scholarly journals Reliability Assessment of Steel-Concrete Composite Beams considering Metal Corrosion Effects

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Trong-Ha Nguyen ◽  
Duy-Duan Nguyen
Keyword(s):  
Structural Reliability ◽  
Global Sensitivity Analysis ◽  
Metal Corrosion ◽  
Sensitivity Analyses ◽  
Cross Sectional ◽  
First Order ◽  
Industrial Structures ◽  
Input Parameters ◽  
Sobol’S Method ◽  
Input Variables

Steel-concrete composite (SCC) beams have been widely used in civil engineering and industrial structures. This kind of structure has some advantages such as fast fabrication time and optimized weight. However, designers are often concerned about the initial reliability, while over time the structural reliability will be reduced, especially due to metal corrosion. The objective of the paper is to assess the structural reliability of corroded SCC beams, in which the input parameters are considered as random variables. The SCC beam has been designed according to Eurocode-4 (EC-4), in which input parameters consist of cross-sectional dimensions of the beam, material properties, and applied loads. The effects of the random input variables on the reliability of structures are evaluated by sensitivity analyses, which are calculated by the global sensitivity analysis using Sobol’s method and Monte Carlo simulation. The developed reliability analysis algorithm in this study is verified with previous studies, highlighting the capability of the used method. Four different corrosion levels, which are pristine, 10-year, 20-year, and 50-year, are considered in the sensitivity analyses of the SCC beam. Finally, a series of first-order and total-order Sobol’s indices are obtained for measuring the sensitivity of input parameters with four corrosion levels.

scholarly journals New Importance Measures Based on Failure Probability in Global Sensitivity Analysis of Reliability

Mathematics ◽  
2021 ◽  
Vol 9 (19) ◽  
pp. 2425
Author(s):  
Zdeněk Kala
Keyword(s):  
Sensitivity Analysis ◽  
Global Sensitivity Analysis ◽  
Binary Outcome ◽  
Global Sensitivity ◽  
First Order ◽  
Sensitivity Measure ◽  
Sensitivity Indices ◽  
Alternative Measures ◽  
Input Variables ◽  
Dome Shape

This article presents new sensitivity measures in reliability-oriented global sensitivity analysis. The obtained results show that the contrast and the newly proposed sensitivity measures (entropy and two others) effectively describe the influence of input random variables on the probability of failure Pf. The contrast sensitivity measure builds on Sobol, using the variance of the binary outcome as either a success (0) or a failure (1). In Bernoulli distribution, variance Pf(1 − Pf) and discrete entropy—Pfln(Pf) − (1 − Pf)ln(1 − Pf) are similar to dome functions. By replacing the variance with discrete entropy, a new alternative sensitivity measure is obtained, and then two additional new alternative measures are derived. It is shown that the desired property of all the measures is a dome shape; the rise is not important. Although the decomposition of sensitivity indices with alternative measures is not proven, the case studies suggest a rationale structure of all the indices in the sensitivity analysis of small Pf. The sensitivity ranking of input variables based on the total indices is approximately the same, but the proportions of the first-order and the higher-order indices are very different. Discrete entropy gives significantly higher proportions of first-order sensitivity indices than the other sensitivity measures, presenting entropy as an interesting new sensitivity measure of engineering reliability.

scholarly journals Global Sensitivity Analysis Of In-Plane Elastic Buckling Of Steel Arches

2020 ◽  
Vol 10 (6) ◽  
pp. 6476-6480
Author(s):  
Τ. Η. Nguyen
Keyword(s):  
Sensitivity Analysis ◽  
Monte Carlo Simulation ◽  
Material Properties ◽  
Global Sensitivity Analysis ◽  
Elastic Buckling ◽  
Random Input ◽  
Uniform Compression ◽  
Global Sensitivity ◽  
Industrial Structures ◽  
Input Variables

Steel arches are widely used in civil engineering and industrial structures. Their response depends on material properties, geometric dimensions, and boundary conditions. The objective of the current study is to perform global sensitivity analysis and to assess the influence of random input parameters on the in-plane elastic buckling of steel arches. The in-plane elastic buckling load of steel arches under uniform compression proposed in previous studies is adopted. The influence of the random input variables of the structure is evaluated using Sobol’s global sensitivity analysis. Monte Carlo simulation is also employed to rank the influence of input random variables.

A Primer on the Assessment of Economic Impacts of Leisure Events

2020 ◽  
Vol 24 (1) ◽  
pp. 47-56
Author(s):  
Ove Oklevik ◽  
Grzegorz Kwiatkowski ◽  
Mona Kristin Nytun ◽  
Helene Maristuen
Keyword(s):  
Impact Assessment ◽  
Economic Impact ◽  
Study Design ◽  
Impact Analysis ◽  
Sensitivity Analyses ◽  
Primary Data ◽  
Music Festival ◽  
Economic Impact Analysis ◽  
Economic Impact Assessment ◽  
Input Variables

The quality of any economic impact assessment largely depends on the adequacy of the input variables and chosen assumptions. This article presents a direct economic impact assessment of a music festival hosted in Norway and sensitivity analyses of two study design assumptions: estimated number of attendees and chosen definition (size) of the affected area. Empirically, the article draws on a state-of-the-art framework of an economic impact analysis and uses primary data from 471 event attendees. The results show that, first, an economic impact analysis is a complex task that requires high precision in assessing different monetary flows entering and leaving the host region, and second, the study design assumptions exert a tremendous influence on the final estimation. Accordingly, the study offers a fertile agenda for local destination marketing organizers and event managers on how to conduct reliable economic impact assessments and explains which elements of such analyses are particularly important for final estimations.

scholarly journals Examination of Construct Validity and Criterion-Related Validity of the German Motor Test in Egyptian Schoolchildren

2021 ◽  
Vol 18 (16) ◽  
pp. 8341
Author(s):  
Osama Abdelkarim ◽  
Julian Fritsch ◽  
Darko Jekauc ◽  
Klaus Bös
Keyword(s):  
Construct Validity ◽  
Physical Fitness ◽  
Large Scale ◽  
Body Height ◽  
Cross Sectional Study ◽  
Latent Factors ◽  
Cross Sectional ◽  
First Order ◽  
Motor Test ◽  
Health Related

Physical fitness is an indicator for children’s public health status. Therefore, the aim of this study was to examine the construct validity and the criterion-related validity of the German motor test (GMT) in Egyptian schoolchildren. A cross-sectional study was conducted with a total of 931 children aged 6 to 11 years (age: 9.1 ± 1.7 years) with 484 (52%) males and 447 (48%) females in grades one to five in Assiut city. The children’s physical fitness data were collected using GMT. GMT is designed to measure five health-related physical fitness components including speed, strength, coordination, endurance, and flexibility of children aged 6 to 18 years. The anthropometric data were collected based on three indicators: body height, body weight, and BMI. A confirmatory factor analysis was conducted with IBM SPSS AMOS 26.0 using full-information maximum likelihood. The results indicated an adequate fit (χ2 = 112.3, df = 20; p < 0.01; CFI = 0.956; RMSEA = 0.07). The χ2-statistic showed significant results, and the values for CFI and RMSEA showed a good fit. All loadings of the manifest variables on the first-order latent factors as well as loadings of the first-order latent factors on the second-order superordinate factor were significant. The results also showed strong construct validity in the components of conditioning abilities and moderate construct validity in the components of coordinative abilities. GMT proved to be a valid method and could be widely used on large-scale studies for health-related fitness monitoring in the Egyptian population.

scholarly journals A Novel Global Sensitivity Measure Based on Probability Weighted Moments

Symmetry ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 90
Author(s):  
Shufang Song ◽  
Lu Wang
Keyword(s):  
Sensitivity Analysis ◽  
Global Sensitivity Analysis ◽  
Small Samples ◽  
Double Loop ◽  
Numerical Estimation ◽  
Global Sensitivity ◽  
Sensitivity Measure ◽  
Probability Weighted Moments ◽  
Input Variables ◽  
Single Set

Global sensitivity analysis (GSA) is a useful tool to evaluate the influence of input variables in the whole distribution range. Variance-based methods and moment-independent methods are widely studied and popular GSA techniques despite their several shortcomings. Since probability weighted moments (PWMs) include more information than classical moments and can be accurately estimated from small samples, a novel global sensitivity measure based on PWMs is proposed. Then, two methods are introduced to estimate the proposed measure, i.e., double-loop-repeated-set numerical estimation and double-loop-single-set numerical estimation. Several numerical and engineering examples are used to show its advantages.

scholarly journals Knowledge of blood donation and associated factors in Ethiopia: a systematic review and meta-analysis

BMJ Open ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. e044343
Author(s):  
Addisu Getie ◽  
Adam Wondmieneh ◽  
Melaku Bimerew ◽  
Getnet Gedefaw ◽  
Asmamaw Demis
Keyword(s):  
Systematic Review ◽  
Associated Factors ◽  
Blood Donation ◽  
Meta Analysis ◽  
Educational Status ◽  
Sensitivity Analyses ◽  
Cross Sectional ◽  
Level Of Knowledge ◽  
Cross Sectional Studies ◽  
Study Participants

ObjectiveTo assess the level of knowledge about blood donation and associated factors in Ethiopia.DesignSystematic review and meta-analysis.MethodsBoth published and unpublished cross-sectional studies on the level of knowledge about blood donation in Ethiopia were included. Articles from different databases such as PubMed/MEDLINE, HINARI, EMBASE, Scopus, Google Scholar and African Journals Online were searched. Cochrane I2 statistics were used to check for heterogeneity. Subgroup and sensitivity analyses of evidence of heterogeneity were carried out. Egger’s test with funnel plot was conducted to investigate publication bias.ResultTwenty cross-sectional studies with a total of 8338 study participants (4712 men and 3626 women) were included. The overall nationwide level of knowledge about blood donation was 56.57% (95% CI 50.30 to 62.84). Being in secondary school and above (adjusted OR=3.12; 95% CI 2.34 to 4.16) and being male (adjusted OR=1.81; 95% CI 1.44 to 2.28) were the factors associated with level of knowledge about blood donation.ConclusionMore than half of the study participants were knowledgeable about blood donation. Sex and educational status were the factors significantly associated with level of knowledge about blood donation in Ethiopia. Therefore, there is a need for education and dissemination of information about blood donation among the general population to build adequate knowledge and maintain regular blood supply.

scholarly journals Association of Varus Thrust With Pain and Stiffness and Activities of Daily Living in Patients With Medial Knee Osteoarthritis

2016 ◽  
Vol 96 (2) ◽  
pp. 167-175 ◽  
Author(s):  
Naoto Fukutani ◽  
Hirotaka Iijima ◽  
Takahiko Fukumoto ◽  
Daisuke Uritani ◽  
Eishi Kaneda ◽  
...  
Keyword(s):  
Knee Osteoarthritis ◽  
Activities Of Daily Living ◽  
Daily Living ◽  
Predictor Variable ◽  
Cross Sectional Study ◽  
Sensitivity Analyses ◽  
Varus Alignment ◽  
Cross Sectional ◽  
Medial Knee ◽  
Knee Oa

Background Increasing evidence highlights potential associations between varus thrust and health domains associated with knee osteoarthritis (OA). Objective The aim of this study was to investigate the association between varus thrust and 2 subcategories—“pain and stiffness” and “activities of daily living (ADL)”—of the Japanese Knee Osteoarthritis Measure (JKOM). Design This was a cross-sectional study. Methods In total, 296 outpatients with knee OA visiting orthopedic clinics were enrolled. The inclusion criteria were age ≥50 years, medial knee OA and Kellgren-Lawrence (K/L) grade ≥1 in one or both knees, and the ability to walk independently. Standard posterior-anterior knee radiographs were measured for varus alignment. Participants were video recorded while walking and were evaluated for the presence or absence of varus thrust. Pain and stiffness of the knee joint and ADL were evaluated using the JKOM. Multivariate regressions (outcomes: pain and stiffness and ADL; predictor variable: varus thrust) were performed. Results Varus thrust was present in 46 (16.2%) of 284 patients. Multivariate regression analyses demonstrated that varus thrust is independently associated with pain and stiffness, adjusted for age, sex, body mass index, K/L grade, and varus alignment (β=.17, P=.005). However, the association between varus thrust and ADL was not significant (β=.11, P=.058). Based on sensitivity analyses, including participants of K/L grade 1 had little influence on this analysis. Limitations Only 16.2% of participants had a varus thrust. Moreover, a cause-effect relationship between varus thrust and pain and stiffness remains unknown due to the cross-sectional design of this study. Conclusions Varus thrust was associated with pain and stiffness in patients with medial knee OA. However, the association between varus thrust and ADL did not reach significance.

An Efficient Response Surface Method Using Givens Transformation for Structural Reliability Analysis

2012 ◽  
Vol 532-533 ◽  
pp. 408-411
Author(s):  
Wei Tao Zhao ◽  
Yi Yang ◽  
Tian Jun Yu
Keyword(s):  
Response Surface ◽  
Response Surface Method ◽  
Structural Reliability ◽  
Limit State ◽  
State Function ◽  
Limit State Function ◽  
Surface Method ◽  
Mathematical Techniques ◽  
Input Variables ◽  
Improved Accuracy

The response surface method was proposed as a collection of statistical and mathematical techniques that are useful for modeling and analyzing a system which is influenced by several input variables. This method gives an explicit approximation of the implicit limit state function of the structure through a number of deterministic structural analyses. However, the position of the experimental points is very important to improve the accuracy of the evaluation of failure probability. In the paper, the experimental points are obtained by using Givens transformation in such way these experimental points nearly close to limit state function. A Numerical example is presented to demonstrate the improved accuracy and computational efficiency of the proposed method compared to the classical response surface method. As seen from the result of the example, the proposed method leads to a better approximation of the limit state function over a large region of the design space, and the number of experimental points using the proposed method is less than that of classical response surface method.

Radial lift on a suspended finite-sized sphere due to fluid inertia for low-Reynolds-number flow through a cylinder

2013 ◽  
Vol 722 ◽  
pp. 159-186 ◽  
Author(s):  
Sukalyan Bhattacharya ◽  
Dil K. Gurung ◽  
Shahin Navardi
Keyword(s):  
Reynolds Number ◽  
Particle Diameter ◽  
Axial Direction ◽  
Perturbation Scheme ◽  
Fluid Inertia ◽  
Regular Perturbation ◽  
Cross Sectional ◽  
First Order ◽  
Reynolds Number Flow ◽  
Freely Suspended

AbstractThis article describes the radial drift of a suspended sphere in a cylinder-bound Poiseuille flow where the Reynolds number is small but finite. Unlike past studies, it considers a circular narrow conduit whose cross-sectional diameter is only $1. 5$–$6$ times the particle diameter. Thus, the analysis quantifies the effect of fluid inertia on the radial motion of the particle in the channel when the flow field is significantly influenced by the presence of the suspended body. To this end, the hydrodynamic fields are expanded as a series in Reynolds number, and a set of hierarchical equations for different orders of the expansion is derived. Accordingly, the zeroth-order fields in Reynolds number satisfy the Stokes equation, which is accurately solved in the presence of the spherical particle and the cylindrical conduit. Then, recognizing that in narrow vessels Stokesian scattered fields from the sphere decrease exponentially in the axial direction, a simpler regular perturbation scheme is used to quantify the first-order inertial correction to hydrodynamic quantities. Consequently, it is possible to obtain two results. First, the sphere is assumed to follow the axial motion of a freely suspended sphere in a Stokesian condition, and the radial lift force on it due to the presence of fluid inertia is evaluated. Then, the approximate motion is determined for a freely suspended body on which net hydrodynamic force including first-order inertial lift is zero. The results agree well with the available experimental results. Thus, this study along with the measured data would precisely describe particle dynamics inside narrow tubes.

scholarly journals Modeling the Costs of Hospital-Acquired Infections in New Zealand

2003 ◽  
Vol 24 (3) ◽  
pp. 214-223 ◽  
Author(s):  
Nicholas Graves ◽  
Tanya M. Nicholls ◽  
Arthur J. Morris
Keyword(s):  
New Zealand ◽  
Economic Cost ◽  
Cost Effective ◽  
Sensitivity Analyses ◽  
Primary Data ◽  
Health Board ◽  
District Health ◽  
Hospital Acquired Infections ◽  
Input Variables ◽  
Hospital Acquired

AbstractObjective:To model the economic costs of hospital-acquired infections (HAIs) in New Zealand, by type of HAI.Design:Monte Carlo simulation model.Setting:Auckland District Health Board Hospitals (DHBH), the largest publicly funded hospital group in New Zealand supplying secondary and tertiary services. Costs are also estimated for predicted HAIs in admissions to all hospitals in New Zealand.Patients:All adults admitted to general medical and general surgical services.Method:Data on the number of cases of HAI were combined with data on the estimated prolongation of hospital stay due to HAI to produce an estimate of the number of bed days attributable to HAI. A cost per bed day value was applied to provide an estimate of the economic cost. Costs were estimated for predicted infections of the urinary tract, surgical wounds, the lower and upper respiratory tracts, the bloodstream, and other sites, and for cases of multiple sites of infection. Sensitivity analyses were undertaken for input variables.Results:The estimated costs of predicted HAIs in medical and surgical admissions to Auckland DHBH were $10.12 (US $4.56) million and $8.64 (US $3.90) million, respectively. They were $51.35 (US $23.16) million and $85.26 (US $38.47) million, respectively, for medical and surgical admissions to all hospitals in New Zealand.Conclusions:The method used produces results that are less precise than those of a specifically designed study using primary data collection, but has been applied at a lower cost. The estimated cost of HAIs is substantial, but only a proportion of infections can be avoided. Further work is required to identify the most cost-effective strategies for the prevention of HAI.

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