Bond Shear Tests to Evaluate Different CFRP Shear Strengthening Strategies for I-Shaped Concrete Cross-Sections.

I-shaped concrete girders are widely used in precast bridge and roof construction, making them a common structural component in existing infrastructure. Despite well-established strengthening techniques using various innovative materials, such as externally bonded carbon fibre reinforced polymer (CFRP) reinforcement, the shear strengthening of an I-shaped concrete girder is not straightforward. Several research studies have shown that externally bonded CFRP reinforcement might exhibit early debonding at the concave corners of the I-shape, resulting in a marginal increase in shear capacity. This research study aims to assess the performance of two different CFRP shear strengthening strategies for I-shaped concrete cross-sections. In the first strategy, CFRP was bonded along the I-shape of the cross-section with the provision of additional anchorage. In the second strategy, the I-shape was transformed into a rectangular shape by using in-fill blocks over which the CFRP was bonded in a U-configuration. In addition to the strengthening strategies, the investigated parameters included two different materials for the in-fill blocks (conventional and aerated concrete) and two different anchoring schemes (bolted steel plate anchor and CFRP spike anchor). To avoid testing on large-scale girders, a new test methodology has been implemented on concrete I-sections. The test results demonstrate the feasibility of comparing different shear strengthening configurations dedicated to I-sections. Among other findings, the results showed that the local transformation of the I-shape to an equivalent rectangular shape could be a viable solution, resulting in shear strength enhancement of 12% to 53% without and with the anchorages, respectively.

An Automated Wireless System for Monitoring Concrete Structures Based on Embedded Electrical Resistivity Sensors: Data Transmission and Effects on Concrete Properties.

Modern infrastructure heavily relies on robust concrete structures, underscoring the critical need for effective monitoring to ensure their safety and durability. This paper addresses this imperative issue by introducing an innovative automated and wireless system for continuous structural monitoring. By employing embedded electrical resistivity sensors coupled with a wireless-based data transmission mechanism, real-time data collection becomes feasible. We provide a general description of the system's architecture and its application in a pilot study covering the effects of the devices on concrete properties and data transmission. The dielectric properties of concrete specimens were investigated under natural and accelerated curing/degradation and the results were used in the final design of the antenna device. Furthermore, a pilot test comprising four reinforced concrete columns was used to investigate the range of data transmission from inside to outside of the concrete, the effects of the hardware device on the compressive strength and concrete distribution in the columns, and the data transmission quality in real time under realistic exposure conditions.

Application of Cost Effective and Real-Time Resistivity Sensor to Study Early Age Concrete.

Concrete is a widely used construction material, demanding strict quality control to maintain its integrity. The durability and lifespan of concrete structures rely heavily, amongst other factors, on the characteristics of fresh and early age concrete, which are strongly dependent on the curing process. To ensure long-term durability, it is crucial to assess concrete properties throughout construction and verify compliance with design specifications. Currently, electrical resistivity-based sensors are available and used for quality control and monitoring, however, these sensors tend to be costly or only measure at a single location within the concrete cover. This study introduces a printed circuit board (PCB)-based array of electrodes capable of measuring concrete resistivity profiles across the concrete cover, from its fresh state to early age development. In this work, the feasibility of such resistivity PCB-sensors, novel for concrete, is evaluated under laboratory conditions. The sensors exhibit a promising performance in monitoring the efficiency of concrete curing under various conditions. Additionally, they successfully evaluate the effectiveness of internal curing (in our study, promoted by superabsorbent polymers) during the initial stages of hardening. This sensor array provides a valuable tool for monitoring the curing of concrete at early age, and showcases a preliminary solution that could be further developed to ensure long-term performance of concrete infrastructure.

Modeling the Prediction of the Session Rating of Perceived Exertion in Soccer: Unraveling the Puzzle of Predictive Indicators.

PURPOSE: To predict the session rating of perceived exertion (sRPE) in soccer and determine its main predictive indicators. METHODS: A total of 70 external-load indicators (ELIs), internal-load indicators, individual characteristics, and supplementary variables were used to build a predictive model. RESULTS: The analysis using gradient-boosting machines showed a mean absolute error of 0.67 (0.09) arbitrary units (AU) and a root-mean-square error of 0.93 (0.16) AU. ELIs were found to be the strongest predictors of the sRPE, accounting for 61.5% of the total normalized importance (NI), with total distance as the strongest predictor. The included internal-load indicators and individual characteristics accounted only for 1.0% and 4.5%, respectively, of the total NI. Predictive accuracy improved when including supplementary variables such as group-based sRPE predictions (10.5% of NI), individual deviation variables (5.8% of NI), and individual player markers (17.0% of NI). CONCLUSIONS: The results showed that the sRPE can be predicted quite accurately using only a relatively limited number of training observations. ELIs are the strongest predictors of the sRPE. However, it is useful to include a broad range of variables other than ELIs, because the accumulated importance of these variables accounts for a reasonable component of the total NI. Applications resulting from predictive modeling of the sRPE can help coaching staff plan, monitor, and evaluate both the external and internal training load.

The Use of Municipal Solid Waste Incineration Ash in Various Building Materials: A Belgian Point of View.

Huge amounts of waste are being generated, and even though the incineration process reduces the mass and volume of waste to a large extent, massive amounts of residues still remain. On average, out of 1.3 billion tons of municipal solid wastes generated per year, around 130 and 2.1 million tons are incinerated in the world and in Belgium, respectively. Around 400 kT of bottom ash residues are generated in Flanders, out of which only 102 kT are utilized here, and the rest is exported or landfilled due to non-conformity to environmental regulations. Landfilling makes the valuable resources in the residues unavailable and results in more primary raw materials being used, increasing mining and related hazards. Identifying and employing the right pre-treatment technique for the highest value application is the key to attaining a circular economy. We reviewed the present pre-treatment and utilization scenarios in Belgium, and the advancements in research around the world for realization of maximum utilization are reported in this paper. Uses of the material in the cement industry as a binder and cement raw meal replacement are identified as possible effective utilization options for large quantities of bottom ash. Pre-treatment techniques that could facilitate this use are also discussed. With all the research evidence available, there is now a need for combined efforts from incineration and the cement industry for technical and economic optimization of the process flow.

Differences in biological maturation, anthropometry and physical performance between playing positions in youth team handball.

It was the goal of this cross-sectional study to examine differences in maturity, anthropometry and physical performance between youth handball players across different playing positions (i.e. goalkeeper, back, pivot and wing). Multivariate analysis of covariance (MANCOVA), accounting for biological maturation, was used to assess positional differences in 472 male youth handball players from three age groups: U14, U15 and U16. Differences in age at peak height velocity were found in all age groups. Backs were significantly more mature than wings in U14 and U15 and than wings and pivots in U16. Furthermore, backs are overall taller, have a bigger arm span and perform best on tests for strength, agility and speed, especially in the U15 age group. Therefore, it can be concluded that youth players with the most advanced maturation status and the most favourable anthropometry and physical fitness scores, are consistently positioned in the back position. Players with a less advanced maturity status and an overall smaller stature are placed on the wing or pivot positions. In conclusion, it seems that anthropometrical and maturational characteristics are used by coaches to directly and/or indirectly select players for specific field positions. This strategy is risky since anthropometry and maturity status change over the years.

A longitudinal study of multidimensional performance characteristics related to physical capacities in youth handball.

Longitudinal research provides valuable information about change and progress towards elite performance. Unfortunately, there is a lack of longitudinal research in handball. In this study, 94 youth handball players (oldest group: n = 41; age 15-17 and youngest group: n = 53; age 13-15) were followed over a three-year period. Repeated measures ANCOVA was conducted to reveal longitudinal changes in anthropometry and physical performance between elite and non-elite players, controlling for maturation. Maturation effects were found for anthropometry (P < 0.01) and some physical performance measures in strength and speed (P < 0.05). The lack of significant interaction effects revealed that during the three years of the study the elite players did not improve their physical performance more rapidly than the non-elites. Furthermore, they had a similar anthropometric profile to the non-elites. Elite players performed better on the Yo-Yo Intermittent Recovery test (P < 0.01; on average 24.0 in the youngest group and 25.2% in the oldest group over the three years) and on the speed and coordination items (P < 0.05; shuttle run: 3.6 and 5.1%; cross hopping: 11.0 and 14.8%, handball-specific shuttle run: 7.6 and 7.7%; slalom dribble test: 10.7 and 8.9%; sprint 30 m: 4.9 and 3.9%). Additionally, Yo-Yo performance and coordination with and without a ball were the most discriminating factors between the playing levels. In conclusion, youth coaches and scouts within team handball should recognise the importance of good skills and an excellent endurance for talent identification purposes.

Relationship between sports participation and the level of motor coordination in childhood: a longitudinal approach.

OBJECTIVES: This study examined the stability of motor coordination and the relationship between motor coordination and organized sports participation over time. DESIGN: Longitudinal design. METHODS: A total of 371 children between six and nine years of age at initial testing completed a test battery measuring motor coordination in three consecutive years and a questionnaire on their club sports participation in year 1 and year 3 of testing. RESULTS: Correlation coefficients revealed the motor coordination of children to be a highly stable factor, ranging from 0.662 (6-8 years) to 0.873 (7-9 years). Results of the Repeated Measures ANOVA indicated that children who consistently practiced sports in a club environment over the three years of testing displayed better coordination levels than children who only partially participated or did not participate in a club environment at all. Moreover, stability was further indicated as consistent sports participation over time and changes or lack thereof did not substantially influence the development of motor coordination over time. In addition, the basic level of motor coordination and the amount of club sports participation significantly predicted sports participation two years later. CONCLUSION: The importance of the stability of motor coordination levels in childhood and its role in determining organized sports participation may have implications for talent identification purposes as well as potential health-related benefits in childhood and throughout the lifespan.

The relative age effect in a professional football club setting.

The relative age effect is an uneven distribution of birth date favouring subjects born in the initial months of a selection year. This study compared the birth-date distributions between several subgroups of Basque football players to identify whether the relative age effect is influenced by age and/or skill level. The study comprised 13,519 players including 114 senior professionals from the Spanish league's AC Bilbao over 21 seasons; over the season 2005-2006, it comprised elite youth (n=189) from the same club's academy; regional youth (n=4382) U11-U14 locally federated players; school youth (n=8834) U10-U11 locally registered school district players. Differences between the observed and expected birth-date distributions were tested based on data from the general Basque male population. Significant chi-square values were followed up by calculating odds ratios and 95% confidence intervals (CI) for the quartile and half-year distributions to examine subgroup differences in the relative age effect. Birth-date distributions of all groups of players showed a significant bias towards early birth in the selection year compared with the reference population (senior, chi-2(3) = 24.4, P < 0.001; elite youth, chi-2(3) = 59.1, P < 0.001; regional youth, chi-2(3) = 41.4, P < 0.001; school youth, chi-2(3) = 40.9, P < 0.001). Between-group comparison revealed that the relative age effect incidence progressively increased with a higher level of involvement in youth football. This bias represents a significant loss of potential youth football talent.

Anthropometric and performance measures for the development of a talent detection and identification model in youth handball.

The first part of this study examined in which basic morphological and fitness measures Under-14 (n=34) and Under-16 (n=47) male youth handball players differ from reference samples of the same age (n=430 and n=570, respectively). To help develop a talent identification model, the second part of the study investigated which specific morphological and performance measures describe differences between elite (n=18) and non-elite (n=29) Under-16 youth handball players. The results showed that Under-16 handball players were significantly taller than the reference group; this was not the case in the Under-14 age group. Physical fitness in handball players was significantly better than in the reference groups. Multivariate analysis of covariance (maturation and chronological age as covariates) showed that the Under-16 elite players were heavier and had greater muscle circumferences than their non-elite peers. Elite players scored significantly better on strength, speed and agility, and cardiorespiratory endurance but not on balance, upper limb speed, flexibility or upper body muscular endurance. Maturation was a significant covariate in anthropometric measures but not in physical performance. Discriminant analysis between elite and non-elite players revealed that height, running speed, and agility are important parameters for talent identification. Specific anthropometric measures, in addition to some performance measures, are useful for talent identification in youth handball.