Flexural and shear strengthening of reinforced concrete beams with a hybrid CFRP solution

An experimental program was carried out for assessing the performance of a hybrid solution composed by CFRP systems for the simultaneous flexural and shear strengthening of RC beams. CFRP laminates, applied according to NSM technique, are used for the flexural strengthening, while U‐shape CFRP discrete strips of wet lay‐up sheet, applied according to the EBR technique, are adopted for the shear strengthening. An anchorage system was applied at the extremities of these CFRP strips in an attempt of avoiding their premature debonding. The experimental results showed the hybrid strengthening solution is very effective, not only in terms of increasing the load carrying capacity of the beams, but also in assuring higher mobilization of the tensile capacity of the CFRP. The performance of the hybrid CFRP configuration that included the anchorage system for the shear strengthening was significantly higher than the one assured by other shear strengthening solutions that were applied in similar RC beams and tested until failure using the same test system adopted in this experimental program. The predictive performance of the ACI formulations proposed for estimating the contribution of CFRP systems for the flexural and shear resistance of RC beams was appraised considering the obtained experimental results.This work was supported by FEDER funds through the Operational Program for Competitiveness Factors ‐ COMPETE and National Funds through FCT ‐ Portuguese Foundation for Science and Technology under the project Spaflamis POCI‐01‐0145‐FEDER‐030956. The authors also acknowledges the support provided by the S&P® and “Empreiteiros Casais”

Investigação no âmbito da utilização de materiais compósitos no reforço de estruturas de betão

Nos últimos anos tem sido crescente a utilização de materiais compósitos no reforço de estruturas de betão armado. Para tal contribui as melhores propriedades mecânicas destes materiais, a sua maior resistência à acção de agentes agressivos e a sua maior leveza e facilidade de aplicação, quando se tem por base de comparação materiais convencionais tais como o aço e o betão. No Subgrupo de Estruturas do Departamento de Engª Civil da Escola de Engª da Universidade do Minho tem-se efectuado investigação experimental e numérica no âmbito da utilização de laminados em fibra de carbono (CFRP) no reforço de estruturas de betão. Estes materiais compósitos têm sido utilizados no reforço à flexão e ao corte de pilares e vigas. A ligação CFRP-adesivo-betão tem sido caracterizada por forma a ser estabelecida a lei que define a transferência de tensões entre os materiais constituintes desta ligação, lei esta a ser implementada num modelo de interface, no quadro do método dos elementos finitos. Os resultados mais significativos obtidos na investigação efectuada são apresentados no presente trabalho

Near surface mounted CFRP-based technique for the strengthening of concrete structures

To assess the effectiveness of the Near Surface Mounted (NSM) strengthening technique, an experimental program was carried out involving reinforced concrete (RC) columns and beams. In columns failing in bending the present work shows that the failure strain of the Carbon Fiber Reinforced Polymer (CFRP) laminates can be attained using the NSM technique. Beams failing in bending were also strengthened with CFRP laminates in order to double their load carrying capacity. This goal was attained and maximum strain levels of about 90% of the CFRP failure strain were recorded. Performance of externally bonded reinforcing (EBR) and NMS techniques was compared for strengthening RC beams failing in shear. NMS was much more effective, not only in terms of the increase of the load carrying capacity and deformability at beam failure, but also with respect to the time consuming nature of the corresponding strengthening procedures. To assess the bond behavior of CFRP to concrete, pulloutbending tests were carried out. The influences of bond length and concrete strength on the bond behavior were analyzed.S&P®. Bettor MBT® Portugal. Secil. Nordesfer. Ferseque. Casais. Solusel. VSL. Unibetão (Braga). Cemacom

Nova abordagem no reforço de estruturas com materiais compósitos

Neste trabalho apresentam-se os resultados mais significativos da investigação experimental realizada para avaliar o desempenho de uma técnica de reforço baseada na fixação de laminados de CFRP em ranhuras efectuadas no betão de recobrimento de elementos estruturais. Com esta técnica foram reforçados e ensaiados elementos de pilar e de viga de betão armado com rotura por flexão, e vigas de betão armado com rotura por corte. De modo a caracterizar a ligação betão-adesivo-CFRP procedeu-se à realização de ensaios de aderência

Detoxification of ciprofloxacin in an anaerobic bioprocess supplemented with magnetic carbon nanotubes: contribution of adsorption and biodegradation mechanisms

In anaerobic bioreactors, the electrons produced during the oxidation of organic matter can potentially be used for the biological reduction of pharmaceuticals in wastewaters. Common electron transfer limitations benefit from the acceleration of reactions through utilization of redox mediators (RM). This work explores the potential of carbon nanomaterials (CNM) as RM on the anaerobic removal of ciprofloxacin (CIP). Pristine and tailored carbon nanotubes (CNT) were first tested for chemical reduction of CIP, and pristine CNT was found as the best material, so it was further utilized in biological anaerobic assays with anaerobic granular sludge (GS). In addition, magnetic CNT were prepared and also tested in biological assays, as they are easier to be recovered and reused. In biological tests with CNM, approximately 99% CIP removal was achieved, and the reaction rates increased ?1.5-fold relatively to the control without CNM. In these experiments, CIP adsorption onto GS and CNM was above 90%. Despite, after applying three successive cycles of CIP addition, the catalytic properties of magnetic CNT were maintained while adsorption decreased to 29 ± 3.2%, as the result of CNM overload by CIP. The results suggest the combined occurrence of different mechanisms for CIP removal: adsorption on GS and/or CNM, and biological reduction or oxidation, which can be accelerated by the presence of CNM. After biological treatment with CNM, toxicity towards Vibrio fischeri was evaluated, resulting in ? 46% detoxification of CIP solution, showing the advantages of combining biological treatment with CNM for CIP removal.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020-Programa Operacional Regional do Norte. Ana Rita Silva holds an FCT grant SFRH/BD/131905/2017. Cátia S.N. Braga holds an FCT grant SFRH/BD/132003/2017. This work was also financially supported by: Base Funding-UIDB/50020/2020 of the Associate Laboratory LSRE LCM-funded by national funds through FCT/MCTES (PIDDAC). OSGPS acknowledges FCT fund ing under the Scientific Employment Stimulus-Institutional Call CEECINST/00049/2info:eu-repo/semantics/publishedVersio

Methodology for the development of a taxonomy and toolkit to evaluate health-related habits and lifestyle (eVITAL)

<p>Abstract</p> <p>Background</p> <p>Chronic diseases cause an ever-increasing percentage of morbidity and mortality, but many have modifiable risk factors. Many behaviors that predispose or protect an individual to chronic disease are interrelated, and therefore are best approached using an integrated model of health and the longevity paradigm, using years lived without disability as the endpoint.</p> <p>Findings</p> <p>This study used a 4-phase mixed qualitative design to create a taxonomy and related online toolkit for the evaluation of health-related habits. Core members of a working group conducted a literature review and created a framing document that defined relevant constructs. This document was revised, first by a working group and then by a series of multidisciplinary expert groups. The working group and expert panels also designed a systematic evaluation of health behaviors and risks, which was computerized and evaluated for feasibility. A demonstration study of the toolkit was performed in 11 healthy volunteers.</p> <p>Discussion</p> <p>In this protocol, we used forms of the community intelligence approach, including frame analysis, feasibility, and demonstration, to develop a clinical taxonomy and an online toolkit with standardized procedures for screening and evaluation of multiple domains of health, with a focus on longevity and the goal of integrating the toolkit into routine clinical practice.</p> <p>Trial Registration</p> <p>IMSERSO registry 200700012672</p

A Study of Brain Networks Associated with Swallowing Using Graph-Theoretical Approaches

Functional connectivity between brain regions during swallowing tasks is still not well understood. Understanding these complex interactions is of great interest from both a scientific and a clinical perspective. In this study, functional magnetic resonance imaging (fMRI) was utilized to study brain functional networks during voluntary saliva swallowing in twenty-two adult healthy subjects (all females, 23.1±1.52 years of age). To construct these functional connections, we computed mean partial correlation matrices over ninety brain regions for each participant. Two regions were determined to be functionally connected if their correlation was above a certain threshold. These correlation matrices were then analyzed using graph-theoretical approaches. In particular, we considered several network measures for the whole brain and for swallowing-related brain regions. The results have shown that significant pairwise functional connections were, mostly, either local and intra-hemispheric or symmetrically inter-hemispheric. Furthermore, we showed that all human brain functional network, although varying in some degree, had typical small-world properties as compared to regular networks and random networks. These properties allow information transfer within the network at a relatively high efficiency. Swallowing-related brain regions also had higher values for some of the network measures in comparison to when these measures were calculated for the whole brain. The current results warrant further investigation of graph-theoretical approaches as a potential tool for understanding the neural basis of dysphagia. © 2013 Luan et al

Effects of conductive and non-conductive materials on the activity of a hydrogenotrophic methanogen

Several conductive materials (CM), such as carbon nanotubes (CNT), activated carbon (AC), and magnetite, have been reported to mediate interspecies electron transfer in methanogenic environments. However, CNT also accelerated methane production (MP) of pure cultures of methanogens. We hypothesize that other CM and also non-CM may affect the methanogenic activity of pure cultures. For that purpose, we incubated the hydrogenotrophic methanogen, Methanobacteriun formicicum strain DSM 1535T, with AC, zeolite (Zeo), sand and glass beads (at 0.5 g/L), and followed MP. All materials reduced lag phases preceding the MP, and the time for complete conversion of H2/CO2 to methane. The best results were obtained with Zeo, since total hydrogen conversion occurred in less than 5 days (instead of 8 days as in the control incubated without materials). Approximately 5 days with sand, and 6 days with glass beads and AC, were necessary to achieve the complete conversion. The lag phases with AC were quite short (1 day) when compared with the control assay without materials (5 days). The initial MP (determined during the first 3 days of incubation) was improved 16 times with Zeo and 11 times with AC, when compared with the cultures incubated without materials. The results show that there is not a direct relationship between conductivity and the improvement of methanogenic activity. Other physicochemical properties of the materials might be related with the beneficial effects towards methanogens.info:eu-repo/semantics/publishedVersio

Zeolite stimulates the activity of microbial enrichments converting butyrate to methane

Conductive materials have been tested as a strategy to improve methane production (MP) in anaerobic digestion (AD) processes1,2. The effect of zeolite (0.5 g/L) towards microbial enrichments converting butyrate (10 mmol/L) to methane was investigated and compared with a microbial enrichment in the absence of the material. The enrichments were initiated with granular anaerobic sludge from a brewery WWTP as inoculum. Incubations were carried out under strict anaerobic conditions (at 37 °C) and periodically transferred to fresh medium. The results showed that, after an initial adaptation period (3 transfers), the presence of zeolite significantly accelerated the total conversion of butyrate to methane, since it took approximately 30d with zeolite and around 45d without zeolite. However, both enrichment cultures after extended adaptation (more than 8 transfers) behaved similarly, degrading butyrate in approximately 15d. Nevertheless, zeolite addition to active butyrate enrichment cultures without previous contact with zeolite, slightly accelerated MP, while the highly adapted zeolite-enrichment decreased activity when incubated without zeolite. Thus, the presence of zeolite showed to stimulate the microbial activity enhancing MP from butyrate degradation. This material possess natural ion-exchange properties, absorptive capacity and could function as a support for biomass which makes its application very attractive to AD processes.info:eu-repo/semantics/publishedVersio