Numerical modelling of the punching behaviour of steel fibre reinforced self-compacting concrete flat slabs

Punching shear failure on flat reinforced concrete slabs of residential and commercial buildings is generally avoided by using transversal reinforcement and/or chapiters. The first option requires intense labour, mainly when densely flexural reinforcement exists in the potential punching failure region, with detrimental consequences in terms of costs of this construction solution. The second option has also extra costs due to the necessity of special arrangements of moulds for casting the chapiters. The interference of a chapiter on the flatness of the slab can also be a negative aspect from the architectonic point of view. The use of steel fibre reinforcement can be a solution to avoid both the conventional punching reinforcement and chapiters. Therefore, an experimental program was carried out to assess the potentialities of steel fibre reinforced self-compacting concrete (SFRSCC) for the punching resistance of flat slabs centrically loaded. This experimental program is described, and the main results are presented and analysed. To assess the potentialities of the Reissner-Mindlin FEM-based theory for modelling the behaviour of flat SFRSCC slabs submitted to punching loading configuration, new features were introduced in the out-ofplane shear constitutive law of the SFRSCC. These features are briefly described and the main focus was given on the modelling strategy adopted for simulating the punching tests.Fundação para a Ciência e a Tecnologia (FCT

Numerical simulation of the punching shear behaviour of self-compacting fibre reinforced flat slabs

This paper presents the numerical simulations of the punching behaviour of centrally loaded steel fibre reinforced self-compacting concrete (SFRSCC) flat slabs. Eight half scaled slabs reinforced with different content of hooked-end steel fibres (0, 60, 75 and 90 kg/m3) and concrete strengths of 50 and 70 MPa were tested and numerically modelled. Moreover, a total of 54 three-point bending tests were carried out to assess the post-cracking flexural tensile strength. All the slabs had a relatively high conventional flexural reinforcement in order to promote the occurrence of punching failure mode. Neither of the slabs had any type of specific shear reinforcement rather than the contribution of the steel fibres. The numerical simulations were performed according to the Reissner-Mindlin theory under the finite element method framework. Regarding the classic formulation of the Reissner-Mindlin theory, in order to simulate the progressive damage induced by cracking, the shell element is discretized into layers, being assumed a plane stress state in each layer. The numerical results are, then, compared with the experimental ones and it is possible to notice that they accurately predict the experimental force-deflection relationship. The type of failure observed experimentally was also predicted in the numerical simulations.This work is 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 “SlabSys – HFRC – Flat slabs for multi-storey buildings using hybrid reinforced self-compacting concrete: an innovative structural system” PTDC/ECM/120394/2010

Correlação entre ensaios com câmara termográfica e resistógrafo na avaliação da integridade de vigas antigas de madeira

Este trabalho de investigação pretende dar um contributo no campo das técnicas não destrutivas de inspecção e de diagnóstico de vigas antigas de madeira. Para o efeito, correlacionou-se os resultados obtidos através do uso do resistógrafo e da termografia no estudo de uma viga recolhida num edifício de habitação unifamiliar que foi sujeito a um processo de remodelação. Verificou-se que poderá haver uma cerca correlação entre ensaios. Contudo, também se recomenda a realização de um número mais expressivo de ensaios de amostras para ser possível apresentar uma conclusão mais fidedigna. A relevância desta possível correlação prende-se com o facto de poder haver uma alternância na realização destes ensaios consoante os condicionalismos do cenário de obra

<i>Gaia</i> Data Release 1. Summary of the astrometric, photometric, and survey properties

Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues – a realisation of the Tycho-Gaia Astrometric Solution (TGAS) – and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of ∼3000 Cepheid and RR-Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr−1 for the proper motions. A systematic component of ∼0.3 mas should be added to the parallax uncertainties. For the subset of ∼94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr−1. For the secondary astrometric data set, the typical uncertainty of the positions is ∼10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to ∼0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data

Telomere Length as a Biomarker for Adiposity Changes after a Multidisciplinary Intervention in Overweight/Obese Adolescents: The EVASYON Study

[Context] Telomeres are biomarkers of biological aging. Shorter telomeres have been associated with increased adiposity in adults. However, this relationship remains unclear in children and adolescents. [Objective] To evaluate the association between telomere length (TL) and adiposity markers in overweight/obese adolescents after an intensive program. We hypothesize that greater TL at baseline would predict a better response to a weight loss treatment. Design, Setting, Patients and Intervention The EVASYON is a multidisciplinary treatment program for adolescents with overweight and obesity that is aimed at applying the intervention to all possibly involved areas of the individual, such as dietary habits, physical activity and cognitive and psychological profiles. Seventy-four participants (36 males, 38 females, 12–16 yr) were enrolled in the intervention program: 2 months of an energy-restricted diet and a follow-up period (6 months). [Main Outcome] TL was measured by quantitative real-time polymerase chain reaction at baseline and after 2 months; meanwhile, anthropometric variables were also assessed after 6 months of follow-up. [Results] TL lengthened in participants during the intensive period (+1.9±1.0, p<0.001) being greater in overweight/obese adolescents with the shortest telomeres at baseline (r = −0.962, p<0.001). Multivariable linear regression analysis showed that higher baseline TL significantly predicted a higher decrease in body weight (B = −1.53, p = 0.005; B = −2.25, p = 0.047) and in standard deviation score for body mass index (BMI-SDS) (B = −0.22, p = 0.010; B = −0.47, p = 0.005) after the intensive and extensive period treatment respectively, in boys. [Conclusion] Our study shows that a weight loss intervention is accompanied by a significant increase in TL in overweight/obese adolescents. Moreover, we suggest that initial longer TL could be a potential predictor for a better weight loss response.Research relating to this work was funded by grants from the Health Research Fund from the Carlos III Health Institute from Ministry of Health and Consumption, Fondo de Investigación Sanitaria (FIS; PI051579, PI051080) for the EVASYON project; Línea Especial, Nutrición y Obesidad (University of Navarra); Spanish Ministry of Science and Innovation (MICINN) [SAF2010-20367]; Carlos III Health Institute [Centro de Investigación Biomédica en Red (CIBER) project, CB06/03/1017], and RETICS network. The scholarship to S. García-Calzón from the FPU ‘Formación de Profesorado Universitario’ from the Spanish Ministry is fully acknowledged

Poverty, dirt, infections and non-atopic wheezing in children from a Brazilian urban center

BACKGROUND: The causation of asthma is poorly understood. Risk factors for atopic and non-atopic asthma may be different. This study aimed to analyze the associations between markers of poverty, dirt and infections and wheezing in atopic and non-atopic children. METHODS: 1445 children were recruited from a population-based cohort in Salvador, Brazil. Wheezing was assessed using the ISAAC questionnaire and atopy defined as allergen-specific IgE ≥ 0.70 kU/L. Relevant social factors, environmental exposures and serological markers for childhood infections were investigated as risk factors using multivariate multinomial logistic regression. RESULTS: Common risk factors for wheezing in atopic and non-atopic children, respectively, were parental asthma and respiratory infection in early childhood. No other factor was associated with wheezing in atopic children. Factors associated with wheezing in non-atopics were low maternal educational level (OR 1.49, 95% CI 0.98-2.38), low frequency of room cleaning (OR 2.49, 95% CI 1.27-4.90), presence of rodents in the house (OR 1.48, 95% CI 1.06-2.09), and day care attendance (OR 1.52, 95% CI 1.01-2.29). CONCLUSIONS: Non-atopic wheezing was associated with risk factors indicative of poverty, dirt and infections. Further research is required to more precisely define the mediating exposures and the mechanisms by which they may cause non-atopic wheeze

DNA damage in circulating leukocytes measured with the comet assay may predict the risk of death

The comet assay or single cell gel electrophoresis, is the most common method used to measure strand breaks and a variety of other DNA lesions in human populations. To estimate the risk of overall mortality, mortality by cause, and cancer incidence associated to DNA damage, a cohort of 2,403 healthy individuals (25,978 person-years) screened in 16 laboratories using the comet assay between 1996 and 2016 was followed-up. Kaplan-Meier analysis indicated a worse overall survival in the medium and high tertile of DNA damage (p < 0.001). The effect of DNA damage on survival was modelled according to Cox proportional hazard regression model. The adjusted hazard ratio (HR) was 1.42 (1.06-1.90) for overall mortality, and 1.94 (1.04-3.59) for diseases of the circulatory system in subjects with the highest tertile of DNA damage. The findings of this study provide epidemiological evidence encouraging the implementation of the comet assay in preventive strategies for non-communicable diseases