Search results for "strengthening"
showing 9 items of 59 documents
Strain gradient plasticity, strengthening effects and plastic limit analysis
2010
Abstract Within the framework of isotropic strain gradient plasticity, a rate-independent constitutive model exhibiting size dependent hardening is formulated and discussed with particular concern to its strengthening behavior. The latter is modelled as a (fictitious) isotropic hardening featured by a potential which is a positively degree-one homogeneous function of the effective plastic strain and its gradient. This potential leads to a strengthening law in which the strengthening stress, i.e. the increase of the plastically undeformed material initial yield stress, is related to the effective plastic strain through a second order PDE and related higher order boundary conditions. The plas…
Inflammation status of healthy young men : initial and specific responses to resistance training
2018
Our primary aim was to study the effects of a 4-week preparatory resistance-training (RT) period followed by 12 weeks of 2 specific RT protocols (either hypertrophic-strength (HS) or strength-hypertrophy-power training) on inflammation markers and the possible relationship of the changes in abdominal fat and lean mass to the changes in inflammation status. A total of 82 healthy men were included in the study. Maximal concentric leg press strength (1-repetition maximum), total body lean mass, total body and abdominal fat mass, circulating high-sensitivity C-reactive protein, interleukin-6, interleukin-1 receptor antagonist (IL-1ra), monocyte chemoattractant protein 1 (MCP-1), and selected ad…
Shakedown analysis for a class of strengthening materials within the framework of gradient plasticity
2010
Abstract The classical shakedown theory is extended to a class of perfectly plastic materials with strengthening effects (Hall–Petch effects). To this aim, a strain gradient plasticity model previously advanced by Polizzotto (2010) is used, whereby a featuring strengthening law provides the strengthening stress, i.e. the increase of the yield strength produced by plastic deformation, as a degree-zero homogeneous second-order differential form in the accumulated plastic strain with associated higher order boundary conditions. The extended static (Melan) and kinematic (Koiter) shakedown theorems are proved together with the related lower bound and upper bound theorems. The shakedown limit loa…
Flexural behaviour of calcarenite masonry walls reinforced with FRP sheets
2015
The use of fiber-reinforced polymers (FRP) for structural strengthening has become increasingly popular in recent years. Several applications of FRP have been proposed and applied, depending on the target of the technique, kind and/or material of the structural member. In particular, because of their great tensile strength, FRP materials are commonly used to enhance the out-of-plane behaviour of masonry walls, allowing to increase their strength, ductility and improving safety against overturning. For these reasons, FRP laminates are often applied in vulnerable ancient buildings in seismic areas to reinforce façades and walls with poor structural features. However, some issues arise when ad…
EFFECTIVENESS OF BASALT FIBRE-REINFORCED CEMENTITIOUS SYSTEMS IN CONFINING MASONRY MEMBERS: AN EXPERIMENTAL INVESTIGATION
2020
The use of composites based on fibre-reinforced polymers (FRPs) to strengthen masonry columns has become a common practice in the last decades. FRPs, however, exhibit some shortcomings when applied to masonry substrates, due to the organic nature of their matrix. For this reason, increasing attention is paid today to composites based on fibre-reinforced cementitious matrices (FRCMs), in which the polymeric matrix is replaced with an inorganic matrix (such as cementitious mortars). Cementitious matrices guarantee higher breathability and compatibility with the substrate, less sensitivity to debonding at the interfaces, and higher resistance to fire and high temperatures. Moreover, due to the…
Analysis of Compliance with Time under Tension and Force during Strengthening Exercises with Elastic Bands
2021
Quantifying training variables of a physical exercise modality is essential for an appropriate dosage. In training with elastic bands, time under tension (TUT) and force represent the duration and intensity of this force-training modality. The aims of this study were to evaluate the degree of compliance to TUT prescription for three different scenarios of two exercises and the comparison of the force values obtained versus the estimate values. A total of 29 healthy volunteers were evaluated in a clinical environment under controlled conditions in 3 different scenarios (different velocities or ROMs) of both shoulder abduction and knee extension in 2 sets of 10 repetitions per scenario within…
The Prevalence of Urinary Incontinence among Adolescent Female Athletes: A Systematic Review
2021
This review aimed to synthesize the most up-to-date evidence regarding the prevalence of urinary incontinence (UI) among adolescent female athletes. We conducted a systematic review of studies regarding UI in female athletes less than 19 years of age. This review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRIMSA). The electronic databases of PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), Scopus, and Web of Science (WOS) were searched between October and November 2020. After blinded peer evaluation, a total of 215 studies were identified and nine were included. Risk of bias was assessed using the Strengt…
Numerical modelling of bond behaviour in Fabric Reinforced Cementitious Matrix strengthened reinforced concrete members
2022
Fabric Reinforced Cementitious Matrix (FRCM) composites are widely seen as offering advantages in structural retrofitting of existing buildings. In spite of their reputed effectiveness, FRCM systems typically suffers from several drawbacks related to the mechanical characterization due to complex stress transfer mechanicisms that can develop at fiber-matrix and FRCM-substrate interface. Numerous experimental studies focus on this topic, but few numerical studies are addressed to better understand the variables involved in the problem. This paper aims to propose a simple 1D numerical model to predict the shear bond behaviour of FRCM applied on concrete substrate, providing support to deduce …
Vecākā pirmsskolas vecuma bērnu stājas nostiprināšana sporta nodarbībās
2018
Bakalaura darba tēma. Vecākā pirmsskolas vecuma bērnu stājas nostiprināšana sporta nodarbībās. Bakalaura darba autors. Anda Priedoliņa. Bakalaura darba mērķis. Teorētiski analizēt un praktiski pētīt vecākā pirmsskolas vecuma bērnu stājas sekmēšanas iespējas sporta nodarbībās. Bakalaura darba uzdevumi: 1.Analizēt pedagoģijas un psiholoģijas zinātnieku atziņas par stāju un vecākā pirmsskolas vecuma bērnu attīstību. 2.Izzināt sporta nodarbību struktūru, saturu un stājas nostiprināšanas iespējas tajās. 3.Pētīt stājas sekmēšanas iespējas sporta nodarbībās vecākā pirmsskolas vecuma bērniem. Bakalaura darba saturs. Darbs sastāv no 2 daļām –teorētiskās un empīriskās. Teorētiskā daļā tika analizēta …