Foundation Safety of Gravity-Based Systems During Severe Storms

1992 ◽  
Vol 114 (2) ◽  
pp. 104-113
Author(s):  
K. O. Ronold ◽  
S. Haver
Keyword(s):  
Failure Probability ◽  
Load Factor ◽  
Structural System ◽  
Sea State ◽  
First Order Reliability Method ◽  
Severe Storms ◽  
First Order ◽  
Reliability Method ◽  
Northern North Sea ◽  
The Stability

The temporal evolutions of the most important sea state characteristics during storms are presented together with the corresponding uncertainties. Storm data from the Northern North Sea are used for this purpose. The influence of the uncertainties associated with an extreme storm on the foundation safety is demonstrated for a gravity-based structural system founded on a clay. The stability is analyzed with respect to failure in large cyclic displacements accumulated during the storm. The failure probability is estimated by a first-order reliability method and the most important variables concerning their contribution to the failure probability are indicated. In most practical foundation safety investigations, an idealized deterministic storm profile is adopted. The adequacy of this profile is considered by calibrating a “load factor” to be used in connection with the idealized profile.

Reliability Estimation of Buried Pipeline Using FORM, SORM and Monte Carlo Simulation

2006 ◽  
Vol 326-328 ◽  
pp. 597-600 ◽  
Author(s):  
Ouk Sub Lee ◽  
Dong Hyeok Kim
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Exposure Time ◽  
Failure Probability ◽  
Reliability Estimation ◽  
Buried Pipeline ◽  
First Order Reliability Method ◽  
First Order ◽  
Reliability Method ◽  
The Difference

In this paper, the failure probability is estimated by using the FORM (first order reliability method), the SORM (second order reliability method) and the Monte Carlo simulation to evaluate the reliability of the corroded pipeline. It is found that the FORM technique is more effective in estimating the failure probability than the SORM technique for B31G and MB31G models with three different corrosion models. Furthermore, it is noted that the difference between the results of the FORM, the SORM and the Monte Carlo simulation decreases with the increase of the exposure time.

An accuracy analysis method for first-order reliability method

2018 ◽  
Vol 233 (12) ◽  
pp. 4319-4327 ◽  
Author(s):  
Zhenzhong Chen ◽  
Zihao Wu ◽  
Xiaoke Li ◽  
Ge Chen ◽  
Guangfeng Chen ◽  
...  
Keyword(s):  
Structural Reliability ◽  
Nonlinear Problems ◽  
Accuracy Analysis ◽  
Analysis Method ◽  
First Order Reliability Method ◽  
First Order ◽  
Reliability Level ◽  
Reliability Method ◽  
Value Range ◽  
Crashworthiness Design

The first-order reliability method is widely used for structural reliability analysis; however, its accuracy would become worse for nonlinear problems. This paper proposes the accuracy analysis method of the first-order reliability method, which considers the worst cases when using the first-order reliability method and gives the possible value range of the probability of safety. The accuracy analysis method can evaluate the reliability level of the first-order reliability method when the failure surfaces are nonlinear. The calculation formula for the possible value range of the probability of safety is proposed, and its trend as the dimensions and reliability rise is also discussed in this paper. A numerical example and a honeycomb crashworthiness design are presented to validate the accuracy of the first-order reliability method, and the results show that they are located within the possible value range proposed in this paper.

Reliability of Buried Pipeline Using a Theory of Probability of Failure

2006 ◽  
Vol 110 ◽  
pp. 221-230 ◽  
Author(s):  
Ouk Sub Lee ◽  
Dong Hyeok Kim ◽  
Seon Soon Choi
Keyword(s):  
Failure Probability ◽  
Probability Of Failure ◽  
Operating Conditions ◽  
Reliability Estimation ◽  
Design Parameters ◽  
Buried Pipeline ◽  
Safety Level ◽  
First Order ◽  
Reliability Method ◽  
Corrosion Defects

The reliability estimation of buried pipeline with corrosion defects is presented. The reliability of corroded pipeline has been estimated by using a theory of probability of failure. And the reliability has been analyzed in accordance with a target safety level. The probability of failure is calculated using the FORM (first order reliability method). The changes in probability of failure corresponding to three corrosion models and eight failure pressure models are systematically investigated in detail. It is highly suggested that the plant designer should select appropriate operating conditions and design parameters and analyze the reliability of buried pipeline with corrosion defects according to the probability of failure and a required target safety level. The normalized margin is defined and estimated accordingly. Furthermore, the normalized margin is used to predict the failure probability using the fitting lines between failure probability and normalized margin.

Vibration Fatigue Reliability of Lead and Lead-Free Solder Joint by FORM/SORM

2007 ◽  
Vol 345-346 ◽  
pp. 1393-1396
Author(s):  
Ouk Sub Lee ◽  
Man Jae Hur ◽  
Yeon Chang Park ◽  
Dong Hyeok Kim
Keyword(s):  
Solder Joint ◽  
Failure Probability ◽  
Lead Free ◽  
Lead Free Solder ◽  
Fatigue Reliability ◽  
Probability Models ◽  
First Order ◽  
Reliability Method ◽  
Vibration Fatigue ◽  
Free Solder

It is well-known that the vibration significantly affect the life of solder joint. In this paper, the effects of the vibration on the failure probability of the solder joint are studied by using the failure probability models such as the First Order Reliability Method (FORM) and the Second Order Reliability Method (SORM). The accuracies of the results are estimated by a help of the Monte Carlo Simulation (MCS). The reliability of the lead and the lead-free solder joint was also evaluated. The reliability of lead-free solder joint is found to be higher than that of lead solder joint.

Sensitivity of Vessel Responses to Environmental Contours of Extreme Sea States

2015 ◽  
Author(s):  
Curtis Armstrong ◽  
Christopher Chin ◽  
Irene Penesis ◽  
Yuriy Drobyshevski
Keyword(s):  
Case Studies ◽  
Return Period ◽  
Significant Wave Height ◽  
Peak Period ◽  
First Order Reliability Method ◽  
First Order ◽  
Long Wave ◽  
Contour Lines ◽  
Reliability Method ◽  
Extreme Responses

A comparative study of two methods for the generation of the environmental contours is presented investigating the sensitivity of the predicted extreme vessel responses to the type of the contour lines. Two approaches for the generation of environmental contours of the significant wave height and peak period are compared: the Inverse First Order Reliability Method (IFORM) and Constant Probability Density (CPD) approach. Case studies include several global responses of a ship-shaped weather-vaning vessel and a semisubmersible platform. The case studies reveal that the differences between the IFORM and CPD contours are more pronounced in the range of long wave periods. Vessel responses which are less sensitive to long wave periods exhibit less difference (less than 1.0%) in their maximum values between the two types of contours. In contrast, responses which are sensitive to long wave periods show significantly larger differences of up to 7.0%. Uncertainties also exist in the predicted extreme responses where the environmental contour and the response isoline behave tangentially. Differences between the extreme responses produced by the two contours generally decrease with an increase in return period; however exceptions exist due to the tangential behaviour. It is advised that these sensitivities should be taken into consideration when the environmental contours are used in the design.

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