Search results for "strength"

Increasing the flexural capacity of RC beams using steel angles and pre-tensioned stainless steel ribbons

2016

This article presents an experimental programme on reinforced concrete beams retrofitted with steel angles and pre-stressed stainless steel ribbons to increase their flexural strength and ductility. Two different configurations of the steel ribbon were designed, and two companion specimens for each type considered were subjected to a four-point bending test to facilitate a direct comparison in the analysis of the effectiveness of the retrofitting technique. The influence of longitudinal steel angles and transverse stainless steel ribbons is analysed, and the concrete confinement due to stainless steel ribbons examined. The strengthened beams show remarkable increments in flexural strength a…

Validation of a Shear Model for RC and Hybrid Beams with Two Different Inclinations of Transversal Reinforcement

2016

The validation of an analytical model recently proposed for evaluation of the shear capacity in Reinforced Concrete (RC) beams containing multiple inclination of transverse stirrups is presented. The model is a suitable extension of that currently proposed in Eurocode 2 for the evaluation of the shear resistance, and it is derived by means of the the variable-inclination stressfield theory based on Nielsen’s plastic approach. Experimental and numerical data available in the literature on Hybrid Steel-Trussed Concrete Beams (HSTCBs) are used for model validation and result discussion. Finally, also the comparison with a different analytical approach for the assessment of the shear resistance…

Dynamics of hydrofracturing and permeability evolution in layered reservoirs

2015

International audience; A coupled hydro-mechanical model is presented to model fluid driven fracturing in layered porous rocks. In the model the solid elastic continuum is described by a discrete element approach coupled with a fluid continuum grid that is used to solve Darcy based pressure diffusion. The model assumes poro-elasto-plastic effects and yields real time dynamic aspects of the fracturing and effective stress evolution under the influence of excess fluid pressure gradients. We show that the formation and propagation of hydrofractures are sensitive to mechanical and tectonic conditions of the system. In cases where elevated fluid pressure is the sole driving agent in a stable tec…

Assessing physical capacity, disability, and health-related quality of life in neck pain

2010

Study of the Strengths and Weaknesses of Nursing Work Environments in Primary Care in Spain

2021

Background: Nursing work environments are defined as the characteristics of the workplace that promote or hinder the provision of professional care by nurses. Positive work environments lead to better health outcomes. Our study aims to identify the strengths and weaknesses of primary health care settings in Spain. Methods: Cross-sectional study carried out from 2018 to 2019. We used the Practice Environment Scale of the Nursing Work Index and the TOP10 Questionnaire of Assessment of Environments in Primary Health Care for data collection. The associations between sociodemographic and professional variables were analyzed. Results: In total, 702 primary care nurses participated in the study. …

Age and Muscle Function Are More Closely Associated With Intracellular Magnesium, as Assessed by

2019

Total serum magnesium is a common clinical measurement for assessing magnesium status; however, magnesium in blood represents less than 1% of the body’s total magnesium content. We measured intramuscular ionized magnesium by phosphorus magnetic resonance spectroscopy (31P-MRS) and tested the hypothesis that this measure better correlates with skeletal muscle function and captures more closely the effect of aging than the traditional measure of total serum magnesium. Data were collected from 441 participants (age 24–98 years) in the Baltimore Longitudinal Study of Aging (BLSA), a study of normative aging that encompasses a broad age range. Results showed that intramuscular ionized magnesium …

Velocity-based resistance training: do women need greater velocity loss to maximize adaptations?

2021

Abstract Purpose Men and women typically display different neuromuscular characteristics, force–velocity relationships, and differing strength deficit (upper vs. lower body). Thus, it is not clear how previous recommendations for training with velocity-loss resistance training based on data in men will apply to women. This study examined the inter-sex differences in neuromuscular adaptations using 20% and 40% velocity-loss protocols in back squat and bench press exercises. Methods The present study employed an 8-week intervention (2 × week) comparing 20% vs. 40% velocity-loss resistance training in the back squat and bench press exercises in young men and women (~ 26 years). Maximum strengt…

A 10-Week Block of Combined High-Intensity Endurance and Strength Training Produced Similar Changes in Dynamic Strength, Body Composition, and Serum …

2020

Purpose: To examine the potential sex differences in adaptations to combined endurance and strength training in recreationally endurance trained (eumenorrheic) women (n = 9) and men (n = 10). Methods: Isometric (ISOMmax) and dynamic bilateral leg press (1RM), countermovement jump (CMJ), running performance (3,000 m time trial), lean mass and body fat % (LEAN and FAT% determined by dual X-ray absorptiometry) as well as serum testosterone and cortisol (TES and COR, respectively, measured using hormone-specific immunoassay kits) were examined before a control period and pre, mid, and post a supervised 10-week combined high-intensity interval endurance training (4 × 4 min intervals and 3 × 3 × …

Fluctuations in muscle strength, shooting accuracy and serum hormone concentrations in conscripts during a 3-week combat training period

2015

Conscripts and soldiers have to perform their duties in a multistressor environment. During prolonged periods of combat training, fluctuations in strength levels and hormone concentrations have been noted. However, there is limited information regarding the changes in shooting performance and whether changes in strength and hormonal concentrations are correlated with it. This study examined strength levels, shooting performance and hormonal fluctuations during a 3-week combat training period. Possible correlations between the variables were examined and investigated. This study lasted for 37 days and involved 49 Finnish male conscripts as subjects. The subjects acted as their own controls d…

Study of the Stability of Citrate Capped AgNPs in Several Environmental Water Matrices by Asymmetrical Flow Field Flow Fractionation

2021

Asymmetrical flow field-flow fractionation (AF4) coupled to UV-Vis and dynamic light scattering (DLS) detectors in series, was tested for stability studies of dispersions of citrate-capped silver nanoparticles (AgNPs) in several water matrices. The main goal is to provide knowledge to understand their possible behavior in the environment for short times since mixturing (up to 180 min). Ultrapure (UPW), bottled (BW1, BW2), tap (TW), transitional (TrW) and sea water (SW) matrices were assayed. Observations were compatible with the aggregation of AgNPs, a change in the plasmon band and a size growth with time were done. Fractograms showed different evolution fingerprints in the function of the…