Committee V.1: Accidental Limit States

Concern for accidental scenarios for ships and offshore structures and for their structural components leading to limit states. Types of accidental scenarios shall include collision, grounding, dropped objects, explosion, and fire. Attention shall be given to hazard identification, accidental loads and nonlinear structural consequences including strength reduction, affecting the probability of failure and related risks. Uncertainties in the use of accidental scenarios for design and analysis shall be highlighted. Consideration shall be given to the practical application of methods and to the development of ISSC guidance for quantitative assessment and management of accidental risks

The ISSC 2022 committee III.1-Ultimate strength benchmark study on the ultimate limit state analysis of a stiffened plate structure subjected to uniaxial compressive loads

This paper presents a benchmark study on the ultimate limit state analysis of a stiffened plate structure subjected to uniaxial compressive loads, initiated and coordinated by the ISSC 2022 technical committee III.1-Ultimate Strength. The overall objective of the benchmark is to establish predictions of the buckling collapse and ultimate strength of stiffened plate structures subjected to compressive loads. Participants were asked to perform ultimate strength predictions for a full-scale reference experiment on a stiffened steel plate structure utilizing any combination of class rules, guidelines, numerical approaches and simulation procedures as they saw fit. The benchmark study was carried out blind and divided into three phases. In the first phase, only descriptions of the experimental setup, the geometry of the reference structure, and the nominal material specifications were distributed. In the second phase, the actual properties of the reference structure were included. In the third and final phase, all available information on the reference structure and measured properties were distributed, including the material properties and laser-scanned geometry. This paper presents the results obtained from seventeen submitted FE simulations as well as details on the experiment. It also presents comparisons of the force versus the displacement curve, failure modes and locations for each phase, among others, and a discussion on the participants’ ability to predict the characteristics of the reference experiment with the information that is available for the phase. The outcome of the study is a discussion and recommendations regarding the design of finite element models for the ultimate state analysis of stiffened plate structures, with emphasis on the prediction of the ultimate capacity, force-displacement curve, and failure mode and location related to access to data, uncertainties and modeling of the material properties, geometric imperfections and distortions, and residual stresses

Exercise in vivo marks human myotubes in vitro: Training-induced increase in lipid metabolism.

BACKGROUND AND AIMS:Physical activity has preventive as well as therapeutic benefits for overweight subjects. In this study we aimed to examine effects of in vivo exercise on in vitro metabolic adaptations by studying energy metabolism in cultured myotubes isolated from biopsies taken before and after 12 weeks of extensive endurance and strength training, from healthy sedentary normal weight and overweight men. METHODS:Healthy sedentary men, aged 40-62 years, with normal weight (body mass index (BMI) < 25 kg/m2) or overweight (BMI ≥ 25 kg/m2) were included. Fatty acid and glucose metabolism were studied in myotubes using [14C]oleic acid and [14C]glucose, respectively. Gene and protein expressions, as well as DNA methylation were measured for selected genes. RESULTS:The 12-week training intervention improved endurance, strength and insulin sensitivity in vivo, and reduced the participants' body weight. Biopsy-derived cultured human myotubes after exercise showed increased total cellular oleic acid uptake (30%), oxidation (46%) and lipid accumulation (34%), as well as increased fractional glucose oxidation (14%) compared to cultures established prior to exercise. Most of these exercise-induced increases were significant in the overweight group, whereas the normal weight group showed no change in oleic acid or glucose metabolism. CONCLUSIONS:12 weeks of combined endurance and strength training promoted increased lipid and glucose metabolism in biopsy-derived cultured human myotubes, showing that training in vivo are able to induce changes in human myotubes that are discernible in vitro

Effects of 12 weeks of exercise on myotube glucose metabolism.

<p>Satellite cells isolated from biopsies from <i>m</i>. <i>vastus lateralis</i> before and after 12 weeks of exercise were cultured and differentiated to myotubes. Oxidation and cell-associated (CA) radioactivity of [¹⁴C]glucose were measured, and total cellular uptake (CO₂+CA), oxidation (CO₂), and fractional oxidation () were determined. <b>(A)</b> Glucose oxidation and total cellular uptake presented as nmol/mg protein. Values are presented as means ± SEM for all participants combined (n = 18). <b>(B)</b> Fractional glucose oxidation. Values are presented as means ± SEM for all participants combined (n = 18). <b>(C)</b> Glucose metabolism relative to before exercise. Values are presented as means ± SEM for all participants combined (n = 18). *Statistically significant vs. before exercise (<i>p</i> < 0.05, linear mixed-model analysis, SPSS). <b>(D)</b> Glucose oxidation and total cellular uptake presented as nmol/mg protein in study group when separated by BMI. Values are presented as means ± SEM (n = 7 in the normal weight group and n = 11 in the overweight group). <b>(E)</b> Fractional glucose oxidation in absolute values in study group when separated by BMI. Values are presented as means ± SEM (n = 7 in the normal weight group and n = 11 in the overweight group). <b>(F)</b> Glucose metabolism relative to before exercise in study group when separated by BMI. Values are presented as means ± SEM (n = 7 in the normal weight group and n = 11 in the overweight group). *Statistically significant vs. before exercise (<i>p</i> < 0.05, linear mixed-model analysis, SPSS). ^$Statistically significant vs. normal weight group (<i>p</i> < 0.05, linear mixed-model analysis, SPSS). <b>(G)</b> Pearson’s test of correlation between exercise-induced changes in leg press and glucose oxidation in myotubes. Δ = after exercise–before exercise. Full line represents the regression line for all donors (n = 18, Pearson’s correlation coefficient, r = 0.52, and <i>p</i> = 0.03), whereas stapled line represents the regression line for the overweight group (n = 11, Pearson’s correlation coefficient, r = 0.68, and <i>p</i> = 0.02).</p

Effects of 12 weeks of exercise on myotube expression of lipid metabolism associated genes.

<p>Satellite cells isolated from biopsies from <i>m</i>. <i>vastus lateralis</i> before and after 12 weeks of exercise were cultured and differentiated to myotubes. mRNA was isolated and expression assessed by qPCR. <b>(A)</b> mRNA expression after exercise relative to before exercise for all participants combined. All values were corrected for the housekeeping control <i>GAPDH</i>, and presented as means ± SEM (n = 18). <b>(B)</b> mRNA expression after exercise relative to before exercise for study group when separated by BMI. All values were corrected for the housekeeping control <i>GAPDH</i>, and presented as means ± SEM (n = 7 in the normal weight group and n = 11 in the overweight group).</p

List of materials and respective producers.

<p>List of materials and respective producers.</p