Comportement des piles de ponts sous l'effet multidirectionnel des mouvements sismiques

RÉSUMÉ Une étude approfondie a été réalisée dans le cadre de cette thèse pour étudier le comportement sismique des colonnes de ponts sous l’effet multidirectionnel des mouvements sismiques. L'étude comprend une série d’analyses dynamiques linéaires et non linéaires sur un ensemble de structures de ponts réguliers représentatifs d’un grand nombre de ponts communs du réseau routier nord-américain. L’étude comprend aussi une série de tests cycliques bidirectionnels réalisés sur quatre spécimens à l’échelle 1:0.5 de colonnes de ponts rectangulaires en béton armé. Deux sites nord-américains à l'aléa sismique modéré ont été considérés : Montréal, Qc, à l'est, et Vancouver, en Colombie-Britannique, le long de la côte ouest. Pour les deux sites, des ensembles de mouvements sismiques, composés de paires d’accélérogrammes historiques et artificiels, ont été utilisés. La première partie de l'étude visait à examiner la validité et la fiabilité de la règle du pourcentage (30% ou 40%), à prédire la demande sismique dans les colonnes de ponts soumis à des mouvements sismiques bidirectionnels. Une série d’analyses dynamiques transitoires multiples a été réalisée sur un ensemble de neuf modèles de ponts présentant des typologies différentes pour déterminer la réponse sismique critique exacte des colonnes de ponts sous l’action simultanée des composantes horizontales des mouvements sismiques. Les spectres d’accélération des composantes horizontales des mouvements sismiques ont été ensuite utilisés dans le cadre d’analyses dynamiques spectrales pour déterminer séparément les réponses maximales selon les deux directions principales des ponts. Les réponses critiques sous l’action simultanée des composantes horizontales des mouvements sismiques ont été estimées en combinant les réponses maximales obtenues dans les deux directions selon la règle des 30%, tel que spécifié dans le CSA S6 et l’AASHTO. La comparaison des réponses, en termes de moments bi-axiaux (Mx, My), calculés à la base des colonnes, montre que la règle des 30% telle que spécifiée actuellement par les codes parasismiques peut conduire à une prédiction non conservatrice de la demande sismique bidirectionnelle dans le cas des colonnes de ponts. ----------ABSTRACT A comprehensive study has been conducted to investigate the seismic behaviour of bridge columns under bidirectional earthquake ground motions. The study comprises a series of linear elastic and non-linear dynamic analyses on a set of regular bridge structures representative of common type bridges that are encountered the most in North American highways, as well as bidirectional cyclic testing of four half-scale rectangular reinforced concrete bridge columns. The study was conducted for two North American sites of moderate seismic hazard: Montreal, QC, in the East, and Vancouver, BC, along the West coast. For both sites, historical and simulated ground motion earthquake ensembles were considered. The first part of the study was aimed at investigating the adequacy and effectiveness of the 30%-rule, at predicting the seismic demand on bridge columns when subjected to bi-directional earthquake motions. A series of multiple time-history analyses performed on nine generic bridge models to determine the exact seismic critical bi-axial response of the bridge columns under pairs of orthogonal seismic ground motion time-histories. Response spectrum analyses were also carried out, using the acceleration spectra of the orthogonal ground motion components, to determine the maximum bi-axial response in each direction and the critical bi-axial response was estimated using the 30%-Rule, as specified by the CSA S6 and the AASHTO bridge design code and regulations. Comparison of the response at the columns base, in terms of interacting moments (Mx, My), shows that the 30%-Rule as currently specified by the codes and regulations may lead to unconservative prediction of the seismic demand on bridge columns. The scatter in the results clearly indicates a dependency of the combination rule on the characteristics of the ground motions and the bridge structures, suggesting that there might be a need for improving the combination rule. The weighted percentage α of the combination rule was found to be closely related to the ratio of intensities of the ground motions earthquake principal components. For eastern site (Montreal), the intensity of the major principal component is on average 2.05 times larger than the intensity of the minor principal component

NDM-502: INTEGRATION OF SITE CONDITIONS INFORMATION USING GEOGRAPHIC INFORMATION SYSTEM FOR THE SEISMIC EVALUATION OF BRIDGES

While seismic hazard is generally moderate in eastern Canada, the seismic risk in urban area is increased by the density of the population, the value and the age of the infrastructure and the relative importance of the economic activities. Among the consequences of a seismic event, damages to infrastructures, such as bridges and overpasses, may compromise the safety of users and the free movement of people and goods. According to modern seismic codes and regulations, structures designed for seismic loading should sustain moderate to severe earthquakes with minimal and reparable damages and without collapse. However, older structures build prior to the introduction of seismic requirements in codes and standards, are more vulnerable and exposed to a high seismic risk. Geotechnical and geological site conditions may result in severe damages to the structures and contribute to their seismic vulnerability. This project proposes to extract these information using geographical information system (GIS) tools at the bridge sites and integrate this information in the seismic evaluation procedures. Local soil amplification and induced effects are integrated into scoring evaluation procedures and seismic risk studies. In this paper, the amplification phenomenon will be investigated by the compilation of existing data for the Saint-Lawrence valley and ambient noise measurements on soil and bridges. The aim of this study is to develop a susceptibility scale to the amplification effect based on GIS information. The results will contribute to a better estimation of the seismic vulnerability of bridges and overpasses to prioritize mitigation as well as post-earthquake interventions

A rare breed: Wild-type braf and ighv expression in a 29 year old lady with classical hairy cell leukemia

The V600 BRAF mutation has been described as a key mutation in the pathogenesis of classical hairy cell leukemia (c-HCL) cases without expression of a mutant immunoglobulin heavy chain (IgHV). Here we present a rare case of c-HCL with neither V600 BRAF mutation nor the aforementioned IgHV variant successfully treated with cladribine and review the current literature on its use in women of childbearing age/pregnancy

Synthesis of ammonia directly from wet air at intermediate temperature

For the first time, ammonia has been directly synthesised from wet air at intermediate temperature. Ce0.8Gd0.2O2−δ (CGO)–(Li,Na,K)2CO3 electrolyte together with a new perovskite oxide Pr0.6Ba0.4Fe0.8Cu0.2O3−δ were used for electrochemical synthesis of ammonia. An ammonia formation rate of 1.07 × 10−6 mol s−1 m−2 was obtained at 400 °C when applied a voltage of 1.4 V, while wet air was introduced to the single chamber reactor. This is just slightly lower than the value of 1.83 × 10−6 mol s−1 m−2 when wet N2 was fed under the same experimental conditions. These values are two to three orders of magnitude higher than the reported ammonia formation rates when synthesised from N2 and H2O at ∼600 °C. The perovskite catalysts are also low cost compared to the Ru/MgO and Pt/C catalysts in previous reports

Étude préliminaire du traitement d’effluents contenant de l’encre de seiche par centrifugation et procédés à membranes

Il s’agit d’une étude préliminaire sur le traitement d’effluents de conditionnement de la seiche avant congélation en vue de réduire la charge polluante des rejets et de valoriser l’encre qu’ils contiennent. Deux types de procédés ont été mis en oeuvre : d’une part, la centrifugation, qui permet de fractionner la suspension d’encre de seiche entre un culot noir à DCO (Demande Chimique en Oxygène) élevée et un surnageant limpide et, d’autre part, l’ultrafiltration (UF) et la microfiltration (MF). Les flux de perméat obtenus par les deux procédés à membranes sont du même ordre de grandeur (25 à 30 L·h‑1·m‑2 sous 1,5 bar). La rétention moyenne en DCO est de 65 % et la rétention en COT (Carbone Organique Total) et azote protéique (NTK) de plus de 95 %. Cependant le colmatage irréversible de la membrane de MF conduit à préférer l’UF, plus facilement régénérable.Industries that condition fish products have to cope with the problem of processing their usually protein-rich wastewaters. An example of such an industry that discards a large amount of wastewater is the CALEMBO Company (Sfax-Tunisia), which uses 50 m3 per metric ton a day to condition cuttlefish for freezing. In order to conserve water, high-salinity bore water is sometimes used. This high salinity water is responsible for the difficulties encountered during the biological treatment of wastewaters and the recovery of valuable by-products. In this respect, membrane processes, used in the treatment and exploitation of effluents from industries that process sea products, are very attractive. The first membrane filtration trials on sea-product effluents date back to the 1980’s, but they did not result in major developments. Legislative pressures and the increasing costs of water and effluent-processing, as well as the improvement of membrane efficiencies, have made membrane treatment processes much more interesting for wastewater treatment processes. The GEPEA Laboratory at Nantes University has carried out research on membrane technologies to clean up polluted process waters, enhance substances such as soluble fish proteins, and to recover substances responsible for the flavour of bivalves and shellfish.This paper presents preliminary research on the treatment and exploitation of water used in cuttlefish conditioning. Treatment processes used include centrifugation, microfiltration and ultrafiltration. Centrifugation is used to determine the distribution of the effluent between the black residue and the clear supernatant, whereas membrane processing is used to reduce wastewater pollution and concentrate pigments.The effluent studied was reconstituted from pure cuttlefish-ink samples taken directly from the animal and salt waters of the same salinity as the bore water used by the CALEMBO Company (Table 1). The samples were reconstituted in ratios of 1 to 50 for centrifugation and 1 to 100 for membrane filtration. Centrifugation trials were carried out using a KR 22i type JOUAN centrifuge, whereas ultrafiltration and microfiltration trials were carried out using the laboratory apparatus represented in figure 1. The main characteristics of membranes used are indicated in table 2. Operating conditions were determined according to the capacities of the feed pump: transmembrane pressure Ptm = 1.5 bar, circulation velocity U = 1.5 m·s‑1 and temperature T = 25°C. The parameters measured on initial feed solutions and the fractions obtained were COD (Chemical Oxygen Demand), TOC (Total Organic Carbon) and nitrogen content (NTK). Filtration trials were carried out according to two different procedures, either with constant feed composition to determine the best operating conditions, or with increasing effluent concentration together with monitoring of the Volumetric Reduction Factor (VRF).Centrifugation of the cuttlefish-ink suspension produced two phases: a very dense black residue and relatively clear supernatant. The volumetric distribution and the COD and TOC contents of the different fractions are presented in table 3. The supernatant represented about 75% of crude effluent volume. Organic matter was concentrated in the residue and consisted primarily of suspended particles.At a constant concentration, the ultrafiltration (UF) and microfiltration (MF) processes behaved differently. A rapid drop in flux in the first minutes followed by stabilization at 30 L·h‑1·m‑2 after 30 min was observed for the MF process, whereas a rapid stabilization at approximately 25 L·h‑1·m‑2 was observed for the UF process. The drop in flux at the beginning of MF process may be due to the partial fouling of the membrane pores by melanin particles ranging in sizes from 55 to 160 nm, which are of the same order of magnitude as the membrane pores of 100 nm. On the other hand, the small decrease in flux in the case of ultrafiltration resulted essentially from the formation of a polarization layer and possible interactions between the membrane material and the solution.Batch-concentration trials were carried out for 5 and 4 h using UF and MF respectively, the operating time being dictated by the dead volume of the equipment (0.75 L). The permeate flux variation as a function of the volumetric reduction factor (VRF) is illustrated in figure 3. The MF flux was slightly higher despite the higher initial concentration of organic substances. For a VRF of 2.64 (final concentration), J = 2.8 L·h‑1·m‑2 for MF and 15.2 L·h‑1·m‑2 for UF. Despite the significantly different permeabilities of the MR and UF membranes to pure water (2690 against 34 L·h‑1·m‑2·bar‑1), their very similar J values are a consequence of the internal pore fouling of the MF membranes.Analyses performed on the initial feed samples, and on the different fractions of ink suspensions obtained by MF and UF following concentration, are presented in table 5. Retention ratios for UF were very slightly higher than those found for MF, about 65% for COD, 98% for TOC and 95% for NTK. From the point of view of pollution remediation, and considering permeate COD values, the efficiency of the membrane technique does not seem sufficient.Following ultrafiltration, membrane regeneration was possible by simply rinsing the membrane with water. On the other hand, the same procedure proved inefficient for the microfiltration (PVDF) membrane. The black pigment remained stuck to the membrane surface and most likely inside the pores as well. Furthermore, chemical regeneration (NaOH 0.1 M, 20 min, 25°C) was not enough to recover the membrane’s initial permeability.To conclude, the ultrafiltration process is better adapted to the treatment of cuttlefish washing wastewater. However, considering the level of residual COD in the ultrafiltration permeate, more efficient post-treatment techniques must be developed

Clinical characteristics and selection of treatment modality for patients with vitreomacular traction:real-world implementation of NICE guidance (TA297)

Aim: To investigate the qualitative aspects in patient selection and the quantitative impact of disease burden in real world treatment of vitreomacular traction (VMT) and implementation of the National Institute for Health and Care Excellence (NICE) guidance (TA297). Methods: A monocentric, retrospective review of consecutive patients undergoing optical coherence tomography (OCT) imaging over a 3 month period. Patients with VMT in at least one eye were identified for further data collection on laterality, visual acuity, symptoms, presence of epiretinal membrane, macular hole and treatment selection. Results: A total of 3472 patients underwent OCT imaging with a total of 6878 eyes scanned. Out of 87 patients, 74 patients had unilateral VMT (38 right, 36 left) and 13 patients had bilateral VMT. Eighteen patients with unilateral VMT satisfied NICE criteria of severe sight problems in the affected eye. Eight were managed for a coexisting pathology, one refused treatment, one patient did not attend, two closed spontaneously, and one received ocriplasmin prior to the study start date. Only two patients with unilateral VMT received ocriplasmin and three underwent vitrectomy. Those failing to meet NICE criteria for unilateral VMT were predominantly asymptomatic (n=49) or had coexisting ERM (n=5) or both (n=2). Conclusion: Ocriplasmin provides an alternative treatment for patients with symptomatic VMT. Our data shows that the majority of patients with VMT do not meet NICE TA297 primarily due to lack of symptoms. Those meeting NICE criteria, but not treated, tended to have coexisting macular pathology. Variation in patient selection due to subjective factors not outlined in NICE guidance suggests that real world outcomes of ocriplasmin therapy should be interpreted with caution

Functional Identification of Valerena-1,10-diene Synthase, a Terpene Synthase Catalyzing a Unique Chemical Cascade in the Biosynthesis of Biologically Active Sesquiterpenes in Valeriana officinalis

Valerian is an herbal preparation from the roots of Valeriana officinalis used as an anxiolytic and sedative and in the treatment of insomnia. The biological activities of valerian are attributed to valerenic acid and its putative biosynthetic precursor valerenadiene, sesquiterpenes, found in V. officinalis roots. These sesquiterpenes retain an isobutenyl side chain whose origin has been long recognized as enigmatic because a chemical rationalization for their biosynthesis has not been obvious. Using recently developed metabolomic and transcriptomic resources, we identified seven V. officinalis terpene synthase genes (VoTPSs), two that were functionally characterized as monoterpene synthases and three that preferred farnesyl diphosphate, the substrate for sesquiterpene synthases. The reaction products for two of the sesquiterpene synthases exhibiting root-specific expression were characterized by a combination of GC-MS and NMR in comparison to the terpenes accumulating in planta. VoTPS7 encodes for a synthase that biosynthesizes predominately germacrene C, whereas VoTPS1 catalyzes the conversion of farnesyl diphosphate to valerena-1,10-diene. Using a yeast expression system, specific labeled [13C]acetate, and NMR, we investigated the catalytic mechanism for VoTPS1 and provide evidence for the involvement of a caryophyllenyl carbocation, a cyclobutyl intermediate, in the biosynthesis of valerena-1,10-diene. We suggest a similar mechanism for the biosynthesis of several other biologically related isobutenyl-containing sesquiterpenes

Inhibitive effect of sodium (E)-4-(4-nitrobenzylidenamino) benzoate on the corrosion of some metals in sodium chloride solution

The inhibition performance of a novel anionic carboxylic Schiff base, sodium (E)-4-(4-nitrobenzylideneamino)benzoate (SNBB), was investigated for various metals, namely low carbon steel F111, pure iron and copper, in neutral 10 mM NaCl solution. Potentiodynamic polarization, scanning vibrating electrode technique (SVET), quantum chemical (QC) calculation, and molecular dynamics (MD) simulation were employed. The potentiodynamic polarization data showed that SNBB acts as an effective corrosion inhibitor for both iron and F111 steel, but it is not effective for the copper. In situ spatially-resolved SVET maps evidenced a major change in surface reactivity for Fe and F111 steel immersed in 10 mM aqueous solution in the absence and in the presence of SNBB. Featureless ionic current density distributions were recorded in the presence of SNBB at both their spontaneous open circuit potential (OCP) and under mild anodic polarization conditions, while major ionic flows were monitored above the metals in the absence of SNBB. On the basis of computer simulations, it is proposed that SNBB produces a stable chelate film on iron and steel surfaces that accounts for the good corrosion inhibition efficiency observed. The different inhibition efficiencies of SNBB molecules on the iron and copper was attributed to the special chemical structure of SNBB molecule and its different chelation ability with the released metal ions on the metal surface. The QC calculations also confirmed the high corrosion inhibition efficiency of SNBB. The MD simulation indicated higher binding energy of SNBB on iron surface compared to that of copper surface. The interaction mode of SNBB on iron and F111 steel surfaces corresponds to a mixed chemical and physical adsorption, and it obeys the Langmuir isother