◽  
Ultimate Strength ◽  
Structural Reliability ◽  
Safety Level ◽  
Hull Girder ◽  
Structural Rules ◽  
Structural Reliability Analysis ◽  
Trial Analysis ◽  
Bulk Carriers ◽  
Partial Safety Factors

The International Maritime Organization is developing the Goal Based Standard, in which the Safety Level Approach(SLA) is one of the two parallel ways forward focusing on deriving explicit and reasonable safety level. During the development of Safety Level Approach, the Structural Reliability Analysis(SRA) is recognized as one of the useful tools. The application of SRA on the calibration of partial safety factors for hull girder ultimate strength is so far a typical illustration, which could be very helpful for the application of Safety Level Approach on the structural Rules in the future. China Classification Society (CCS) carries out a trial analysis with co-operation of Shanghai Jiao Tong University.

scholarly journals RELIABILITY ANALYSIS OF A TWO SPAN FLOOR DESIGNED ACCORDING TO EUROCODE 5

2016 ◽  
Vol 36 (1) ◽  
pp. 18-25
Author(s):  
EN Ogork ◽  
AK Nakore
Keyword(s):  
Reliability Analysis ◽  
Structural Reliability ◽  
Load Ratio ◽  
Structural Safety ◽  
Live Load ◽  
Structural Elements ◽  
Limit States ◽  
Analysis And Design ◽  
Modes Of Failure ◽  
Reliability Method

This paper presents the structural reliability assessment of a two span timber floor of strength class D40 designed in accordance with Eurocode 5 (2004).  The Structural analysis and design of the timber floor system was carried out using deterministic approach, considering both ultimate and serviceability limit states. Reliability analysis of the floor structural elements to ascertain its level of safety was carried out using first order reliability method (FORM) for the four modes of failure of bending shear, bearing and deflection. The reliability analysis involved investigation of the effects of variation of the applied dead to live load ratio and the cross sectional parameters of the floor. The results revealed that the deterministic design is satisfactory as limiting stresses and deflection were not exceeded. The primary floor joists had safety indices in shear and bending of 1.2 to 2.8 with decrease in dead to live load ratio and were below the recommended safety index of 3.8 specified in joint committee on structural safety (JCSS). The timber floor structural elements are more reliable in bearing, shear and deflection and critical in bending mode of failure. The section depth and span of floor elements are more sensitive in bending and deflection modes than shear and bearing modes. http://dx.doi.org/10.4314/njt.v36i1.3

Reliability Analysis of Crane Structure Based on Possibilistic Theory

2013 ◽  
Vol 321-324 ◽  
pp. 1784-1787
Author(s):  
Li Hong Gao ◽  
Shen Quan Liu ◽  
Jing Huang
Keyword(s):  
Reliability Analysis ◽  
Structural Reliability ◽  
Statistical Data ◽  
Possibility Theory ◽  
Structural Safety ◽  
Computational Error ◽  
Sample Collection ◽  
Reliability Method ◽  
Probability Methods ◽  
The Impact

With the increasing for crane in the industrial production, its structural reliability has now been an important concept to guarantee stable performances. The structural safety for the traditional stochastic and probabilistic reliability method is both measured with the viewpoint of probability. But large crane structure with low fault rate is often unable to get necessary statistic data. The new developing crane also has not large amount of statistical data due to no precedent of use. Aiming to these problems, the reliability analysis based on possibility theory is supplied. The method abandons two value state hypotheses, and can avoid a large number of sample collection and the impact of human factors. Compared with the probability methods applied to the crane structure, the possibility reliability method is not only feasible, but also reduces the computational error.

Ultimate Strength and Structural Reliability Analysis of FPSO Hull Girder

2002 ◽  
Author(s):  
Eldho Paul ◽  
Appapillal Thavalingam ◽  
Pumendu K. Das
Keyword(s):  
Reliability Analysis ◽  
Ultimate Strength ◽  
Cross Section ◽  
Structural Reliability ◽  
Strength Analysis ◽  
State Function ◽  
Ultimate Capacity ◽  
Hull Girder ◽  
Structural Reliability Analysis ◽  
Wave Induced

The aim of this paper is to provide some results from an investigation on available simplified formulations for ultimate strength analysis of the gull girder and the possibility of extending these methods in order to couple with reliability computations. This particular study is based on an analytical method proposed by Paik and Mansour. The procedure is enhanced to include structural reliability analysis of FPSOs based on probabilistic approach where uncertainties for both capacity and loading of the structure are taken into account. The estimation of the Ultimate longitudinal capacity and the probability of failure of the FPSO are carried out by dividing the cross section of the hull girder into beam column elements considering the different loads acting on the hull. The limit state function is formulated considering the loads acting on the hull girder and ultimate capacity. The ultimate capacity of the hull is taken as a function of variety of random variable (e.g. area of cross section and yield stresses of the different ship components, etc). The loads acting on the hull girder, both still water and wave induced are calculated using IACS and DNV rules and margins are provided to take care of the long-term deployment of FPSO at sea. Some results from the sensitivity analysis are also provided which has been carried out to study the influence of several factors on the structural reliability of the ship under extreme wave induced bending moment loads.

Structural Reliability Analysis Applied on Steel Ships for Rule Partial Safety Factors Calibration

2017 ◽  
Author(s):  
Alexis Benhamou ◽  
Quentin Derbanne ◽  
Jérôme de Lauzon
Keyword(s):  
Reliability Analysis ◽  
Ultimate Strength ◽  
Structural Reliability ◽  
Bending Moment ◽  
Safety Factors ◽  
Structural Rules ◽  
Structural Reliability Analysis ◽  
Reliability Method ◽  
Partial Safety Factors ◽  
Common Structural Rules

Ultimate strength assessments in current IACS Common Structural Rules (CSR) are determined by a limited number of constant partial safety factors (PSF). These coefficients are inherited from the previous Common Structural Rules for Oil Tankers, and were determined using a structural reliability analysis (SRA) based on a limited number ship. The authors decided to lead a more comprehensive structural reliability analysis to propose and discuss a new set of rule formulations. A literature review is carried out in order to determine an extensive database of virtual ships covering the whole range of existing ships with a few representative parameters. SRA is applied for ultimate strength assessment on this database. Uncertainties are modeled by a set of probability distributions applied to each characteristic quantity (still water bending moment, wave bending moment and capacity) and a Second Order Reliability Method (SORM) is used to target the ultimate capacity corresponding to a given failure probability for each ship. A set of several PSF formulations are then derived from these results using both Working Stress Design (WSD) and Load and Resistance Factor Design (LRFD) approaches. These formulations are then discussed to get an optimum between simplicity and accuracy of the results.

Progressive Collapse Analysis and Reliability of a Damaged Hull Girder

2014 ◽  
Author(s):  
Achinike U. Ibekwe ◽  
YongChang Pu ◽  
Wan L. Ham ◽  
Robert S. Dow
Keyword(s):  
Ultimate Strength ◽  
Structural Reliability ◽  
Numerical Technique ◽  
Progressive Collapse ◽  
Limit State ◽  
Neutral Axis ◽  
Statistical Characteristics ◽  
Structural Safety ◽  
State Function ◽  
Hull Girder

With the expectation of hull girder asymmetry and corresponding shift in elastic neutral axis resulting from collision damages and other forms of structural deteriorations, the interaction of vertical and horizontal hull girder capacities become quite significant in the assessment of ship structural safety. This paper therefore extends the application of a previously proposed interactive-numerical probabilistic based methodology for structural safety to assess the hull girder ultimate strength reliability of a damaged ship by means of a user-defined numerical framework. Hull girder capacity is calculated using the NS94D ultimate strength code, which is based on the Smith’s progressive collapse method. The resulting deterministic responses have been interactively linked to the NESSUS probabilistic framework so that the reliability of the damaged hull girder is predicted using an implicit limit state function defined based on a transformation of coordinates to appropriately account for any shift in the neutral axis. Random deviations of the constituent variables are directly applied to calculate the ultimate strength deterministic responses, thereby circumventing the need to characterize any correlated strength variable, which is at best subjective. The conventional approach of characterizing ultimate strength by an assumed coefficient of variation and distribution type was found to be conservative in predicting structural safety of ships relative to the proposed method. Application of the interactive-numerical technique for structural reliability is therefore considered significant for problems involving correlated random variables with unknown statistical characteristics. The method is being considered to predict the safety of cracked hull girders by accounting for the residual strength and further load bearing capabilities of deteriorated and adjacent elements.

scholarly journals Time-Dependent Reliability Analysis of Reinforced Concrete Beams Subjected to Uniform and Pitting Corrosion and Brittle Fracture

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1820
Author(s):  
Mohamed El Amine Ben Seghier ◽  
Behrooz Keshtegar ◽  
Hussam Mahmoud
Keyword(s):  
Reinforced Concrete ◽  
Brittle Fracture ◽  
Reliability Analysis ◽  
Pitting Corrosion ◽  
Structural Reliability ◽  
Time Dependent ◽  
State Function ◽  
Rc Beams ◽  
Highly Nonlinear ◽  
Reliability Method

Reinforced concrete (RC) beams are basic elements used in the construction of various structures and infrastructural systems. When exposed to harsh environmental conditions, the integrity of RC beams could be compromised as a result of various deterioration mechanisms. One of the most common deterioration mechanisms is the formation of different types of corrosion in the steel reinforcements of the beams, which could impact the overall reliability of the beam. Existing classical reliability analysis methods have shown unstable results when used for the assessment of highly nonlinear problems, such as corroded RC beams. To that end, the main purpose of this paper is to explore the use of a structural reliability method for the multi-state assessment of corroded RC beams. To do so, an improved reliability method, namely the three-term conjugate map (TCM) based on the first order reliability method (FORM), is used. The application of the TCM method to identify the multi-state failure of RC beams is validated against various well-known structural reliability-based FORM formulations. The limit state function (LSF) for corroded RC beams is formulated in accordance with two corrosion types, namely uniform and pitting corrosion, and with consideration of brittle fracture due to the pit-to-crack transition probability. The time-dependent reliability analyses conducted in this study are also used to assess the influence of various parameters on the resulting failure probability of the corroded beams. The results show that the nominal bar diameter, corrosion initiation rate, and the external loads have an important influence on the safety of these structures. In addition, the proposed method is shown to outperform other reliability-based FORM formulations in predicting the level of reliability in RC beams.

Reliability analysis for a hypersonic aircraft’s wing spar

2019 ◽  
Vol 91 (4) ◽  
pp. 549-557
Author(s):  
Yuhui Wang ◽  
Peng Shao ◽  
Qingxian Wu ◽  
Mou Chen
Keyword(s):  
Reliability Analysis ◽  
Structural Reliability ◽  
Strength Degradation ◽  
Structural Safety ◽  
Engineering Practice ◽  
Flight Safety ◽  
Content Type ◽  
Hypersonic Aircraft ◽  
Analysis Scheme ◽  
Wing Spar

Purpose This paper aims to present a novel structural reliability analysis scheme with considering the structural strength degradation for the wing spar of a generic hypersonic aircraft to guarantee flight safety and structural reliability. Design/methodology/approach A logarithmic model with strength degradation for the wing spar is constructed, and a reliability model of the wing spar is established based on stress-strength interference theory and total probability theorem. Findings It is demonstrated that the proposed reliability analysis scheme can obtain more accurate structural reliability and failure results for the wing spar, and the strength degradation cannot be neglected. Furthermore, the obtained results will provide an important reference for the structural safety of hypersonic aircraft. Research limitations/implications The proposed reliability analysis scheme has not implemented in actual flight, as all the simulations are conducted according to the actual experiment data. Practical implications The proposed reliability analysis scheme can solve the structural life problem of the wing spar for hypersonic aircraft and meet engineering practice requirements, and it also provides an important reference to guarantee the flight safety and structural reliability for hypersonic aircraft. Originality/value To describe the damage evolution more accurately, with consideration of strength degradation, flight dynamics and material characteristics of the hypersonic aircraft, the stress-strength interference method is first applied to analyze the structural reliability of the wing spar for the hypersonic aircraft. The proposed analysis scheme is implemented on the dynamic model of the hypersonic aircraft, and the simulation demonstrates that a more reasonable reliability result can be achieved.

scholarly journals Dynamic Reliability Analysis of Corroded Pipeline Using Bayesian Network

2018 ◽  
Vol 7 (4.35) ◽  
pp. 210
Author(s):  
Nurul Sa’aadah Sulaiman ◽  
Henry Tan
Keyword(s):  
Bayesian Network ◽  
Reliability Analysis ◽  
Structural Reliability ◽  
Dynamic Bayesian Network ◽  
Operating Pressure ◽  
Dynamic Reliability ◽  
Time Dynamic ◽  
Remaining Service Life ◽  
Reliability Method ◽  
Deterioration Process

Maintenance and integrity management of hydrocarbons pipelines face the challenges from uncertainties in the data available. This paper demonstrates a way for pipeline remaining service life prediction that integrates structural reliability analysis, accumulated corrosion knowledge, and inspection data on a sound mathematical foundation. Pipeline defects depth grows with time according to an empirical corrosion power law, and this is checked for leakage and rupture probability. The pipeline operating pressure is checked with the degraded failure pressure given by ASME B31G code for rupture likelihood. As corrosion process evolves with time, Dynamic Bayesian Network (DBN) is employed to model the stochastic corrosion deterioration process. From the results obtained, the proposed DBN model for pipeline reliability is advanced compared with other traditional structural reliability method whereby the updating ability brings in more accurate prediction results of structural reliability. The comparisons show that the DBN model can achieve a realistic result similar to the conventional method, Monte Carlo Simulation with very minor discrepancy.

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