Probabilistic modelling of safety and damage blast risks for window glazingThis paper is one of a selection of papers in the Special Issue on Blast Engineering.

2009 ◽  
Vol 36 (8) ◽  
pp. 1321-1331 ◽  
Author(s):  
Michael D. Netherton ◽  
Mark G. Stewart
Keyword(s):  
Structural Reliability ◽  
Risk Mitigation ◽  
Forensic Analysis ◽  
System Response ◽  
Computational Techniques ◽  
Limit States ◽  
Response Planning ◽  
Blast Response ◽  
Extent Of Damage ◽  
The Uk

There are many computational techniques to model the consequences to built infrastructure when subject to explosive blast loads; however, the majority of these do not account for the uncertainties associated with system response or blast loading. This paper describes a new computational model, called “Blast-RF” (Blast Risks for Facades), that incorporates existing (deterministic) blast-response models within an environment that considers threat and (or) vulnerability uncertainties and variability using probability and structural reliability theory. The structural reliability analysis uses stress limit states and the UK Glazing Hazard Guide's rating criteria to calculate probabilities of glazing damage and occupant safety hazards conditional on a given blast scenario. This allows the prediction of likelihood and extent of damage and (or) casualties, useful information for risk mitigation considerations, emergency service's contingency and response planning, collateral damage estimation, weaponeering, and post-blast forensic analysis.

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 Enabling Technologies for Improved Data Management: Hardware

2001 ◽  
Vol 9 (1) ◽  
pp. 11-25
Author(s):  
Kerstin van Dam-Kleese ◽  
Michael Hopewell
Keyword(s):  
Data Management ◽  
Scientific Community ◽  
Wide Spectrum ◽  
Work Force ◽  
Working Environment ◽  
Computational Techniques ◽  
Enabling Technologies ◽  
New Challenges ◽  
The Uk ◽  
The Right

The most valuable assets in every scientific community are the expert work force and the research results/data produced. The last decade has seen new experimental and computational techniques developing at an ever-faster pace, encouraging the production of ever-larger quantities of data in ever-shorter time spans. Concurrently the traditional scientific working environment has changed beyond recognition. Today scientists can use a wide spectrum of experimental, computational and analytical facilities, often widely distributed over the UK and Europe. In this environment new challenges are posed for the Management of Data every day, but are we ready to tackle them? Do we know exactly what the challenges are? Is the right technology available and is it applied where necessary? This part of enabling technologies investigates current hardware techniques and their functionalities and provides a comparison between various products.

Influence of Human Error on Structural Reliability

2017 ◽  
Author(s):  
Eric Brehm ◽  
Robert Hertle ◽  
Markus Wetzel
Keyword(s):  
Human Error ◽  
Structural Reliability ◽  
Failure Modes ◽  
Structural Model ◽  
Limit State ◽  
Design Procedure ◽  
Material Strength ◽  
Limit States ◽  
The Impact

In common structural design, random variables, such as material strength or loads, are represented by fixed numbers defined in design codes. This is also referred to as deterministic design. Addressing the random character of these variables directly, the probabilistic design procedure allows the determination of the probability of exceeding a defined limit state. This probability is referred to as failure probability. From there, the structural reliability, representing the survival probability, can be determined. Structural reliability thus is a property of a structure or structural member, depending on the relevant limit states, failure modes and basic variables. This is the basis for the determination of partial safety factors which are, for sake of a simpler design, applied within deterministic design procedures. In addition to the basic variables in terms of material and loads, further basic variables representing the structural model have to be considered. These depend strongly on the experience of the design engineer and the level of detailing of the model. However, in the clear majority of cases [1] failure does not occur due to unexpectedly high or low values of loads or material strength. The most common reasons for failure are human errors in design and execution. This paper will provide practical examples of original designs affected by human error and will assess the impact on structural reliability.

Limit State of Torsion of Ship Hulls with Large Hatch Openings

2001 ◽  
Vol 45 (02) ◽  
pp. 95-102
Author(s):  
Yuren Hu ◽  
Bozhen Chen
Keyword(s):  
Cross Section ◽  
Structural Reliability ◽  
Limit State ◽  
Safety Margin ◽  
Plastic Shear ◽  
Torsional Moment ◽  
Limit States ◽  
Ship Hulls ◽  
Design Values ◽  
Bound Theorem

The limit state of torsion of ship hulls with large hatch openings is studied. A method to determine the distribution of the plastic shear flow on the hull cross section in the limit state by using the lower-bound theorem is presented together with the corresponding linear programming problem. The limit torsional moment of the hull cross section is obtained based on the distribution of the shear stress in the limit state. Three example limit states for typical containerships of different sizes with large hatch openings are calculated. The calculated limit torsional moments are compared with the design values of wave torque calculated by using the equations given by main classification societies in their rules. A rough estimate of the safety margin is obtained. The results show that for large containerships, it is necessary to pay attention to the safety with respect to torsion. The present method can serve as an effective tool in structural reliability analysis of ships with large hatch openings when the failure mode of torsion is taken into account.

scholarly journals Calibrating Partial Factors – Methodology, Input Data and Case Study of Steel Structures

2019 ◽  
Author(s):  
Vitali Nadolski ◽  
Árpád Rózsás ◽  
Miroslav Sýkora
Keyword(s):  
Input Data ◽  
Structural Reliability ◽  
Construction Materials ◽  
Steel Structures ◽  
Structural Performance ◽  
Limit States ◽  
Different Types ◽  
Load Effects ◽  
Previous Design

Partial factors are commonly based on expert judgements and on calibration to previous design formats. This inevitably results in unbalanced structural reliability for different types of construction materials, loads and limit states. Probabilistic calibration makes it possible to account for plentiful requirements on structural performance, environmental conditions, production and execution quality etc. In the light of ongoing revisions of Eurocodes and the development of National Annexes, the study overviews the methodology of probabilistic calibration, provides input data for models of basic variables and illustrates the application by a case study. It appears that the partial factors recommended in the current standards provide for a lower reliability level than that indicated in EN 1990. Different values should be considered for the partial factors for imposed, wind and snow loads, appreciating the distinct nature of uncertainties in their load effects.

Reduction Factors for Estimating the Probability of Failure of Mechanical Damage Due to External Interference

2008 ◽  
Author(s):  
Andrew Cosham ◽  
Jane Haswell ◽  
Neil Jackson
Keyword(s):  
Structural Reliability ◽  
Historical Data ◽  
Mechanical Damage ◽  
Probability Of Failure ◽  
Risk Assessments ◽  
External Interference ◽  
Failure Data ◽  
Major Accident ◽  
The Uk ◽  
Reduction Factors

Quantified risk assessments (QRAs) are widely used in the UK to assess the significance of the risk posed by major accident hazard pipelines on the population and infrastructure in the vicinity of the pipeline. A QRA requires the calculation of the frequency of failures and the consequences of failures. One of the main causes of failures in onshore pipelines is mechanical damage due to external interference, such as a dent, a gouge, or a dent and gouge. In the published literature, two methods have been used to calculate the probability of failure due to external interference: • historical failure data and • limit state functions combined with historical data (i.e. structural reliability-based methods). Structural reliability-based methods are mathematically complicated, compared to using historical failure data, but have several advantages, e.g. extrapolation beyond the limited historical data, and the identification of trends that may not be apparent in the historical data. In view of this complexity, proposed supplements to the UK pipeline design codes IGE/TD/1 (natural gas) and PD 8010 (all substances) — on the application of QRAs to proposed developments in the vicinity of major accident hazard pipelines — include simple ‘reduction factors’ for use in ‘screening’ risk assessments. These ‘reduction factors’ are based on a comprehensive parametric study using a structural reliability-based model to calculate the probability of failure due to mechanical damage, defined as: gouges, and dents and gouges. The two ‘reduction factors’ are expressed in terms of the design factor and wall thickness of the pipeline. It is shown that, through appropriate normalisation, the effects of diameter, grade and toughness are secondary. Reasonably accurate, but conservative, estimates of the probability of failure can be obtained using these ‘reduction factors’. The proposed methodology is considerably simpler than a structural reliability-based analysis. The development and verification of these ‘reduction factors’ is described in this paper.

Reliability analysis for critical reaction forces of lumber members with an end notch

1996 ◽  
Vol 23 (1) ◽  
pp. 202-210 ◽  
Author(s):  
Ian Smith ◽  
Ying Hei Chui ◽  
Lin Juan Hu
Keyword(s):  
Structural Reliability ◽  
Reaction Force ◽  
Service Condition ◽  
Design Criterion ◽  
Timber Species ◽  
Limit States ◽  
Beam Design ◽  
Design Variables ◽  
Property Data ◽  
Reaction Forces

The basis of new design provisions for avoidance of brittle failures in sawn lumber members with an end notch is explained. Linear elastic fracture mechanics and structural reliability concepts are combined with material property data to determine appropriate forms of equations for limiting the reaction force, when a notch is made on either the tension or compression face of a member. Following from this, the factored reaction force resistance of a member designed to the 1994 edition of the CSA Standard 086.1 "Engineering design in wood (limit states design)" depends upon the depth of the member and the geometry and size of an end notch if the notch is located on the tension face. A new property, the specified reaction force strength, which is a measure of the capability of the material to resist fracture, is taken to be independent of the timber species and stress grade of the lumber. Design variables such as duration of load and moisture service condition influence assignments of factored reaction force resistances for members end notched on the tension face. When a notch is located on the compression face of a member the resistance is simply the factored shear resistance of the residual cross section. As in previous editions of CSA Standard 086.1, notches are not permitted to have a depth greater than 0.25 times the depth of the section. Key words: lumber, fracture, structural reliability, notched beam, design criterion.

Developments in Structural Integrity Safety Cases for Highest Reliability Components in the UK

2016 ◽  
Author(s):  
T. Jelfs ◽  
M. Hayashi ◽  
A. Toft
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Structural Reliability ◽  
Structural Integrity ◽  
Lessons Learned ◽  
Advisory Group ◽  
Design Assessment ◽  
Safety Case ◽  
The Uk

Gross failure of certain components in nuclear power plant has the potential to lead to intolerable radiological consequences. For these components, UK regulatory expectations require that the probability of gross failure must be shown to be so low that it can be discounted, i.e. that it is incredible. For prospective vendors of nuclear power plant in the UK, with established designs, the demonstration of “incredibility of failure” can be an onerous requirement carrying a high burden of proof. Requesting parties may need to commit to supplementary manufacturing inspection, augmented material testing requirements, enhanced defect tolerance assessment, enhanced material specifications or even changes to design and manufacturing processes. A key part of this demonstration is the presentation of the structural integrity safety case argument. UK practice is to develop a safety case that incorporates the notion of ‘conceptual defence-in-depth’ to demonstrate the highest structural reliability. In support of recent Generic Design Assessment (GDA) submissions, significant experience has been gained in the development of so called “incredibility of failure” arguments. This paper presents an overview of some of the lessons learned relating to the identification of the highest reliability components, the development of the structural integrity safety arguments in the context of current GDA projects, and considers how the UK Technical Advisory Group on Structural Integrity (TAGSI) recommendations continue to be applied almost 15 years after their work was first published. The paper also reports the approach adopted by Horizon Nuclear Power and their partners to develop the structural integrity safety case in support of the GDA process to build the UK’s first commercial Boiling Water Reactor design.

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