Assessment of Structural Reliability of Ships Under Combined Loading Including Extreme Diurnal Temperature Effects

2004 ◽  
Author(s):  
Ioannis Moatsos ◽  
Purnendu K. Das
Keyword(s):  
Climate Change ◽  
Reliability Analysis ◽  
Structural Reliability ◽  
Thermal Stresses ◽  
Practical Importance ◽  
Extreme Temperature ◽  
Stochastic Methods ◽  
Engineering Systems ◽  
Diurnal Temperature ◽  
Load Combination

Research communities of various engineering and physical science fields have in the last year placed a lot of emphasis on modelling the ways climate change affects different engineering systems and therefore influences the methods by which these systems are designed. With a progressive change of our global climate to warmer and more variable conditions worldwide the effects of extreme weather changes are becoming now, more than ever, evident to our everyday lives and affect our safety. It is this effect of climate change that engineers now face the task of incorporating in their design of engineering systems, especially in the ship and offshore-related fields. In such cases of mathematical modelling and analysis variations of more than one variable that is climate dependent can significantly affect the design. The fact that ship structures do encounter temperature conditions that induce thermal stresses and deformation of practical importance has been recognized for some time. The need to develop efficient techniques of modelling extreme environmental phenomena is hence now more relevant than ever in the history of this type of research. A large amount of research exists in the area of extreme wave phenomena and their effects but in terms of extreme temperature and the effect of diurnal temperature changes research published has been very limited. This paper places emphasis on the modelling of loads for use in reliability analysis. Load combination methodology is used for the combination of wave bending, still water, slamming and thermal loads using various stochastic methods for load combination. A case study of an FPSO/Tanker vessel is analysed and diurnal temperature cycles, on structures already in operation in the North Sea/West of Shetland area, are modelled using these load combination techniques. Load combination factors are then introduced for calculating the total hull girder bending moment. Corrosion effects on the structure are modelled using a simple mathematical model derived from actual vessel measurements, statistical analysis and published research. Reliability analysis using a FORM-SORM component approach provides Partial Safety Factors and probabilities of failure.

scholarly journals Influence of Climate Change in Reliability Analysis of High Rise Building

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Yi Zhang ◽  
Keqin Yan ◽  
Tao Cheng ◽  
Quan Zhou ◽  
Liping Qin ◽  
...  
Keyword(s):  
Climate Change ◽  
Reliability Analysis ◽  
Structural Reliability ◽  
Climate Effect ◽  
Existing Building ◽  
Climate Effects ◽  
Urban Structures ◽  
High Rise ◽  
High Rise Building ◽  
Engineering Designs

The safety of designed urban structures is highly depending on the respond of structures to different types and magnitude of environmental loads. The safety assessment of an existing building needs to have a full consideration of all the environmental factors. Therefore, the engineers must realize the importance of the environment and take care of all the assumptions and uncertainties. One of the hot topics that researchers nowadays are interested is the influence of climate change to the engineering designs. There is a remarkable consensus in the scientific community telling us a fact that our climate is changing and engineering design failures are increasing. In this paper, we are going to have an investigation of the effect of the climate change to the safety of high rise building. The climate effects are briefly discussed at the first beginning of this paper. Then a detailed study is performed on the modeling of climate effects for the wind load. This is later utilized in a structural reliability analysis for a high rise building. The influence of climate effects to the overall safety of a building is investigated and discussed based on the analyzed results. It was found the influence of climate effect can be very significant in the design of high rise buildings.

Structural Reliability Applications in Developing Risk-Based Inspection Plans for a Floating Production Installation

2004 ◽  
Author(s):  
A. Ku ◽  
C. Serratella ◽  
R. Spong ◽  
R. Basu ◽  
G. Wang ◽  
...  
Keyword(s):  
Reliability Analysis ◽  
Reliability Index ◽  
Structural Reliability ◽  
Fatigue Behavior ◽  
Statistical Correlation ◽  
Structural Components ◽  
Fatigue Reliability ◽  
Load Combination ◽  
Straightforward Method ◽  
Combination Approach

This paper outlines the essential steps taken in performing structural reliability calculations during the process of laying out a risk-based inspection program. The structural reliability analysis described in this paper essentially takes the deterministic finite element method (FEM) stress/fatigue analysis results, coupled with uncertain degradation mechanisms (e.g. corrosion rate, crack propagating parameters, etc.), and tracks the time-varying structural reliability index of the structural components under consideration. This can then be used to determine the timing for inspection of structural components. For the assessment of structural strength, an efficient and straightforward method is proposed to calculate the time-variant reliability index. This method is verified by an example problem and compared to the random process first-passage reliability solutions. Load combination issue is briefly discussed, in which an approach stems from the ABS Dynamic Loading Approach (DLA) coupled with concepts from Turkstra’s rule. This proposed simplistic load combination approach is verified through an example problem in which the result is compared to the solution calculated from a more sophisticated approach. Establishment of target reliability levels is also briefly discussed. For the assessment of fatigue behavior for welded connections, both S-N curve based and fracture mechanics based reliability methods are discussed. Their usefulness will be discussed in terms of both inspection interval as well as selecting the proper sampling percentage of connections to inspect. Statistical correlation among a group of similar connections is discussed to assist the selection of appropriate locations in the population of the aforementioned sampling. The usefulness of fatigue reliability analysis is also demonstrated by an example problem.

scholarly journals Rising sea levels will reduce extreme temperature variations in tide-dominated reef habitats

2016 ◽  
Vol 2 (8) ◽  
pp. e1600825 ◽  
Author(s):  
Ryan Joseph Lowe ◽  
Xavier Pivan ◽  
James Falter ◽  
Graham Symonds ◽  
Renee Gruber
Keyword(s):  
Sea Level ◽  
Thermal Stresses ◽  
Heat Budget ◽  
Extreme Temperature ◽  
Temperature Extremes ◽  
Sea Levels ◽  
Diurnal Temperature ◽  
Rising Sea Levels ◽  
Heat Budgets ◽  
Using Data

Temperatures within shallow reefs often differ substantially from those in the surrounding ocean; therefore, predicting future patterns of thermal stresses and bleaching at the scale of reefs depends on accurately predicting reef heat budgets. We present a new framework for quantifying how tidal and solar heating cycles interact with reef morphology to control diurnal temperature extremes within shallow, tidally forced reefs. Using data from northwestern Australia, we construct a heat budget model to investigate how frequency differences between the dominant lunar semidiurnal tide and diurnal solar cycle drive ~15-day modulations in diurnal temperature extremes. The model is extended to show how reefs with tidal amplitudes comparable to their depth, relative to mean sea level, tend to experience the largest temperature extremes globally. As a consequence, we reveal how even a modest sea level rise can substantially reduce temperature extremes within tide-dominated reefs, thereby partially offsetting the local effects of future ocean warming.

التغير المناخي واثره في المقنن المائي لمحصول العنب في محافظة ديالى

2019 ◽  
Vol 1 (34) ◽  
pp. 391-422
Author(s):  
اشواق حسن حميد صالح
Keyword(s):  
Climate Change ◽  
Statistical Analysis ◽  
Wind Speed ◽  
Extreme Temperature ◽  
Solar Brightness ◽  
The Subject ◽  
Climate Station ◽  
The Times ◽  
High Level ◽  
Very High

Climate change and its impact on water resources is the problem of the times. Therefore, this study is concerned with the subject of climate change and its impact on the water ration of the grape harvest in Diyala Governorate. The study was based on the data of the Khanaqin climate station for the period 1973-2017, (1986-2017) due to lack of data at governorate level. The general trend of the elements of the climate and its effect on the water formula was extracted. The equation of change was extracted for the duration of the study. The statistical analysis was also used between the elements of the climate (actual brightness, normal temperature, micro and maximum degrees Celsius, wind speed m / s, relative humidity% The results of the statistical analysis confirm that the water ration for the study area is based mainly on the X7 evaporation / netting variable, which is affected by a set of independent variables X1 Solar Brightness X4 X5 Extreme Temperature Wind Speed ​​3X Minimal Temperature and Very High Level .

STRUCTURAL RELIABILITY ANALYSIS BASED ON P-BOXES

2020 ◽  
Vol 92 (6) ◽  
pp. 51-58
Author(s):  
S.A. SOLOVYEV ◽  
Keyword(s):  
Probability Distribution ◽  
Reliability Analysis ◽  
Structural Reliability ◽  
Epistemic Uncertainty ◽  
Random Variable ◽  
Strength Criterion ◽  
Structural Elements ◽  
Structural Element ◽  
Limit States ◽  
Distribution Shape

The article describes a method for reliability (probability of non-failure) analysis of structural elements based on p-boxes. An algorithm for constructing two p-blocks is shown. First p-box is used in the absence of information about the probability distribution shape of a random variable. Second p-box is used for a certain probability distribution function but with inaccurate (interval) function parameters. The algorithm for reliability analysis is presented on a numerical example of the reliability analysis for a flexural wooden beam by wood strength criterion. The result of the reliability analysis is an interval of the non-failure probability boundaries. Recommendations are given for narrowing the reliability boundaries which can reduce epistemic uncertainty. On the basis of the proposed approach, particular methods for reliability analysis for any structural elements can be developed. Design equations are given for a comprehensive assessment of the structural element reliability as a system taking into account all the criteria of limit states.

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.

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