Investigation of the Fatigue Stress of Orthotropic Steel Decks Based on an Arch Bridge with the Application of the Arlequin Method

Orthotropic steel decks are widely used in the construction of steel bridges. Although there are many fatigue-evaluation methods stipulated by codes, unexpected fatigue cracks are still detected in some bridges. To justify whether the local finite element model commonly used in fatigue investigations on orthotropic decks can correctly instruct engineering practices, the Arlequin framework is applied in this paper to determine the full fatigue stress under traffic loads. The convergence on and validity of this application for orthotropic decks are checked. Results show that the Arlequin model for deck-fatigue analysis established in this paper tends to be an efficient method for complete fatigue stress acquisition, whereby the vulnerable sites of orthotropic steel decks under traffic loads are defined. Vehicles near the flexible components, such as hangers or cables, can have adverse effects on the fatigue durability of decks. Additionally, the total number of vehicles and their arrangement concentration also affect fatigue performance. Complex traffic conditions cannot be fully loaded in local models. Regardless of the gross bridge mechanics and deck deformation, the fatigue stress range is underestimated by about 30–40%. Such a difference in fatigue assessment seems to explain the premature cracks observed in orthotropic steel decks.

Relationship between the Tensile Properties and Damping Capacity of Fe-22%Mn-12%Cr-4%Co-3%Ni-2%Si Alloys by Fatigue Stress

The relationship between the tensile properties and damping capacity of fatigue-damaged Fe-22%Mn-12%Cr-4%Co-3%Ni-2%Si alloy under various magnitudes of fatigue stress was investigated. Analytical results show that α′- and ε-martensite were formed due to fatigue stress. The formed α′- and ε-martensite followed a specific orientation and surface relief and intersected with each other. TEM observation and pattern analysis reveal that both α′- and ε-martensites formed on the austenite. As a result of X-ray diffraction, with an increase in fatigue stress, the volume fractions of α′- and ε-martensite were increased, and the increasing rate of the volume fraction of α′-martensite was higher than that of the ε-martensite. As the fatigue stress increased, the tensile strength and damping capacity increased, but the elongation decreased. Besides, as the strength increased and the elongation decreased, the damping capacity decreased. This result is inconsistent with the general tendency for metals but similar to that of alloys undergoing deformation-induced martensite transformation.

Internal training and match load quantification of one-match week schedules in female first league Portugal soccer team

La cuantificación de la carga de entrenamiento (TL) permite a los entrenadores gestionar la carga durante el entrenamiento con el objetivo de estar en la mejor forma física para la próxima competición. El propósito de este estudio fue comparar la Percepción Subjetiva de Esfuerzo (s-RPE) y el Índice Hooper (HI) entre deportes y partidos de un solo equipo de fútbol de la principal liga femenina portuguesa. En este estudio participaron dieciséis jugadores con una media ± DE edad, altura y peso de 24,0 ± 2,9 años, 164 ± 4,1 cm y 58,5 ± 8,2 kg, respectivamente. Los participantes completaron ≥80% de las sesiones de entrenamiento durante la temporada 2019/20. Los datos evaluados fueron s-RPE y HI, que midieron la calidad de la grasa, la fatiga, el estrés y el dolor muscular (DOMS). Los datos se analizaron en relación al número de días durante un microciclo competitivo (semana de juego), es decir, menos día de juego (MD-) con tres sesiones de entrenamiento por semana (MD-5; MD-4; MD-2). El estudio analizó datos para un total de 12 juegos y 45 sesiones de entrenamiento con ANOVA de medidas repetidas, p≤0,05. Los resultados mostraron diferencias entre MD-5 (85,2 ± 0,3min) vs MD-4 (87,2 ± 0,4min) vs MD-2 (80,6 ± 0.6min) vs MD (62,8 ± 4,9min), todos p <0,05; s-RPE mostró valores más altos en MD-5 (503,8 ± 19,0ua) vs MD-4 (473,2 ± 14,8ua) vs MD-2 (362,1 ± 12,1ua) vs MD (468, 2 ± 40,5ua); El HI mostró valores más altos en MD-5 (13,4 ± 0,5ua) frente a MD-4 (13,4 ± 0,4ua) frente a MD-2 (12,7 ± 0,5ua) frente a MD (11, 9 ± 0,4ua); DOMS reveló diferencias entre MD-4 vs MD-2 (3,1 ± 0,2 vs 2,7 ± 0,2ua), p<0,05. Se ha demostrado que existe una mayor carga de entrenamiento en el MD-5 y MD-4 en comparación con el MD-2. Los resultados de HI mostraron que la grasa, la fatiga, el estrés y DOMS estaban bien controlados por el equipo técnico y los jugadores. Training load (TL) quantification allow coaches to a better load management during training sessions to be in the best physical fitness to the next match. The aim of this study was to compare session rated of perceived exertion (s-RPE) and Hooper Index (HI) between training and match days from the same women’s Portuguese League team. Sixteen players with a mean±SD age, height and weight of 24.0±2.9 years, 164±4.1 cm and 58.5±8.2 kg, respectively, participated in this study. The participants completed ≥80% of the training sessions during 2019/20 in-season. Data was collected through the s-RPE and the HI that measured sleep quality, fatigue, stress, and muscle soreness (DOMS). Data was analysed in relation to the number of days away from the competitive one-match week (i.e., match day minus, MD-) with three training sessions a week (MD-5; MD-4; MD-2). The study analysed data from a total of 12 matches and 45 training sessions with repeated measures ANOVA, p≤0.05. Results showed differences between MD-5 (85.2±0.3min) vs MD-4 (87.2±0.4min) vs MD-2 (80.6±0.6min) vs MD (62.8±4.9min), all p<0.05; s-RPE showed higher values on MD-5 (503.8±19.0au) vs MD-4 (473.2±14.8au) vs MD-2 (362.1±12.1au) vs MD (468.2±40.5au); HI showed higher values on MD-5 (13.4±0.5au) vs MD-4 (13.4±0.4au) vs MD-2 (12.7±0.5au) vs MD (11.9±0.4au); DOMS revealed difference between MD-4 vs MD-2 (3.1±0.2 vs 2.7±0.2au), p<0.05. It was shown that there is a higher TL on MD-5 and MD-4 compared with MD-2. Results from HI showed that sleep, fatigue, stress and DOMS was well fair controlled by coaches and staff. A quantificação da carga de treino (CT) permite aos treinadores uma melhor gestão da carga dos jogadores durante as sessões de treino para que estejam na melhor condição física para o próximo jogo. O objetivo deste estudo foi comparar os valores da perceção subjetiva de esforço (s-RPE) e o Índice Hooper (HI) entre dias de treino e de jogo numa equipa feminina de Futebol da principal Liga feminina portuguesa. Participaram neste estudo dezasseis jogadoras com média ± DP de idade, altura e peso de 24,0 ± 2,9 anos, 164 ± 4,1 cm e 58,5 ± 8,2 kg, respetivamente. As participantes completaram ≥80% das sessões de treino durante a temporada de 2019/20. Os dados avaliados foram o s-RPE e o HI que mediu a qualidade do sono, fadiga, stresse e dor muscular (DOMS). Os dados foram recolhidos através do s-RPE e do IH que avaliaram a qualidade do sono, fadiga, stress e dor muscular (DOMS). Os dados foram analisados em relação ao número de dias para o jogo competitivo (ou seja, dia de jogo menos, MD-) com três sessões de treino por semana (MD-5; MD-4; MD-2). O estudo analisou 12 jogos e 45 sessões de treino através de medidas repetidas ANOVA, p≤0,05. Os resultados mostraram diferenças entre MD-5 (85,2±0,3min) vs MD-4 (87,2±0,4min) vs MD-2 (80,6±0,6min) vs MD (62,8±4,9min), todos p<0,05; s-RPE mostrou valores mais altos em MD-5 (503,8±19,0au) vs MD-4 (473,2±14,8au) vs MD-2 (362,1±12,1au) vs MD (468,2±40,5au); HI mostrou valores mais altos em MD-5 (13,4±0,5au) vs MD-4 (13,4±0,4au) vs MD-2 (12,7±0,5au) vs MD (11,9±0,4au); DOMS revelou diferença entre MD-4 vs MD-2 (3,1±0,2 vs 2,7±0,2au), p<0,05. Foi demonstrado que existe uma maior CT no MD-5 e MD-4 em comparação com o MD-2. Os resultados do HI mostraram que o sono, fadiga, stress e DOMS foi bem controlado pelos treinadores e staff.

Decreased Sleep and Subjective Well-Being as Independent Predictors of Injury in Female Collegiate Volleyball Players

Background: The relationship among sleep duration, subjective well-being, and injury risk in athletes is poorly defined. Purpose: To evaluate the independent effects of sleep duration, sleep quality, and subjective well-being on in-season injuries in collegiate female volleyball athletes. Study Design: Cohort study; Level of evidence, 2. Methods: During a 9-month competitive season, 17 female National Collegiate Athletic Association (NCAA) Division I volleyball players reported mood, fatigue, stress, soreness, sleep duration (hours), and sleep quality every morning. Well-being measures were recorded from 0 (worst) to 5 (best), and all time-loss injuries were recorded by the team athletic trainer. Separate mixed-effects logistic regression models were used to evaluate the effects of sleep and subjective well-being on in-season injury. Each well-being variable was also included in a separate mixed-effects logistic regression model with sleep duration as a covariate. Results: A total of 54 injuries were recorded during the study period. Compared with days without an injury, mood, fatigue, stress, soreness, sleep quality, and sleep duration were significantly worse the day before an injury occurred. In the separate prediction models, in-season injury was significantly predicted by fatigue (odds ratio [OR], 0.56 [95% CI, 0.36-0.86]; P = .008), mood (OR, 0.52 [95% CI, 0.35-0.78]; P = .002), stress (OR, 0.63 [95% CI, 0.42-0.94]; P = .023), soreness (OR, 0.54 [95% CI, 0.38-0.79]; P = .001), sleep quality (OR, 0.49 [95% CI, 0.34-0.7]; P < .001), and sleep duration (OR, 0.69 [95% CI, 0.55-0.87]; P = .001). In the multivariable models, sleep duration remained a significant independent predictor in each of the subsequent multivariable models (OR, 0.72-0.74; P < .05 for all), as did mood (OR, 0.55 [95% CI, 0.36-0.83); P = .005) and soreness (OR, 0.57 [95% CI, 0.39-0.83]; P = .003), while fatigue (OR, 0.65 [95% CI, 0.42-1]; P = .054) and stress (OR, 0.68 [95% CI, 0.45-1]; P = .061) no longer reached statistical significance. Conclusion: Increased sleep duration, mood, and decreased soreness were independently associated with a reduced risk of in-season injury in this cohort of female NCAA volleyball players.

Applicability Of The Ooda Loop Theory For Analysis Of Human Error Processes In The Maritime Safety

The publication evaluates the applicability of John Boyd’s OODA Loop (observe-orient-decide-act) theory for the analysis of human error in the maritime industry. The predominant share of human error among the range of maritime safety issues is revealed. The interdependence between the different phases of the OODA Loop to achieve the desired state of maritime safety is studied, namely the correct actions in each of the implemented cycles. So, the paramount importance of situational awareness as a prerequisite for safety is proven. The mechanisms for manifestation of other factors endangering maritime safety are also analyzed, such as: lack of competence, fatigue, stress, etc. In conclusion, the role of the time factor in the realization of the OODA Loop is assessed and in this context, approaches are offered to increase the possibility for realization of a quality loop.

Coffee in the Workplace: A Social Break or a Performance Enhancer?

Coffee is a socially rooted drink with pharmacological properties. It is embedded in different everyday rituals, including ‘coffee breaks’ during working hours. This paper analyzes the role of coffee at workplace. Focusing on three professional areas associated with high pressure and responsive demands, we explore the social expression of coffee use at work, and how it is mobilized as a tool for managing sleepiness, fatigue, stress, and concentration problems, amongst other work-related issues.