Structural Safety Assessment of Pontoon-Type VLFS Considering Damage of Breakwater

2002 ◽  
Author(s):  
Masahiko Fujikubo ◽  
Tao-Yun Xiao ◽  
Kazuhiro Yamamura
Keyword(s):  
Failure Probability ◽  
Safety Assessment ◽  
Structural Reliability ◽  
Structural Safety ◽  
Extreme Waves ◽  
Floating Structure ◽  
Safety Level ◽  
Transverse Waves ◽  
Collapse Mode ◽  
Planar Shape

Structural reliability analysis of a pontoon-type Very Large Floating Structure (VLFS) of rectangular planar shape surrounded by gravity-type breakwater in extreme waves is performed considering the damage of breakwater. Bending and shear collapses are considered for floating structure, while overturning damage for breakwater. The ultimate bending and shear strengths of the floating structure are calculated using Idealized Structural Unit Method (ISUM) and FEM. The calculated failure probability of floating structure is compared with the specified target safety level. It has been found that the considered floating structure is most likely to fail in the bending collapse mode in transverse waves and that the corresponding failure probability satisfies the target level.

scholarly journals Structural Safety Assessment of Marine Operations From a Long-Term Perspective: A Case Study of Offshore Wind Turbine Blade Installation

2019 ◽  
Author(s):  
Amrit Shankar Verma ◽  
Zhen Gao ◽  
Zhiyu Jiang ◽  
Zhengru Ren ◽  
Nils Petter Vedvik
Keyword(s):  
Failure Probability ◽  
Safety Assessment ◽  
Routine Activity ◽  
Structural Safety ◽  
Offshore Wind Turbine ◽  
Structural Failure ◽  
Blade Root ◽  
Extreme Response

Abstract A marine operation is a complex non-routine activity of limited duration carried out in offshore environment. Due to safety reasons, these operations are normally performed within specific sea state limits, which are derived from numerical modelling and analysis of hazardous events. In view of the uncertainties in the assessment of structural responses under stochastic environmental conditions, these limiting curves correspond to a target structural failure probability recommended in offshore standards (for example, 10−4 per operation as specified by DNV-GL). However, one of the main limitations is that these curves do not reflect site-specific safety assessment. The current paper presents a novel methodology for assessing the structural safety level of marine operations from a long-term perspective. The methodology includes estimation of extreme response distribution under all possible operational sea states (i.e. the operational domain under the limiting sea states) for a given offshore site and is compared to the response limit to obtain an average failure probability. A case study is also presented for a blade root mating process onto preassembled hub using a jack-up crane vessel and risk of impact between root and hub is considered critical. Global time-domain simulations are performed using multibody dynamics, and extreme value distributions for impact velocities are derived for different wind-wave conditions. The allowable impact velocity between the blade root and the hub is determined by an explicit finite element analysis of the damage at the blade root. Finally, the average failure probabilities considering the operational domain are obtained for four different European offshore sites and are compared to the target level of structural failure probability considered for the limiting sea states.

scholarly journals Evaluation of the Level of Safety and Disaster Preparedness of Comprehensive Healthcare Centers in Babol, Iran

2019 ◽  
pp. 287-293
Keyword(s):  
Disaster Preparedness ◽  
Safety Assessment ◽  
Healthcare Services ◽  
Cross Sectional Study ◽  
Descriptive Statistics ◽  
Structural Safety ◽  
Average Score ◽  
Sectional Study ◽  
Safety Level ◽  
Cross Sectional

INTRODUCTION: Comprehensive healthcare centers should be able to provide primary healthcare services during disasters; therefore, it is necessary to assess their safety and preparedness to ensure that they can have acceptable functionality in critical situations. In this regard, the present study aimed to evaluate the level of safety and disaster preparedness of comprehensive healthcare centers in Babol, Iran. METHODS: The present descriptive cross-sectional study was conducted in 2016 to investigate the safety level and disaster preparedness of 232 comprehensive healthcare centers in Babol, using observation and checklists. The used checklist consisted of three parts, namely functional, structural, and non-structural safety assessment. Finally, the collected data were analyzed using descriptive statistics. FINDINGS: Based on the data analysis, the studied centers were more prone to weather hazards than other types of disasters. Moreover, the evaluation of the different aspects of the functionality of the centers showed that the best functionality was observed in firefighting, provision of the environmental health services, organization and structure, and provision of infectious disease management services, in that order. The non-structural safety obtained the highest average score (37.49) while the scores of functional and structural safety were 21.76 and 9.27, respectively. CONCLUSION: Based on the results, all the studied comprehensive healthcare centers had a moderate level of structure and functional safety, while no center had a completely desirable level. Therefore, it is recommended to develop proper plans and monitor the comprehensive healthcare centers to eliminate their defects and improve the level of their safety.

scholarly journals Selected Aspects of Failure Probability Assessment for Fire Situation / Wybrane Problemy Szacowania Prawdopodobienstwa Zawodu W Sytuacji Pozaru

2011 ◽  
Vol 57 (3) ◽  
pp. 297-311
Author(s):  
M. Maslak
Keyword(s):  
Failure Probability ◽  
Structural Safety ◽  
Probability Assessment ◽  
Safety Factors ◽  
Safety Level ◽  
The People ◽  
Global Condition ◽  
Partial Safety Factors ◽  
The Moment ◽  
Bearing Structure

Abstract To reliably calibrate suitable partial safety factors, useful for the specification of global condition describing structural safety level in considered design case, usually the evaluation of adequate failure probability is necessary. In accidental fire situation, not only probability of the collapse of load-bearing structure, but also another probability related to the people staying in a building at the moment of fire occurence should be assessed. Those values are different one from another in qualitative sense but they are coupled because they are determined by similar factors. The first one is the conditional probability with the condition that fire has already occured, whereas the second is the probability of failure in case of a potential fire, which can take place in the examined building compartment, but its ignition has not yet appeared. An engineering approach to estimate such both probabilities is presented and widely discussed in the article.

Value of information of in situ inspections of mooring lines

2021 ◽  
pp. 1748006X2098740
Author(s):  
Jorge Mendoza ◽  
Jacopo Paglia ◽  
Jo Eidsvik ◽  
Jochen Köhler
Keyword(s):  
Pitting Corrosion ◽  
Value Of Information ◽  
Structural Reliability ◽  
Structural Safety ◽  
Statistical Dependence ◽  
Mooring System ◽  
Mooring Lines ◽  
Corrosion Condition ◽  
Chain Links

Mooring systems that are used to secure position keeping of floating offshore oil and gas facilities are subject to deterioration processes, such as pitting corrosion and fatigue crack growth. Past investigations show that pitting corrosion has a significant effect on reducing the fatigue resistance of mooring chain links. In situ inspections are essential to monitor the development of the corrosion condition of the components of mooring systems and ensure sufficient structural safety. Unfortunately, offshore inspection campaigns require large financial commitments. As a consequence, inspecting all structural components is unfeasible. This article proposes to use value of information analysis to rank identified inspection alternatives. A Bayesian Network is proposed to model the statistical dependence of the corrosion deterioration among chain links at different locations of the mooring system. This is used to efficiently update the estimation of the corrosion condition of the complete mooring system given evidence from local observations and to reassess the structural reliability of the system. A case study is presented to illustrate the application of the framework.

scholarly journals Development and Validation of a Post-Earthquake Safety Assessment System for High-Rise Buildings Using Acceleration Measurements

Mathematics ◽  
2021 ◽  
Vol 9 (15) ◽  
pp. 1758
Author(s):  
Koji Tsuchimoto ◽  
Yasutaka Narazaki ◽  
Billie F. Spencer
Keyword(s):  
Safety Assessment ◽  
Large Scale ◽  
Model Updating ◽  
Safety Evaluation ◽  
Assessment System ◽  
Shaking Table ◽  
Structural Safety ◽  
High Rise ◽  
Steel Building ◽  
Earthquake Safety

After a major seismic event, structural safety inspections by qualified experts are required prior to reoccupying a building and resuming operation. Such manual inspections are generally performed by teams of two or more experts and are time consuming, labor intensive, subjective in nature, and potentially put the lives of the inspectors in danger. The authors reported previously on the system for a rapid post-earthquake safety assessment of buildings using sparse acceleration data. The proposed framework was demonstrated using simulation of a five-story steel building modeled with three-dimensional nonlinear analysis subjected to historical earthquakes. The results confirmed the potential of the proposed approach for rapid safety evaluation of buildings after seismic events. However, experimental validation on large-scale structures is required prior to field implementation. Moreover, an extension to the assessment of high-rise buildings, such as those commonly used for residences and offices in modern cities, is needed. To this end, a 1/3-scale 18-story experimental steel building tested on the shaking table at E-Defense in Japan is considered. The importance of online model updating of the linear building model used to calculate the Damage Sensitive Features (DSFs) during the operation is also discussed. Experimental results confirm the efficacy of the proposed approach for rapid post-earthquake safety evaluation for high-rise buildings. Finally, a cost-benefit analysis with respect to the number of sensors used is presented.

Structural Safety Assessment of a 1100 TEU Container Ship, Based on a Enhanced Long Term Fatigue Analysis

2014 ◽  
Vol 1036 ◽  
pp. 935-940
Author(s):  
Leonard Domnisoru ◽  
Ionica Rubanenco ◽  
Mihaela Amoraritei
Keyword(s):  
Safety Assessment ◽  
Safety Evaluation ◽  
Irregular Waves ◽  
Structural Safety ◽  
Random Wave ◽  
Wave Loads ◽  
Strength Assessment ◽  
Integrated Method ◽  
Hydroelastic Response

This paper is focused on an enhanced integrated method for structural safety assessment of maritime ships under extreme random wave loads. In this study is considered an 1100 TEU container test ship, with speed range 0 to 18 knots. The most comprehensive criteria for ships structural safety evaluation over the whole exploitation life is based on the long term ship structures analysis, that includes: stress hot-spots evaluation by 3D/1D-FEM hull models, computation of short term ship dynamic response induced by irregular waves, long term fatigue structure assessment. The analysis is enhanced by taking into account the ships speed influence on hydroelastic response. The study includes a comparative analysis on two scenarios for the correlation between the ships speed and waves intensity. The standard constant ship speed scenario and CENTEC scenario, with total speed loss at extreme waves condition, are considered. Instead of 20 years ship exploitation life estimated by classification societies rules from the long term structural safety criteria, the enhanced method has predicted more restrictive values of 14.4-15.7 years. The numerical analyses are based on own software and user subroutines. The study made possible to have a more realistic approach of ships structural strength assessment, for elastic and faster ships as container carriers, in compare to the standard one based only on naval rules, delivering a method with higher confidence in the designed structural safety.

scholarly journals Structural safety assessment for FLNG-LNGC system during offloading operation scenario

2017 ◽  
Vol 31 (2) ◽  
pp. 192-201 ◽  
Author(s):  
Zhi-qiang Hu ◽  
Dong-wei Zhang ◽  
Dong-ya Zhao ◽  
Gang Chen
Keyword(s):  
Safety Assessment ◽  
Structural Safety

Structural safety and design under climate change

2019 ◽  
Author(s):  
Pietro Croce ◽  
Paolo Formichi ◽  
Filippo Landi
Keyword(s):  
Climate Change ◽  
Greenhouse Gas ◽  
Structural Reliability ◽  
Greenhouse Gas Emission ◽  
Extreme Value ◽  
Structural Safety ◽  
Climate Projections ◽  
Climate Conditions ◽  
Impact Of Climate Change ◽  
The Impact

<p>The impact of climate change on climatic actions could significantly affect, in the mid-term future, the design of new structures as well as the reliability of existing ones designed in accordance to the provisions of present and past codes. Indeed, current climatic loads are defined under the assumption of stationary climate conditions but climate is not stationary and the current accelerated rate of changes imposes to consider its effects.</p><p>Increase of greenhouse gas emissions generally induces a global increase of the average temperature, but at local scale, the consequences of this phenomenon could be much more complex and even apparently not coherent with the global trend of main climatic parameters, like for example, temperature, rainfalls, snowfalls and wind velocity.</p><p>In the paper, a general methodology is presented, aiming to evaluate the impact of climate change on structural design, as the result of variations of characteristic values of the most relevant climatic actions over time. The proposed procedure is based on the analysis of an ensemble of climate projections provided according a medium and a high greenhouse gas emission scenario. Factor of change for extreme value distribution’s parameters and return values are thus estimated in subsequent time windows providing guidance for adaptation of the current definition of structural loads.</p><p>The methodology is illustrated together with the outcomes obtained for snow, wind and thermal actions in Italy. Finally, starting from the estimated changes in extreme value parameters, the influence on the long-term structural reliability can be investigated comparing the resulting time dependent reliability with the reference reliability levels adopted in modern Structural codes.</p>

Causes of Structural Failures with Steel Structures

2017 ◽  
Author(s):  
Goran Alpsten
Keyword(s):  
Structural Damage ◽  
Human Error ◽  
Structural Reliability ◽  
Steel Structures ◽  
Fatigue Loading ◽  
Structural Instability ◽  
Human Errors ◽  
Collapse Mode ◽  
Load Carrying ◽  
Structural Failures

This paper is based on the experience from investigating over 400 structural collapses, incidents and serious structural damage cases with steel structures which have occurred over the past four centuries. The cause of the failures is most often a gross human error rather than a combination of “normal” variations in parameters affecting the load-carrying capacity, as considered in normal design procedures and structural reliability analyses. Human errors in execution are more prevalent as cause for the failures than errors in the design process, and the construction phase appears particularly prone to human errors. For normal steel structures with quasi-static (non-fatigue) loading, various structural instability phenomena have been observed to be the main collapse mode. An important observation is that welds are not as critical a cause of structural steel failures for statically loaded steel structures as implicitly understood in current regulations and rules for design and execution criteria.

Sign in / Sign up

Export Citation Format

Share Document