Filament winding fabrication of FRP reinforcement cages

This project has made progress towards the development of a novel alternative reinforcement technique for concrete structures with complex geometries, which are difficult to reinforce with conventional steel. Fibre-reinforced polymers (FRP) are woven into geometrically appropriate reinforcement cages to provide the required strength exactly where it is needed. Automated fabrication of the reinforcement utilises a modification of the filament winding technique. Being extremely lightweight, the resulting wound- FRP (W-FRP) cages are well suited to automation of the construction process, as they can be delivered ready for casting in optimized concrete elements. This is a key advance in research progress towards achieving minimum embodied energy, optimised, concrete structures. Experimental tests conducted on full-size W-FRP reinforced concrete beams demonstrate the reliability of the solution proposed, showing a new frontier for sustainable and durable reinforced concrete structures

Shear strengthening of continuous reinforced concrete T-beams using deep embedment technique

Despite numerous studies, shear behaviour before or after strengthening is still not fully understood, particularly in continuous concrete structures which are the norm. Upgrading shear resistance is altogether more difficult since Externally Bonded Reinforcement (EBR) or Near Surface Mounted (NSM) techniques do not allow the FRP material to be anchored into the compression zone of the T-beams and they cannot be used in cases where the sides of the beams are inaccessible. An innovative retrofit technique, named Deep Embedment (DE) or Embedded Through Section (ETS) technique involves the insertion of FRP/steel bars upwards into vertical or inclined holes which have been drilled from the soffit of concrete beams. In this way, the tension and compression chords of the beams are directly connected while the bars are bonded to the concrete core through adhesives. With this technique strengthening can be done in cases where the webs are inaccessible. Thus the main focus of this study is to significantly contribute to the current knowledge on the behaviour of Reinforced Concrete continuous T-beamsstrengthened in shear using the DE technique where large shear forces are combined with large negative bending moments. An experimental program consisting of ten two-span continuous T-beams designed to fail in shear wascarried out in order to significantly contribute to the current knowledge on the behaviour of RC continuous Tbeams strengthened in shear using this technique. Therefore, this paper reports on the test results and on their significance in being able to apply this technique on concrete structures by validating them through adequate analytical models

Mechanics of failure in FRP strengthened reinforced concrete in shear

Carbon fibre reinforced polymer (CFRP) composite sheets and bars were used to strengthen reinforced concrete across a known plane to resist shear friction. The uncracked push-off specimens were either externally reinforced with CFRP sheets with a reinforcement ratio of 0.8% and 1.6% or internally with CFRP bars as additional shear reinforcement corresponding to 0.8% reinforcement ratio. Two ratios of internal steel reinforcement were considered representing the nominal stirrup reinforcement according to both historic (0.17%) and current design codes (0.26%). The effects of varying anchorage length of the CFRP on the shear friction capacity of the push-off specimens with externally bonded reinforcement (EBR) were studied through various strengthening schemes. Experimental results showed an increase in shear strength ranging from 23 – 84% compared to the unstrengthened control specimens. Tests with various wrapping schemes showed no evidence that additional shear friction capacity can be developed when beyond a sufficient anchorage length. However, specimens with short anchorage length failed prematurely due to the early debonding of the CFRP. The shear friction strength of the initially uncracked push- off specimens was determined using experimental results combining the shear friction contribution of the individual structural components, extending the currently accepted approach for internal steel reinforcement

Concrete structures using fabric formwork

Using fabric formwork, it is possible to cast architecturally interesting, optimised structures that use up to 40% less concrete than an equivalent strength prismatic section, thereby offering the potential for significant embodied energy savings in new concrete structures. This paper reports on the philosophy of and background to fabric formwork before techniques for the design, optimisation and shape prediction of fabric formed concrete beams are presented. The practicality of construction with non-orthogonal elements is discussed before the results of new structural test data, undertaken at the University of Bath on 4m span ’T’ beam elements formed in reusable fabric moulds, are presented. Potential areas of future development for fabric formwork, including the use of woven advanced composite fabrics as permanent participating formwork and the feasibility of uniform strength prestressed beams, are then discussed The practicality of construction with non-orthogonal elements is discussed before the results of new structural test data, undertaken at the University of Bath on 4m span ‘T’ beam elements formed in reusable fabric moulds, are presented. Potential areas of future development for fabric formwork, including the use of woven advanced composite fabrics as permanent participating formwork and the feasibility of uniform strength prestressed beams, are then discussed

Shear design of circular concrete sections using the eurocode 2 truss model

The introduction of the Eurocodes for concrete design will alter the way that shear is approached for concrete structures. BS EN 1992-1-1 has adopted the variable angle truss model for shear, a more theoretically consistent approach than that used in BS 8110-1. The model is confidently applied to rectangular sections, but its applicability to irregular sections is less clear. In particular, the behaviour of circular concrete sections is not well defined. This paper is intended to satisfy a requirement for design guidance on this topic that has been recognised by key BSI Committees. Using both experimental and theoretical data, the Eurocode variable angle truss model for shear design is assessed and extended to circular columns

Simulation Contact Lenses for AMD Health State Utility Values in NICE Appraisals: A Different Reality

Background/aims: The National Institute for Health and Care Excellence (NICE) has recommended the use of ranibizumab for age-related macular degeneration (AMD) and for diabetic macular oedema (DMO) as part of its health technology appraisal (HTA) process. In the economic evaluations of both interventions, utility values were derived from members of the general public wearing contact lenses with a central opacity that was meant to simulate the blind spot experienced by many patients with advanced retinal disease. This paper tests the validity of the contact lens simulation, and finding it to be invalid, explores the impact on prior economic evaluations. Methods: Visual acuity, contrast sensitivity, and visual fields were assessed with and without simulation lenses in five healthy subjects with normal vision. Results: We identified important differences between the contact lens simulation and vision loss experienced by patients with AMD. The contact lens simulator did not cause the central scotoma which is characteristic of late-stage AMD and which leads to severe difficulty with everyday activities such as reading or recognising faces and objects. The contact lenses instead caused a reduction in retinal illumination experienced by the subjects as a general dimming across the retina. Conclusion: A contact lens with a central opacity does not simulate a central scotoma. The clinical differences between simulated and actual AMD suggests there has been an underestimation of the severity of AMD health states. This brings into question the validity of the economic evaluations of treatments for AMD and DMO used by NICE

Spatiotemporal control of mitotic exit during anaphase by an aurora B-Cdk1 crosstalk

According to the prevailing ‘clock’ model, chromosome decondensation and nuclear envelope reformation when cells exit mitosis are byproducts of Cdk1 inactivation at the metaphase-anaphase transition, controlled by the spindle assembly checkpoint. However, mitotic exit was recently shown to be a function of chromosome separation during anaphase, assisted by a midzone Aurora B phosphorylation gradient-the ‘ruler’ model. Here we found that Cdk1 remains active during anaphase due to ongoing APC/CCdc20- and APC/CCdh1-mediated degradation of B-type Cyclins in Drosophila and human cells. Failure to degrade B-type Cyclins during anaphase prevented mitotic exit in a Cdk1-dependent manner. Cyclin B1-Cdk1 localized at the spindle midzone in an Aurora B-dependent manner, with incompletely separated chromosomes showing the highest Cdk1 activity. Slowing down anaphase chromosome motion delayed Cyclin B1 degradation and mitotic exit in an Aurora B-dependent manner. Thus, a crosstalk between molecular ‘rulers’ and ‘clocks’ licenses mitotic exit only after proper chromosome separation.We thank Eric Griffis, Jean-René Huynh, Claudio Sunkel, Jonathon Pines, Melina Schuh and Christian Lehner for the kind gift of reagents, and Marco Gonzalez-Gaitán for supporting OA during the final stages of this work. LPC is the recipient of a Marie Skłodowska-Curie Action fellowship (grant agreement 746515). EMS holds an FCT Investigator position and his work is supported by Fundac¸ ão para a Ciência e a Tecnologia (PTDC/BEX-BCM/0432/2014). This work was supported by R01GM107026 grant to TJM and a Commonwealth Honors College grant to CMC Confocal and FLIM microscopy data collection was performed in the Light Microscopy Facility and Nikon Center of Excellence at the Institute for Applied Life Sciences, University of Massachusetts Amherst with support from the Massachusetts Life Science Center. Work in the HM lab is supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 681443) and FLAD Life Science 2020

Primary vs. secondary H-atom abstraction in the Cl-atom reaction with n-pentane

Velocity map imaging measurements and quasi-classical trajectory calculations on a newly developed, global potential energy surface combine to reveal the detailed mechanisms of reaction of Cl atoms with n-pentane.</p

Flexible formwork technologies – a state of the art review

Concrete is our most widely used construction material. Worldwide consumption of cement, the strength-giving component of concrete, is estimated at 4.10 Gt per year, rising from 2.22 Gt just ten years ago [1]. This rate of consumption means that cement manufacture alone is estimated to account for 5.2 % of global carbon dioxide emissions [2].Concrete offers the opportunity to economically create structures of almost any geometry. Yet its unique fluidity is seldom capitalised upon, with concrete instead being cast into rigid, flat moulds to create unoptimised geometries that result in high material use structures with large carbon footprints. This paper will explore flexible formwork construction technologies which embrace the fluidity of concrete to facilitate the practical construction of concrete structures with complex and efficient geometries. This paper presents the current state of the art in flexible formwork technology, highlighting practical uses, research challenges and new opportunities

X-ray Absorption and Reflection in Active Galactic Nuclei

X-ray spectroscopy offers an opportunity to study the complex mixture of emitting and absorbing components in the circumnuclear regions of active galactic nuclei, and to learn about the accretion process that fuels AGN and the feedback of material to their host galaxies. We describe the spectral signatures that may be studied and review the X-ray spectra and spectral variability of active galaxies, concentrating on progress from recent Chandra, XMM-Newton and Suzaku data for local type 1 AGN. We describe the evidence for absorption covering a wide range of column densities, ionization and dynamics, and discuss the growing evidence for partial-covering absorption from data at energies > 10 keV. Such absorption can also explain the observed X-ray spectral curvature and variability in AGN at lower energies and is likely an important factor in shaping the observed properties of this class of source. Consideration of self-consistent models for local AGN indicates that X-ray spectra likely comprise a combination of absorption and reflection effects from material originating within a few light days of the black hole as well as on larger scales. It is likely that AGN X-ray spectra may be strongly affected by the presence of disk-wind outflows that are expected in systems with high accretion rates, and we describe models that attempt to predict the effects of radiative transfer through such winds, and discuss the prospects for new data to test and address these ideas.Comment: Accepted for publication in the Astronomy and Astrophysics Review. 58 pages, 9 figures. V2 has fixed an error in footnote