Colonnes en béton armé renforcées de PRFV sous un chargement sismique simulé

Abstract : Steel and fiber-reinforced-polymer (FRP) materials have different mechanical and physical characteristics. High corrosion resistance, high strength to weight ratio, non-conductivity, favorable fatigue enable the FRP to be considered as alternative reinforcement for structures in harsh environment. Meanwhile, FRP bars have low modulus of elasticity and linear-elastic stress-strain curve. These features raise concerns about the applicability of using such materials as reinforcement for structures prone to earthquakes. The main demand for the structural members in structures subjected to seismic loads is dissipating energy without strength loss which is known as ductility. In the rigid frames, columns are expected to be the primary elements of energy dissipation in structures subjected to seismic loads. The present study addresses the feasibility of reinforced-concrete columns totally reinforced with glass-fiber-reinforced-polymer (GFRP) bars achieving reasonable strength and the drift requirements specified in various codes. Eleven full-scale reinforced concrete columns—two reinforced with steel bars (as reference specimens) and nine totally reinforced with GFRP bars—were constructed and tested to failure. The columns were tested under quasi-static reversed cyclic lateral loading and simultaneously subjected to compression axial load. The columns are 400 mm square cross-section with a shear span 1650 mm. The specimen simulates a column with 3.7 m in height in a typical building with the point of contra-flexure located at the column mid-height. The tested parameters were the longitudinal reinforcement ratio (0.63, 0.95 and 2.14), the spacing of the transverse stirrups (80, 100, 150), tie configuration (C1, C2, C3 and C4), and axial load level (20%, 30% and 40%). The test results clearly show that properly designed and detailed GFRP-reinforced concrete columns could reach high deformation levels with no strength degradation. An acceptable level of energy dissipation compared with steel-reinforced concrete columns is provided by GFRP reinforced concrete columns. The dissipated energy of GFRP reinforced concrete columns was 75% and 70% of the counter steel columns at 2.5% and 4% drift ratio respectively. High drift capacity achieved by the columns up to 10% with no significant loss in strength. The high drift capacity and acceptable dissipated energy enable the GFRP columns to be part of the moment resisting frames in regions prone to seismic activities. The experimental ultimate drift ratios were compared with the estimated drift ratios using the confinement Equation in CSA S806-12. It was found from the comparison that the confinement Equation underestimates values of the drift ratios thus the experimental drift ratios were used to modify transverse FRP reinforcement area in CSA S806-12. The hysteretic behavior encouraged to propose a design procedure for the columns to be part of the moderate ductile and ductile moment resisting frames. The development of design guidelines, however, depends on determining the elastic and inelastic deformations and on assessing the force modification factor and equivalent plastic-hinge length for GFRP-reinforced concrete columns. The experimental results of the GFRP-reinforced columns were used to justify the design guideline, proving the accuracy of the proposed design equations.L’acier et les matériaux à base de polymères renforcés de fibres (PRF) ont des caractéristiques physiques et mécaniques différentes. La résistance à la haute corrosion, le rapport résistance vs poids, la non-conductivité et la bonne résistance à la fatigue font des barres d’armature en PRF, un renforcement alternatif aux barres d’armature en acier, pour des structures dans des environnements agressifs. Cependant, les barres d’armature en PRF ont un bas module d’élasticité et une courbe contrainte-déformation sous forme linéaire. Ces caractéristiques soulèvent des problèmes d'applicabilité quant à l’utilisation de tels matériaux comme renforcement pour des structures situées en forte zone sismique. La principale exigence pour les éléments structuraux des structures soumises à des charges sismiques est la dissipation d'énergie sans perte de résistance connue sous le nom de ductilité. Dans les structures rigides de type cadre, on s'attend à ce que les colonnes soient les premiers éléments à dissiper l'énergie dans les structures soumises à ces charges. La présente étude traite de la faisabilité des colonnes en béton armé entièrement renforcées de barres d’armature en polymères renforcés de fibres de verre (PRFV), obtenant une résistance et un déplacement latéral raisonnable par rapport aux exigences spécifiées dans divers codes. Onze colonnes à grande échelle ont été fabriquées: deux colonnes renforcées de barres d'acier (comme spécimens de référence) et neuf colonnes renforcées entièrement de barres en PRFV. Les colonnes ont été testées jusqu’à la rupture sous une charge quasi-statique latérale cyclique inversée et soumises simultanément à une charge axiale de compression. Les colonnes ont une section carrée de 400 mm avec une portée de cisaillement de 1650 mm pour simuler une colonne de 3,7 m de hauteur dans un bâtiment typique avec le point d’inflexion situé à la mi-hauteur. Les paramètres testés sont : le taux d’armature longitudinal (0,63%, 0,95% et 2,14 %), l'espacement des étriers (80mm, 100mm, 150 mm), les différentes configurations (C1, C2, C3 et C4) et le niveau de charge axiale (20%, 30 % et 40%). Les résultats des essais montrent clairement que les colonnes en béton renforcées de PRFV et bien conçues peuvent atteindre des niveaux de déformation élevés sans réduction de résistance. Un niveau acceptable de dissipation d'énergie, par rapport aux colonnes en béton armé avec de l’armature en acier, est atteint par les colonnes en béton armé de PRFV. L'énergie dissipée des colonnes en béton armé de PRFV était respectivement de 75% et 70% des colonnes en acier à un rapport déplacement latéral de 2,5% et 4%. Un déplacement supérieur a été atteint par les colonnes en PRFV jusqu'à 10% sans perte significative de résistance. La capacité d’un déplacement supérieur et l’énergie dissipée acceptable permettent aux colonnes en PRFV de participer au moment résistant dans des régions sujettes à des activités sismiques. Les rapports des déplacements expérimentaux ultimes ont été comparés avec les rapports estimés en utilisant l’Équation de confinement du code CSA S806-12. À partir de la comparaison, il a été trouvé que l’Équation de confinement sous-estime les valeurs des rapports de déplacement, donc les rapports de déplacement expérimentaux étaient utilisés pour modifier la zone de renforcement transversal du code CSA S806-12. Le comportement hystérétique encourage à proposer une procédure de conception pour que les colonnes fassent partie des cadres rigides à ductilité modérée et résistant au moment. Cependant, l'élaboration de guides de conception dépend de la détermination des déformations élastiques et inélastiques et de l'évaluation du facteur de modification de la force sismique et de la longueur de la rotule plastique pour les colonnes en béton armé renforcées de PRFV. Les résultats expérimentaux des colonnes renforcées de PRFV étudiées ont été utilisés pour justifier la ligne directrice de conception, ce qui prouve l’efficacité des équations de conception proposées

Treatment Of A Patient With Thoracolumbar Scoliosis Utilizing A Regional Interdependence Approach Including Components Of The Schroth Method: A Case Report

Background and Purpose: Spinal deformity is a challenging spinal disorder in adults. A scoliotic curve of \u3e10 degrees exists in up to 12% of the population and while surgery is the definitive measure, there is limited evidence to guide non-surgical treatment. This case investigated traditional physical therapy (PT) treatment utilizing a Regional Interdependence Approach (RIA) and components of the Schroth method for a patient with chronic low back pain (CLBP). Case Description: A 66 year old male presented with CLBP, worst upon rising in the AM with (6/10 NPRS). Imaging demonstrated thoracolumbar dextroscoliosis, bilateral foraminal narrowing and associated spondylolisthesis of the fifth lumbar vertebrae. A RIA exam revealed mobility deficits of thoracolumbar spine, instability of L5-S1, and a 1.38” leg length discrepancy. A comprehensive treatment approach was used including lumbar stabilization exercises and postural therapy, including components of the Schroth method. Outcomes: Following 12 weeks, pain improved from 6/10 to 4/105, with the patient reporting no pain when arising from bed. 30-second sit to stand improved from five to eight. Following implementation of a shoe lift visible changes were noted in pelvic symmetry. However, the degree of scoliosis appeared unchanged and no subjective improvements were noted on the Roland-Morris Low Back Pain Questionnaire (RMLBPQ)

Druggable cavities and allosteric modulators of the cell division cycle 7 (CDC7) kinase

Cell division cycle 7 kinase (CDC7) has been found overexpressed in many cancer cell lines being also one of the kinases involved in the nuclear protein TDP-43 phosphorylation in vivo. Thus, inhibitors of CDC7 are emerging drug candidates for the treatment of oncological and neurodegenerative unmet diseases. All the known CDC7 inhibitors are ATP-competitives, lacking of selectivity enough for success in clinical trials. As allosteric sites are less conserved among kinase proteins, discovery of allosteric modulators of CDC7 is a great challenge and opportunity in this field. Using different computational approaches, we have here identified new druggable cavities on the human CDC7 structure and subsequently selective CDC7 inhibitors with allosteric modulation mainly targeting the pockets where the interaction between this kinase and its activator DBF4 takes place.</p

Epidemiology of Acute Gastroenteritis Outbreaks Caused by Human Calicivirus (Norovirus and Sapovirus) in Catalonia: A Two Year Prospective Study, 2010-2011

<div><p>Background</p><p>The epidemiology of cases of acute gastroenteritis (AGE) of viral etiology is a relevant public health issue. Due to underreporting, the study of outbreaks is an accepted approach to investigate their epidemiology. The objective of this study was to investigate the epidemiological characteristics of AGE outbreaks due to norovirus (NoV) and sapovirus (SV) in Catalonia.</p><p>Material and Methods</p><p>Prospective study of AGE outbreaks of possible viral etiology notified during two years in Catalonia. NoV and SV were detected by real time reverse transcription polymerase (RT-PCR).</p><p>Results</p><p>A total of 101 outbreaks were registered affecting a total of 2756 persons and 12 hospitalizations (hospitalization rate: 0.8x1,000,000 persons-year); 49.5% of outbreaks were foodborne, 45.5% person to person and 5% waterborne. The distribution of outbreaks according to the setting showed a predominance of catering services (39.6%), nursing homes and long term care facilities (26.8%) and schools (11.9%). The median number of cases per outbreak was 17 (range 2–191). The total Incidence rate (IR) was 18.3 per 100,000 persons-years (95%CI: 17.6–19.0). The highest IR was in persons aged ≥65 years (43.6x100,000 (95% CI: 41.0–46.2)) (p<0.001). A total of 1065 samples were analyzed with a positivity rate of 60.8%. 98% of positive samples were NoV (GII 56.3%; GI 4.2%; GII+GI 4.2%; non- typable 33.0%). SV was identified in two person-to-person transmission outbreaks in children.</p><p>Conclusions</p><p>These results confirm the relevance of viral AGE outbreaks, both foodborne and person-to-person, especially in institutionalized persons. SV should be taken into account when investigating viral AGE outbreaks.</p></div

Distribution of acute gastroenteritis outbreaks by month of occurrence and transmission mode.

<p>Catalonia 2010 and 2011.* Cold months (November to April) significantly higher incidence than warm months (May to October) for both transmission modes (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0152503#pone.0152503.t003" target="_blank">Table 3</a>).</p

Incidence rates and risk ratio of infection, hospitalization rates, medical consultation and absenteeism according to age groups and gender.

<p>Catalonia 2010–2011.</p

Distribution of percentage of outbreaks by season of the year and transmission mode.

<p>Catalonia 2010–2011.</p

Distribution of outbreaks according to setting of occurrence and mode transmission.

<p>Catalonia 2010–2011.</p

Crosstalk between Phosphodiesterase 7 and Glycogen Synthase Kinase-3: Two Relevant Therapeutic Targets for Neurological Disorders

Chronic neuroinflammation has been increasingly recognized as a primary mechanism underlying acute brain injury and neurodegenerative diseases. Enhanced expression of diverse pro-inflammatory agents in glial cells has been shown to contribute to the cell death that takes place in these disorders. Previous data from our group have shown that different inhibitors of the cyclic adenosine monophosphate (cAMP) specific phosphodiesterase 7 (PDE7) and glycogen synthase kinase-3 (GSK-3) enzymes are potent anti-inflammatory agents in different models of brain injury. In this study, we investigated cross-talk between PDE7 and GSK-3, two relevant therapeutic targets for neurological disorders, using a chemical approach. To this end, we compared specific inhibitors of GSK-3 and PDE7 with dual inhibitors of both enzymes with regard to anti-inflammatory effects in primary cultures of glial cells treated with lipopolysaccharide. Our results show that the GSK-3 inhibitors act exclusively by inhibition of this enzyme. By contrast, PDE7 inhibitors exert their effects via inhibition of PDE7 to increase intracellular cAMP levels but also through indirect inhibition of GSK-3. Activation of protein kinase A by cAMP results in phosphorylation of Ser9 of GSK-3 and subsequent inhibition. Our results indicate that the indirect inhibition of GSK-3 by PDE7 inhibitors is an important mechanism that should be considered in the future development of pharmacological treatments

Effect of S14 on <i>in vivo</i> inflammation and rotational behavior.

<p>Lipopolysaccharide (LPS, 10 µg) or vehicle was injected unilaterally into the adult <i>substantia nigra pars compacta</i> (SNpc) of adult rats. A group of animals also received S14 (20 nmol) or BRL50481 (BRL, 60 nmol) together with LPS. (<b>A</b>) After 72 h the brains were removed and tissue sections were processed for CD11b (OX-42) immunoreactivity lo label activated microglia. Scale bars, 500 µm. Insets scale bars, 100 µm. Quantification of the reactive cells is expressed as the mean ± SD, from three different experiments, four animals/experiment/experimental group, and five independent sections per animal. ^***p<0.001 versus LPS-treated animals. (<b>B</b>) Behavioral analysis. Three weeks after treatment apomorphine-induced rotations were analyzed in control, LPS-injected, and LPS+S14-injected rats. Values represent the means ± SD from three different experiments. ^***p<0.001, <i>versus</i> LPS-injected animals.</p