Distributed fiber optic sensors for monitoring reinforced concrete piles using Brillouin scattering

In this paper we report on advances made in the installation and use of distributed fiber optic sensors to monitor reinforced concrete piles subjected to static load tests. Eight concrete test piles, at three construction sites in London, have recently been instrumented with embedded DFOS. The Brillouin optical time domain reflectometry (BOTDR) technique was used to measure the changes in internal strain and temperature of the piles, during concrete curing and during load testing. These data were used to assess the quality of the pile and derive the load capacity parameters to be used in the foundation design of tall buildings which are to be erected on these sites. The measurements obtained from the DFOS system agreed well with the measurements taken simultaneously using conventional point sensors embedded in the piles. Whereas the conventional sensors only provided measurements at a small number of locations within the piles, the DFOS system made it possible to record the complete strain / temperature profiles along the length of the piles.The authors would like to acknowledge the contribution of (listed in alphabetical order): Hyungjoon Seo, Jason Shardelow, Peter Knott, Yi Rui and Zili Li from CSIC; Duncan Nicholson, Landi Proctor, Stuart Pennington and Vivien Kwan from Ove Arup & Partners Ltd.This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by SPIE

Monitoring the axial displacement of a high-rise building under construction using embedded distributed fibre optic sensors

The floor-to-floor axial shortening of vertical load-bearing elements is an important factor in the design and construction of high-rise buildings. Contractors need to allow for the expected final compression of columns and walls due to superimposed load, concrete creep and shrinkage, particularly when installing finishes and partitions in lower floors, while the building has not yet been completed. An added complication arises from the differential shortening between elements of different stiffness. This axial shortening is predicted by designers using empirical models, in advance of construction. However, in practice, the shortening at every level cannot be measured continuously using traditional surveying measurement techniques during construction. Therefore, a monitoring system using distributed fibre optic sensors (DFOS) measuring strain and temperature, is being installed during the construction of Principal Tower, a 50-storey reinforced concrete building in London. DFOS sensors are being embedded inside two columns and two walls as the construction progresses. Using the strain and temperature data acquired from this system, the axial deformation relative to the ground level can be calculated along the whole height of the completed elements, at any time during the construction. Thus, the engineers and contractors are able to verify their predictions and adjust their assumptions if necessary. A selection of the data acquired during the construction of the first 17 levels of the building is presented. These data have shown that the amount of shortening experienced by a member is influenced by the member’s stiffness and size. The monitoring data have also revealed that thermal movement has a significant effect on the overall axial displacement of the building

Monitoring bridge degradation using dynamic strain, acoustic emission and environmental data

This paper studies the long term structural behaviour of a Victorian railway viaduct under train loading and temperature variation. A multi-sensing, self-sustaining and remotely controlled data acquisition system combines fibre Bragg grating strain sensors with acoustic emission sensors for the study of both global dynamic deformation and local masonry deterioration. A statistical analysis of fibre Bragg grating signals reveals regions with permanent change in the dynamic deformation of the bridge over the last two years, whereas in other locations the deformation follows a seasonal cyclic pattern. In order to decouple changes in structural behaviour due to real mechanical damage from normal seasonal effect, the paper studies the ambient temperature effect on the dynamic deformation of the bridge, showing a clear linear dependence. In particular, when temperature increases, the dynamic strain due to train loading decreases uniformly in the longitudinal direction. In the transverse direction, where the thermal expansion is not constrained, the decrease is smaller. Decoupling damage from normal seasonal effect is of critical importance for the development of reliable early warning structural alert systems for infrastructure networks. The paper further studies local masonry deterioration at four critical location by combining data from the two sensing technologies: fibre optic and acoustic emission sensors.This work is being funded by the Lloyd’s Register Foundation, EPSRC and Innovate UK through the Data-Centric Engineering programme of the Alan Turing Institute and through the Cambridge Centre for Smart Infrastructure and Construction. Funding for the monitoring installation was provided by EPSRC under the Ref. EP/N021614/1 grant and by Innovate UK under the Ref. 920035 grant

Distributed fibre optic sensors for measuring strain and temperature of cast-in-situ concrete test piles

In this paper we present the use of distributed fibre optic sensor (DFOS) technology to measure the temperature and strain of reinforced concrete test piles during construction and during static load tests. Eight test piles were recently instrumented with DFOS, on three construction sites in London, by the Cambridge Centre for Smart Infrastructure and Construction (CSIC), in collaboration with Ove Arup & Partners Ltd. The concrete curing temperature profiles of the piles were used to detect the presence of significant defects in the piles. The load test strain profiles along the length of the piles were used to determine the load capacity of the piles and estimate the design parameters of the various soil strata, as well as the internal relative displacement of the piles under various loads. Being distributed in nature, DFOS give a much more detailed picture of the performance of a test pile, as compared to traditional embedded point sensors, such as vibrating wire strain gauges and extensometers. This is demonstrated with a sample of data obtained from one of the instrumented test piles.This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by ICE Publishing

Exposure to antibiotics and neurodevelopmental disorders: could probiotics modulate the gut–brain axis?

In order to develop properly, the brain requires the intricate interconnection of genetic factors and pre-and postnatal environmental events. The gut–brain axis has recently raised considerable interest for its involvement in regulating the development and functioning of the brain. Consequently, alterations in the gut microbiota composition, due to antibiotic administration, could favor the onset of neurodevelopmental disorders. Literature data suggest that the modulation of gut microbiota is often altered in individuals affected by neurodevelopmental disorders. It has been shown in animal studies that metabolites released by an imbalanced gut–brain axis, leads to alterations in brain function and deficits in social behavior. Here, we report the potential effects of antibiotic administration, before and after birth, in relation to the risk of developing neurodevelopmental disorders. We also review the potential role of probiotics in treating gastrointestinal disorders associated with gut dysbiosis after antibiotic administration, and their possible effect in ameliorating neurodevelopmental disorder symptoms

Distributed fibre optic sensor system to measure the progressive axial shortening of a high-rise building during construction

A novel approach is being used to measure the progressive axial shortening of key structural elements of Principal Tower, a 50-storey reinforced concrete building in London, as it is being built. Distributed fibre optic sensor (DFOS) cables are embedded inside two columns and two core walls, from which the axial strain profile can be measured along the whole height of the constructed elements. Measurements are being taken regularly throughout the construction process, making it possible to observe the change in strain, and thus the axial shortening, within these elements, at any stage of the construction. This helps the design engineers and contractor verify the predicted differential shortening and adjust the column height presets if necessary. The purpose of this paper is to describe the monitoring system and to present initial data recorded from the first five levels of the building.This research has been made possible through funding under EPSRC grant EP/N021614/1 and Innovate UK grant 920035, as well as funding by WSP, Multiplex Construction and Careys

Design and Data Modelling of Fibre Optic Systems to Monitor Reinforced Concrete Structural Elements

Structural monitoring of built assets, performed to ensure safety, usability, and to better understand the assets’ structural behaviour, is becoming common practice. One method to monitor structural behaviour is to use fibre optic systems to measure temperature and strain in structural elements. Fibre optic systems are relatively inexpensive, easy to install, versatile, and widely applicable. However, all the data acquired by monitoring systems are meaningless if they lack context within the built asset, and they are of little use if they cannot be appropriately exchanged and visualised. This paper presents an extension to the IFC data model standard for structural monitoring systems. The extension allows (1) to model structural monitoring systems, (2) to store and retrieve acquired data, and (3) to visualise the data directly on the BIM model. The James Dyson Building at the University of Cambridge is used as a case study, in which selected reinforced concrete columns, beams, and slabs have been instrumented with two types of fibre optic sensors. The case study demonstrates that the extension is able to fully describe the fibre optic monitoring system and that it can aid in its design, deployment, and further operation.The authors would like to acknowledge funding from the UK Engineering and Physical Sciences Research Council (EPSRC) and Innovate UK. This research was carried out under EPSRC grant no. EP/I019308/1. Acknowledgements also go to several people who contributed to, or facilitated the fibre optic sensor installations in the James Dyson Building: Cedric Kechavarzi, David Rodenas Herráiz, Jason Shardelow, Jules Birks, Pasquale Ponterosso and Peter Knott from CSIC; Greg Smith and Toby Lucas from Morgan Sindall.This is the author accepted manuscript. The final version is available from American Society of Civil Engineers via https://doi.org/10.1061/9780784479827.22

Current exposure of Italian women of reproductive age to PFOS and PFOA: a human biomonitoring study

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) concentrations were determined in serum samples collected in 2011-2012 from 549 nulliparous Italian women of reproductive age who resided in six different Italian Regions. Assessment of exposure to perfluorinated compounds was part of a large human biomonitoring study (Project Life Plus "Womenbiopop") that aimed at examining the exposure of women of reproductive age to priority organic pollutants. The median concentrations of PFOS and PFOA were 2.43, and 1.55ngg-1, respectively. Significant differences in the concentrations of both compounds were observed among the six Regions. Women from central Italy had the highest levels of both compounds, followed by women from northern Italy, and southern Italy. No differences in the PFOS concentrations were found between women from urban/industrial areas and women from rural areas, whereas the levels of PFOA were significantly higher in women residing in urban/industrial areas than in women residing in rural areas. Taken together, the observed concentrations confirm that the overall exposure of the Italian population is among the lowest observed in industrialized countries. A downward temporal trend in exposure was observed for both compounds when comparing the results from the present study with those assessed in a study conducted in 2008

Efectos de la reducción de la densidad de siembra en soja

La densidad óptima está sujeta a las condiciones ambientales y edáficas de cada zona. La variación de la cantidad de plantas afecta la capacidad de crecimiento individual debido la competencia en la línea de siembra. Sin embargo, el efecto en el rendimiento no es lineal, dado que los cambios en la disponibilidad de recursos estimulan mecanismos de compensación. En el caso de la Provincia de Entre Ríos la presencia de suelos vertisoles con elevado contenido de arcillas restringe el crecimiento de los cultivos. Con el objetivo de determinar la posibilidad de lograr altos rendimientos con densidades de siembra inferiores a las utilizadas en los planteos agrícolas actuales y determinar los mecanismos de compensación, se realizaron 4 ensayos durante 2013-2016 en lotes con suelos de textura arcillosa donde se utilizaron cultivares de grupo de madurez V y VI con densidades de 3 a 40 plantas m-2. Las menores densidades de 10 y 15 plantas m-2 presentaron diferencias en la intercepción de radiación en el inicio de llenado de granos. Se hallaron diferencias en el número de granos entre las densidades. Sin embargo, este componente presentó poca variación con una disminución del 15-32% al reducir en 61-80% el stand de plantas. El número de granos fue el componente que explicó las diferencias de rendimiento; A bajas densidades se observó mayor generación de nudos en las ramificaciones y además una mayor capacidad de fijar granos por planta. El peso de granos no fue afectado por la variación en la densidad. Esto permitió determinar que en estos cultivares de GM VI el rendimiento relativo del 95% se logra con densidades de 15-20 pl m-2. En los cultivares de GM V este umbral se encontraría en las 25 pl m-2, donde por debajo de este número de plantas el rendimiento se deprime