Behavior of hollow-core fiber reinforced polymer-concrete-steel bridge columns under extreme loading

This study introduces an investigation of the behavior of innovative, resilient, and quickly-constructed hollow-core fiber reinforced polymer-concrete-steel (HC-FCS) bridge columns under extreme loading. The HC-FCS column consists of a concrete wall sandwiched between an outer fiber reinforced polymer (FRP) tube and an inner steel tube. The steel tube was embedded into a reinforced concrete footing with an embedded length of 1.6-1.8 times the diameter of the steel tube. The FRP tube only confined the concrete wall and truncated at the top of the footing level. The hollow steel tube was the only reinforcement for shear and flexure inside the HC-FCS column. The steel and FRP tubes act together as stay-in-place formworks. The results obtained from testing the HCFCS columns under seismic loading have been compared with those from testing the conventional reinforced concrete (RC) column. Results showed that the HC-FCS column exhibited a high lateral drift reaching 15.2%, while the well-detailed solid cross-section RC column reached a drift of 10.9%. The HC-FCS column dissipated energy reaching 1.9 times that of the RC column. A simple analytical model and preliminary design guidelines were presented to help implement this new technology. Vehicle collision with RC and HC-FCS bridge columns was also presented in this study using LS-DYNA software. The first equation for estimating the equivalent static force of the vehicle collision, based on the vehicle\u27s mass and velocity, was developed. This approach will allow departments of transportation (DOTs) to design different bridge columns for different impact force demands depending on the anticipated truck loads and velocities from roads survey. In general, the peak dynamic force values of the HC-FCS columns were lower than those of the RC columns when they were subjected to vehicle collision, which could save lives and reduce damage to the bridge column and the vehicle --Abstract, page v

Dynamic and Static Behavior of Hollow-Core FRP-Concrete-Steel and Reinforced Concrete Bridge Columns under Vehicle Collision

This paper presents the difference in behavior between hollow-core fiber reinforced polymer-concrete-steel (HC-FCS) columns and conventional reinforced concrete (RC) columns under vehicle collision in terms of dynamic and static forces. The HC-FCS column consisted of an outer FRP tube, an inner steel tube, and a concrete shell sandwiched between the two tubes. The steel tube was hollow inside and embedded into the concrete footing with a length of 1.5 times the tube diameter while the FRP tube stopped at the top of footing. The RC column had a solid cross-section. The study was conducted through extensive finite element impact analyses using LS-DYNA software. Nine parameters were studied including the concrete material model, unconfined concrete compressive strength, material strain rate, column height-to-diameter ratio, column diameter, column top boundary condition, axial load level, vehicle velocity, and vehicle mass. Generally, the HC-FCS columns had lower dynamic forces and higher static forces than the RC columns when changing the values of the different parameters. During vehicle collision with either the RC or the HC-FCS columns, the imposed dynamic forces and their equivalent static forces were affected mainly by the vehicle velocity and vehicle mass

Concrete-Filled-Large Deformable FRP Tubular Columns under Axial Compressive Loading

The behavior of concrete-filled fiber tubes (CFFT) polymers under axial compressive loading was investigated. Unlike the traditional fiber reinforced polymers (FRP) such as carbon, glass, aramid, etc., the FRP tubes in this study were designed using large rupture strains FRP which are made of recycled materials such as plastic bottles; hence, large rupture strain (LRS) FRP composites are environmentally friendly and can be used in the context of green construction. This study performed finite element (FE) analysis using LS-DYNA software to conduct an extensive parametric study on CFFT. The effects of the FRP confinement ratio, the unconfined concrete compressive strength (ƒc\u27), column size, and column aspect ratio on the behavior of the CFFT under axial compressive loading were investigated during this study. A comparison between the behavior of the CFFTs with LRS-FRP and those with traditional FRP (carbon and glass) with a high range of confinement ratios was conducted as well. A new hybrid FRP system combined with traditional and LRS-FRP is proposed. Generally, the CFFTs with LRS-FRP showed remarkable behavior under axial loading in strength and ultimate strain. Equations to estimate the concrete dilation parameter and dilation angle of the CFFTs with LRS-FRP tubes and hybrid FRP tubes are suggested

EOR用ポリマーのレオロジー特性と油層岩石中の流動抵抗

制度:新 ; 文部省報告番号:甲858号 ; 学位の種類:工学博士 ; 授与年月日:1991-02-07 ; 早大学位記番号:新1666 ; 理工学図書館請求番号:1419早稲田大

Torsional Behavior of Hollow-Core FRP-Concrete-Steel Bridge Columns

This paper presents the behavior of hollow-core fiber reinforced polymer-concrete-steel (HC-FCS) column under pure torsion loading with constant axial load. The HCFCS consists of outer FRP tube and inner steel tube with concrete shell sandwiched between the two tubes. The FRP tube was stopped at the surface of the footing and provided confinement to the concrete shell from outer direction. The steel tube was embedded into the footing to a length of 1.8 times to the diameter of the steel tube. The longitudinal and transversal reinforcements of the column were provided by the steel tube only. A large-scale HC-FCS column with a diameter of 610 mm and height of applied load of 2,438 mm with aspect ratio of 4 was investigated during this study. The study revealed that the torsional behavior of HC-FCS column mainly depended on the stiffness of the steel tube and the interactions among the column components (concrete shell, steel tube, and FRP tube)

Hollow-Core FRP-Concrete-Steel Bridge Columns under Torsional Loading

This paper presents the behavior of hollow-core fiber-reinforced polymer-concrete-steel (HC-FCS) columns under cyclic torsional loading combined with constant axial load. The HC-FCS consists of an outer fiber-reinforced polymer (FRP) tube and an inner steel tube, with a concrete shell sandwiched between the two tubes. The FRP tube was stopped at the surface of the footing, and provided confinement to the concrete shell from the outer direction. The steel tube was embedded into the footing to a length of 1.8 times the diameter of the steel tube. The longitudinal and transversal reinforcements of the column were provided by the steel tube only. A large-scale HC-FCS column with a diameter of 24 in. (610 mm) and applied load height of 96 in. (2438 mm) with an aspect ratio of four was investigated during this study. The study revealed that the torsional behavior of the HC-FCS column mainly depended on the stiffness of the steel tube and the interactions among the column components (concrete shell, steel tube, and FRP tube). A brief comparison of torsional behavior was made between the conventional reinforced concrete columns and the HC-FCS column. The comparison illustrated that both column types showed high initial stiffness under torsional loading. However, the HC-FCS column maintained the torsion strength until a high twist angle, while the conventional reinforced concrete column did not

Rupture bilatérale des tendons rotuliens chez un sujet jeune sans notion de maladies systémiques ou de traitement par les corticostéroïdes: à propos d’un cas et revue de la literature

Les lésions du tendon rotulien sont moins communes que celles du tendon quadricipital. Les lésions  bilatérales sont encore plus rares et sont souvent associées à une notion de tendinopathie, d'injection de corticoïdes ou de maladies systémiques tels que le lupus érythémateux, l'ostéomalacie ou l'insuffisance rénale chronique. Nous rapportons le cas d'un patient de 26 ans victime d'une rupture bilatérale du tendon rotulien suite à une réception de saut. Le patient n'avait pas d'antécédents de tendinopathie ni de  maladies systémiques. Le diagnostic a été suspecté devant une position anormalement haute des deux  rotules avec une impossibilité d'extension active des deux jambes. L'échographie a confirmé le diagnostic. Le patient a été traité par la technique de laçage selon Judet protégée par un cadrage. La  rupture bilatérale du tendon rotulien est rare. La plupart des patients rapportent une notion de maladie systémique ou un antécédents de chirurgie du genou. Nous rapportons le cas d'une lésion rare dans la littérature, une rupture bilatérale des tendons rotuliens sans notions de maladies auto-immunes ni de traitement avec des corticostéroïdes. Les lésions bilatérales présentent certaines particularités  diagnostiques et thérapeutiques.En effet l'objectivation d'une rotule haute peut être rendu difficile par un aspect controlatéral semblable. Concernant le volet thérapeutique, deux difficultés sont à noter la première réside dans l'absence de référence comparative pour la hauteur patellaire. La deuxième difficulté est l'obligation de différer l'appui à 45 jours. Ce qui est contraignant pour le patient. La technique de laçage décrite par judet couplée à un cadrage provisoire protégeant la suture nous a donné des résultats satisfaisants.Key words: Rupture bilatérale, tendon rotulien, maladies systémiques, corticostéroïde

Technique de Blount dans le traitement des fractures supra condyliennes du coude chez l’enfant: à propos de 68 cas

La fracture de la palette humérale est la plus fréquente des fractures du coude de l’enfant. La méthode de BLOUNT, constitue une perspective thérapeutique longtemps connue. Elle consiste en une réduction sous  contrôle scopique de la fracture et une contention en hyper flexion du coude. Notre série a porté sur l’étude de 68 cas de fractures supra condyliennes chez des enfants traités dans le service des urgences chirurgicales pédiatriques de l’hôpital d’enfant de Rabat entre janvier 2009 et janvier 2012. Nous comparons nos résultats  avec les données de la littérature.Key words: Humérus, fracture supra condyliennes, enfant, traitement orthopédiqu

Rupture du tendon rotulien avec fracture fermée distale du fémur homolatéral

Un patient de 45 ans a subi un traumatisme du genou droit à la suite d'un accident de la voie publique occasionnant chez lui une fracture distale supra condylienne comminutive du fémur droit et une rupture du tendon rotulien ipsilatérale. Cette association est exceptionnelle et aucun cas n'a été retrouvé dans la littérature. Un diagnostic précis clinique et radiologique suivi d'une prise en charge précoce et adaptée par une ostéosynthèse interne et une rééducation fonctionnelle précoce et adaptée ont permis d'obtenir de bons résultats à long terme

Effects of pomegranate juice supplementation on oxidative stress biomarkers following weightlifting exercise

The aim of this study was to test the hypothesis that pomegranate juice supplementation would blunt acute and delayed oxidative stress responses after a weightlifting training session. Nine elite weightlifters (21.0 ±1 years) performed two Olympic-Weightlifting sessions after ingesting either the placebo or pomegranate juice supplements. Venous blood samples were collected at rest and 3 min and 48 h after each session. Compared to the placebo condition, pomegranate juice supplementation attenuated the increase in malondialdehyde (-12.5%; p < 0.01) and enhanced the enzymatic (+8.6% for catalase and +6.8% for glutathione peroxidase; p < 0.05) and non-enzymatic (+12.6% for uric acid and +5.7% for total bilirubin; p < 0.01) antioxidant responses shortly (3 min) after completion of the training session. Additionally, during the 48 h recovery period, pomegranate juice supplementation accelerated (p < 0.05) the recovery kinetics of the malondialdehyde (5.6%) and the enzymatic antioxidant defenses compared to the placebo condition (9 to 10%). In conclusion, supplementation with pomegranate juice has the potential to attenuate oxidative stress by enhancing antioxidant responses assessed acutely and up to 48 h following an intensive weightlifting training session. Therefore, elite weightlifters might benefit from blunted oxidative stress responses following intensive weightlifting sessions, which could have implications for recovery between training sessions