12 research outputs found
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 columnsâtwo reinforced with steel bars (as reference specimens) and nine totally reinforced with GFRP barsâwere 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.Lâacier et les matĂ©riaux Ă base de polymĂšres renforcĂ©s de fibres (PRF) ont des caractĂ©ristiques physiques et mĂ©caniques diffĂ©rentes. La rĂ©sistance Ă la haute corrosion, le rapport rĂ©sistance vs poids, la non-conductivitĂ© et la bonne rĂ©sistance Ă la fatigue font des barres dâarmature en PRF, un renforcement alternatif aux barres dâarmature en acier, pour des structures dans des environnements agressifs. Cependant, les barres dâarmature en PRF ont un bas module dâĂ©lasticitĂ© et une courbe contrainte-dĂ©formation sous forme linĂ©aire. Ces caractĂ©ristiques soulĂšvent des problĂšmes d'applicabilitĂ© quant Ă lâutilisation de tels matĂ©riaux comme renforcement pour des structures situĂ©es en forte zone sismique. La principale exigence pour les Ă©lĂ©ments structuraux des structures soumises Ă des charges sismiques est la dissipation d'Ă©nergie sans perte de rĂ©sistance connue sous le nom de ductilitĂ©. Dans les structures rigides de type cadre, on s'attend Ă ce que les colonnes soient les premiers Ă©lĂ©ments Ă dissiper l'Ă©nergie dans les structures soumises Ă ces charges.
La prĂ©sente Ă©tude traite de la faisabilitĂ© des colonnes en bĂ©ton armĂ© entiĂšrement renforcĂ©es de barres dâarmature en polymĂšres renforcĂ©s de fibres de verre (PRFV), obtenant une rĂ©sistance et un dĂ©placement latĂ©ral raisonnable par rapport aux exigences spĂ©cifiĂ©es dans divers codes. Onze colonnes Ă grande Ă©chelle ont Ă©tĂ© fabriquĂ©es: deux colonnes renforcĂ©es de barres d'acier (comme spĂ©cimens de rĂ©fĂ©rence) et neuf colonnes renforcĂ©es entiĂšrement de barres en PRFV. Les colonnes ont Ă©tĂ© testĂ©es jusquâĂ la rupture sous une charge quasi-statique latĂ©rale cyclique inversĂ©e et soumises simultanĂ©ment Ă une charge axiale de compression. Les colonnes ont une section carrĂ©e de 400 mm avec une portĂ©e de cisaillement de 1650 mm pour simuler une colonne de 3,7 m de hauteur dans un bĂątiment typique avec le point dâinflexion situĂ© Ă la mi-hauteur. Les paramĂštres testĂ©s sont : le taux dâarmature longitudinal (0,63%, 0,95% et 2,14 %), l'espacement des Ă©triers (80mm, 100mm, 150 mm), les diffĂ©rentes configurations (C1, C2, C3 et C4) et le niveau de charge axiale (20%, 30 % et 40%).
Les rĂ©sultats des essais montrent clairement que les colonnes en bĂ©ton renforcĂ©es de PRFV et bien conçues peuvent atteindre des niveaux de dĂ©formation Ă©levĂ©s sans rĂ©duction de rĂ©sistance. Un niveau acceptable de dissipation d'Ă©nergie, par rapport aux colonnes en bĂ©ton armĂ© avec de lâarmature en acier, est atteint par les colonnes en bĂ©ton armĂ© de PRFV. L'Ă©nergie dissipĂ©e des colonnes en bĂ©ton armĂ© de PRFV Ă©tait respectivement de 75% et 70% des colonnes en acier Ă un rapport dĂ©placement latĂ©ral de 2,5% et 4%. Un dĂ©placement supĂ©rieur a Ă©tĂ© atteint par les colonnes en PRFV jusqu'Ă 10% sans perte significative de rĂ©sistance. La capacitĂ© dâun dĂ©placement supĂ©rieur et lâĂ©nergie dissipĂ©e acceptable permettent aux colonnes en PRFV de participer au moment rĂ©sistant dans des rĂ©gions sujettes Ă des activitĂ©s sismiques. Les rapports des dĂ©placements expĂ©rimentaux ultimes ont Ă©tĂ© comparĂ©s avec les rapports estimĂ©s en utilisant lâĂquation de confinement du code CSA S806-12. Ă partir de la comparaison, il a Ă©tĂ© trouvĂ© que lâĂquation de confinement sous-estime les valeurs des rapports de dĂ©placement, donc les rapports de dĂ©placement expĂ©rimentaux Ă©taient utilisĂ©s pour modifier la zone de renforcement transversal du code CSA S806-12. Le comportement hystĂ©rĂ©tique encourage Ă proposer une procĂ©dure de conception pour que les colonnes fassent partie des cadres rigides Ă ductilitĂ© modĂ©rĂ©e et rĂ©sistant au moment. Cependant, l'Ă©laboration de guides de conception dĂ©pend de la dĂ©termination des dĂ©formations Ă©lastiques et inĂ©lastiques et de l'Ă©valuation du facteur de modification de la force sismique et de la longueur de la rotule plastique pour les colonnes en bĂ©ton armĂ© renforcĂ©es de PRFV. Les rĂ©sultats expĂ©rimentaux des colonnes renforcĂ©es de PRFV Ă©tudiĂ©es ont Ă©tĂ© utilisĂ©s pour justifier la ligne directrice de conception, ce qui prouve lâefficacitĂ© des Ă©quations de conception proposĂ©es
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 1.38â 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)
Identification of new allosteric sites and modulators of AChE through computational and experimental tools
<p>Allosteric sites on proteins are targeted for designing more selective inhibitors of enzyme activity and to discover new functions. Acetylcholinesterase (AChE), which is most widely known for the hydrolysis of the neurotransmitter acetylcholine, has a peripheral allosteric subsite responsible for amyloidosis in Alzheimerâs disease through interaction with amyloid ÎČ-peptide. However, AChE plays other non-hydrolytic functions. Here, we identify and characterise using computational tools two new allosteric sites in AChE, which have allowed us to identify allosteric inhibitors by virtual screening guided by structure-based and fragment hotspot strategies. The identified compounds were also screened for <i>in vitro</i> inhibition of AChE and three were observed to be active. Further experimental (kinetic) and computational (molecular dynamics) studies have been performed to verify the allosteric activity. These new compounds may be valuable pharmacological tools in the study of non-cholinergic functions of AChE.</p
Deciphering the Inhibition of the Neuronal Calcium Sensor 1 and the Guanine Exchange Factor Ric8a with a Small Phenothiazine Molecule for the Rational Generation of Therapeutic Synapse Function Regulators
Proteinâprotein
interactions (PPIs) are known to play an
essential role between the neuronal calcium sensor 1 (NCS-1) and the
guanine exchange factor Ric8a to regulate synapse function, emerging
as a druggable interface for synaptopathies such as the fragile X
syndrome (FXS). Recently, the phenothiazine FD44 has been identified
as an inhibitor of this PPI, decreasing the abnormally high synapse
number and enhancing associative learning in a FXS animal model. Here,
we have integrated advanced experimental and computational studies
to obtain important structural insights into <i>Drosophila</i> NCS-1/FD44 recognition to understand the basis of its affinity and
specificity and generate improved PPI regulators. This has allowed
the identification of a new small drug-like molecule, IGS-1.76, which
efficiently inhibits the human NCS-1/Ric8a complex with improved binding
potency. The crystal structure of the <i>Drosophila</i> NCS-1/IGS-1.76
complex demonstrates that the new inhibitor, although chemically different
from FD44, shares the same mechanism of action and constitutes a new
hit candidate for FXS
Deciphering the Inhibition of the Neuronal Calcium Sensor 1 and the Guanine Exchange Factor Ric8a with a Small Phenothiazine Molecule for the Rational Generation of Therapeutic Synapse Function Regulators
Proteinâprotein
interactions (PPIs) are known to play an
essential role between the neuronal calcium sensor 1 (NCS-1) and the
guanine exchange factor Ric8a to regulate synapse function, emerging
as a druggable interface for synaptopathies such as the fragile X
syndrome (FXS). Recently, the phenothiazine FD44 has been identified
as an inhibitor of this PPI, decreasing the abnormally high synapse
number and enhancing associative learning in a FXS animal model. Here,
we have integrated advanced experimental and computational studies
to obtain important structural insights into <i>Drosophila</i> NCS-1/FD44 recognition to understand the basis of its affinity and
specificity and generate improved PPI regulators. This has allowed
the identification of a new small drug-like molecule, IGS-1.76, which
efficiently inhibits the human NCS-1/Ric8a complex with improved binding
potency. The crystal structure of the <i>Drosophila</i> NCS-1/IGS-1.76
complex demonstrates that the new inhibitor, although chemically different
from FD44, shares the same mechanism of action and constitutes a new
hit candidate for FXS
Deciphering the Inhibition of the Neuronal Calcium Sensor 1 and the Guanine Exchange Factor Ric8a with a Small Phenothiazine Molecule for the Rational Generation of Therapeutic Synapse Function Regulators
Proteinâprotein
interactions (PPIs) are known to play an
essential role between the neuronal calcium sensor 1 (NCS-1) and the
guanine exchange factor Ric8a to regulate synapse function, emerging
as a druggable interface for synaptopathies such as the fragile X
syndrome (FXS). Recently, the phenothiazine FD44 has been identified
as an inhibitor of this PPI, decreasing the abnormally high synapse
number and enhancing associative learning in a FXS animal model. Here,
we have integrated advanced experimental and computational studies
to obtain important structural insights into <i>Drosophila</i> NCS-1/FD44 recognition to understand the basis of its affinity and
specificity and generate improved PPI regulators. This has allowed
the identification of a new small drug-like molecule, IGS-1.76, which
efficiently inhibits the human NCS-1/Ric8a complex with improved binding
potency. The crystal structure of the <i>Drosophila</i> NCS-1/IGS-1.76
complex demonstrates that the new inhibitor, although chemically different
from FD44, shares the same mechanism of action and constitutes a new
hit candidate for FXS
Deciphering the Inhibition of the Neuronal Calcium Sensor 1 and the Guanine Exchange Factor Ric8a with a Small Phenothiazine Molecule for the Rational Generation of Therapeutic Synapse Function Regulators
Proteinâprotein
interactions (PPIs) are known to play an
essential role between the neuronal calcium sensor 1 (NCS-1) and the
guanine exchange factor Ric8a to regulate synapse function, emerging
as a druggable interface for synaptopathies such as the fragile X
syndrome (FXS). Recently, the phenothiazine FD44 has been identified
as an inhibitor of this PPI, decreasing the abnormally high synapse
number and enhancing associative learning in a FXS animal model. Here,
we have integrated advanced experimental and computational studies
to obtain important structural insights into <i>Drosophila</i> NCS-1/FD44 recognition to understand the basis of its affinity and
specificity and generate improved PPI regulators. This has allowed
the identification of a new small drug-like molecule, IGS-1.76, which
efficiently inhibits the human NCS-1/Ric8a complex with improved binding
potency. The crystal structure of the <i>Drosophila</i> NCS-1/IGS-1.76
complex demonstrates that the new inhibitor, although chemically different
from FD44, shares the same mechanism of action and constitutes a new
hit candidate for FXS
Deciphering the Inhibition of the Neuronal Calcium Sensor 1 and the Guanine Exchange Factor Ric8a with a Small Phenothiazine Molecule for the Rational Generation of Therapeutic Synapse Function Regulators
Proteinâprotein
interactions (PPIs) are known to play an
essential role between the neuronal calcium sensor 1 (NCS-1) and the
guanine exchange factor Ric8a to regulate synapse function, emerging
as a druggable interface for synaptopathies such as the fragile X
syndrome (FXS). Recently, the phenothiazine FD44 has been identified
as an inhibitor of this PPI, decreasing the abnormally high synapse
number and enhancing associative learning in a FXS animal model. Here,
we have integrated advanced experimental and computational studies
to obtain important structural insights into <i>Drosophila</i> NCS-1/FD44 recognition to understand the basis of its affinity and
specificity and generate improved PPI regulators. This has allowed
the identification of a new small drug-like molecule, IGS-1.76, which
efficiently inhibits the human NCS-1/Ric8a complex with improved binding
potency. The crystal structure of the <i>Drosophila</i> NCS-1/IGS-1.76
complex demonstrates that the new inhibitor, although chemically different
from FD44, shares the same mechanism of action and constitutes a new
hit candidate for FXS
Deciphering the Inhibition of the Neuronal Calcium Sensor 1 and the Guanine Exchange Factor Ric8a with a Small Phenothiazine Molecule for the Rational Generation of Therapeutic Synapse Function Regulators
Proteinâprotein
interactions (PPIs) are known to play an
essential role between the neuronal calcium sensor 1 (NCS-1) and the
guanine exchange factor Ric8a to regulate synapse function, emerging
as a druggable interface for synaptopathies such as the fragile X
syndrome (FXS). Recently, the phenothiazine FD44 has been identified
as an inhibitor of this PPI, decreasing the abnormally high synapse
number and enhancing associative learning in a FXS animal model. Here,
we have integrated advanced experimental and computational studies
to obtain important structural insights into <i>Drosophila</i> NCS-1/FD44 recognition to understand the basis of its affinity and
specificity and generate improved PPI regulators. This has allowed
the identification of a new small drug-like molecule, IGS-1.76, which
efficiently inhibits the human NCS-1/Ric8a complex with improved binding
potency. The crystal structure of the <i>Drosophila</i> NCS-1/IGS-1.76
complex demonstrates that the new inhibitor, although chemically different
from FD44, shares the same mechanism of action and constitutes a new
hit candidate for FXS
Deciphering the Inhibition of the Neuronal Calcium Sensor 1 and the Guanine Exchange Factor Ric8a with a Small Phenothiazine Molecule for the Rational Generation of Therapeutic Synapse Function Regulators
Proteinâprotein
interactions (PPIs) are known to play an
essential role between the neuronal calcium sensor 1 (NCS-1) and the
guanine exchange factor Ric8a to regulate synapse function, emerging
as a druggable interface for synaptopathies such as the fragile X
syndrome (FXS). Recently, the phenothiazine FD44 has been identified
as an inhibitor of this PPI, decreasing the abnormally high synapse
number and enhancing associative learning in a FXS animal model. Here,
we have integrated advanced experimental and computational studies
to obtain important structural insights into <i>Drosophila</i> NCS-1/FD44 recognition to understand the basis of its affinity and
specificity and generate improved PPI regulators. This has allowed
the identification of a new small drug-like molecule, IGS-1.76, which
efficiently inhibits the human NCS-1/Ric8a complex with improved binding
potency. The crystal structure of the <i>Drosophila</i> NCS-1/IGS-1.76
complex demonstrates that the new inhibitor, although chemically different
from FD44, shares the same mechanism of action and constitutes a new
hit candidate for FXS