scholarly journals Approximated Evaluation of Failure Probability for Structural System Using Conditional Safety Indices.

1996 ◽  
Vol 62 (602) ◽  
pp. 2379-2386
Author(s):  
Shingo NAKANISHI ◽  
Hidetoshi NAKAYASU
Keyword(s):  
Failure Probability ◽  
Structural System ◽  
Safety Indices ◽  
Approximated Evaluation

scholarly journals Addition laws of failure probability and their applications in reliability analysis of structural system with multiple failure modes

2012 ◽  
Vol 227 (1) ◽  
pp. 120-136 ◽  
Author(s):  
Pengfei Wei ◽  
Zhenzhou Lu ◽  
Longfei Tian
Keyword(s):  
Linear Programming ◽  
Failure Mode ◽  
Failure Probability ◽  
Failure Modes ◽  
Programming Model ◽  
Small Scale ◽  
Structural System ◽  
Third Order ◽  
Multiple Failure Modes ◽  
Basic Principles

Compared with the methods solving failure probability of the structural system with multiple failure modes, those solving failure probability of a single failure mode are simpler and more well-developed, thus in order to employ the latter to establish the former, the addition laws of the failure probability are derived mathematically by use of the basic principles of probability theory. In the derived addition laws, the failure probability of the structural system with n failure modes is expressed as a combination of the failure probabilities of 2 n−1 single failure modes. Therefore, the failure probability of the structural system with multiple failure modes can be solved by the well-developed methods for the failure probability of a single failure mode. After reviewing the boundary theories, such as the second-order boundary, the third-order boundary, and the linear programming based boundary for analyzing the failure probability of the structural system with multiple failure modes, the derived addition laws are applied to evaluate several former order joint failure probability involved in those boundary theories. Additionally, a new small-scale linear programming based boundary theory which can sufficiently reduce the scale of the linear programming model involved is proposed. Two numerical examples, including a series and a parallel structural system, are employed to demonstrate the accuracy and efficiency of proposed techniques.

Discussion of Reliability Analysis for Aircraft Wing Box Structural System

2010 ◽  
Vol 118-120 ◽  
pp. 236-240
Author(s):  
Wei Tao Zhao ◽  
Da Qian Zhang
Keyword(s):  
Reliability Analysis ◽  
Failure Probability ◽  
Structural Reliability ◽  
Random Variable ◽  
Complex Problem ◽  
Structural System ◽  
Aircraft Wing ◽  
Failure Path ◽  
First Order Second Moment ◽  
Wing Box

It is very complex problem that the reliability of aircraft wing box structural system with many random variables (such as area, thickness, material modulus, load etc.) is analyzed. In the paper, the reliability analysis method of aircraft wing box structural system is proposed based on the theory of structural reliability and stochastic finite element. The explicit expression of safe margin and the sensitivity of safe margin to each random variable are given, which improves the accuracy and efficiency of reliability calculation. The relationship of the level of failure path with structural system failure probability is discussion. The failure probability of element is calculated by using first order second moment method, and the main failure path of structural system is identified by using the advanced branch and bound method, and the failure probability of structural system is evaluated by using probabilistic network evaluation technique method. Numerical examples show that the method is of efficient and accurate, and the 3 or 4 level of failure path is acceptable for wing box structural system considering efficiency and accuracy.

Reliability analysis of structural system with multiple failure modes and mixed uncertain input variables

2012 ◽  
Vol 227 (7) ◽  
pp. 1441-1453 ◽  
Author(s):  
Pengfei Wei ◽  
Zhenzhou Lu ◽  
Bo Ren
Keyword(s):  
Linear Programming ◽  
Failure Probability ◽  
Failure Modes ◽  
Structural System ◽  
Multiple Failure Modes ◽  
Random Inputs ◽  
Numerical Examples ◽  
Input Variables ◽  
Uncertain Input ◽  
The Membership Function

In the design of engineering structure, uncertainties can be modeled as randomness or fuzziness depending on the amount of information available. In this article, the estimation of failure probability of structural system with multiple failure modes and mixed (random and fuzzy) inputs is considered. We firstly review the addition law of failure probability and a linear programming based bound method, and then these two techniques are combined to deal with structural system with multiple failure modes and only random inputs. Eventually, this method is extended for estimating the membership function of the failure probability of structural system with both random and fuzzy inputs. This method is computationally cheap, especially for the structural system with a large number of failure modes. Several numerical examples are introduced for demonstrating the efficiency and accuracy of the proposed method.

Efficient Reliability Analysis Using Multipoint Response Surface Method

2007 ◽  
Author(s):  
B. N. Rao ◽  
Rajib Chowdhury ◽  
A. Meher Prasad
Keyword(s):  
Reliability Analysis ◽  
Response Surface ◽  
Response Surface Method ◽  
Failure Probability ◽  
Structural System ◽  
Performance Function ◽  
Numerical Examples ◽  
Simplified Approach ◽  
Surface Method ◽  
Complex Structural

In the reliability analysis of complex structural system, to approximate the performance function accurately, the most common approach is Response Surface Method. Response surface is usually constructed around the design point, for better approximation of the performance function. Existence of multiple design points accelerates the difficulty of approximating the performance function. This paper presents i) a simplified approach for identifying the existence of multiple design points/or regions on the limit surface which have significant contributions to the failure probability and ii) a newly developed concept of multipoint response surface. Identification of multiple design points is based on a weight function, which can provide the weighting index of sampling points. Failure probability can be estimated by constructing multipoint response surface around the identified pints. In addition to the effort of identifying the region of importance, the method requires a small number of exact or numerical evaluations of the performance function at selected inputs. Numerical examples show the accuracy and efficiency of the proposed approach.

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.

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