A Numerical Solution for the Shape of Fabric-formed Concrete Structures

This paper details a new numerical method for determining the form of a section of flexible, impermeable and inextensible hanging fabric subject to the hydrostatic load imposed by wet concrete. A closed form solution is already known to exist in the form of incomplete elliptic integrals, but this can be difficult to implement in practice. The numerical method presented here was developed by the authors, and the method has been subsequently implemented by researchers investigating the behaviour of fabric-formed concrete beams. It is thought that this method may be of use to other designers and investigators interested in the form of flexible formworks and also of wider interest for the design of flexible scoops or other hydrostatically loaded structures. The method is shown to be applicable to full, part-full and overfull, i.e. surcharged, containers. The method's accuracy is demonstrated by comparison with the predictions of the closed form solution and with reference to the conclusions of previous empirical investigations. Comparison is also made on a graphical basis to a number of reported hydrostatically determined forms, with good agreement being shown. This indicates that the approach has direct application as a form-finding procedure for fabric-formed concrete structures.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.istruc.2016.08.00

Proposal for Defining a Tall Timber Building

In order to talk about ‘tall’ buildings and more particularly ‘tall, timber’ buildings, it is useful to clarify what is meant by a ‘tall’ and a ‘tall, timber’ building. This clarification facilitates both productive discussion of the subject and secures the basis on which meaningful comparisons can be made between buildings using different structural systems and materials. The historic duopoly of steel and concrete as the structural materials of tall building construction is in the process of being broken by the introduction of engineered timber and it is appropriate that this change is reflected in the language of tall building design. The approach adopted in this paper has three parts. Existing definitions and terminology for ‘tall’ buildings are explored. A study is made of the structural systems and materials of existing buildings that use structural timber and have some claim to ‘tallness’. A proposal is made for the clarification and expansion of existing criteria for tall building terminology and definitions to accommodate the use of structural timber in tall building.This is the author accepted manuscript. The final version is available from the American Society of Civil Engineers via http://dx.doi.org/10.1061/(ASCE)ST.1943-541X.000161

Modified push-off testing of an inclined shear plane in reinforced concrete strengthened with CFRP fabric

This study reports the findings of an experimental investigation into the behaviour of an inclined shear plane in reinforced concrete, such as a diagonal crack in the web of a beam, strengthened with externally bonded Carbon Fibre Reinforced Polymer (CFRP) fabric. A modified push-off test of novel geometry was developed for this study. This test generates a diagonal failure plane subject to combined shear and tension. Both unwrapped and wrapped tests were conducted, allowing the load sharing and load displacement behaviour of the reinforced concrete, and the reinforced concrete with externally bonded CFRP fabric, to be investigated. Fully wrapped and U-wrapped CFRP fabric configurations were tested. Results indicate that for the arrangement tested, concrete, steel and CFRP contributions to resistance are not independent, and that effective anchorage lengths given in the UK and US guidance for U-wrapped CFRP may not be adequate in some cases.The authors wish to gratefully acknowledge the financial support of the UK Engineering and Physical Sciences Research Council (EPSRC) through grant EP/I018972/1 . The authors also wish to extend their sincere thanks to Jan Nilsson, Martin Touhey and the staff of the University of Cambridge Structures Research Lab for their invaluable assistance in carrying out the experimental programme reported above.This is the author accepted manuscript. The final version is available at http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29CC.1943-5614.0000623

Relative proximity of chromosome territories influences chromosome exchange partners in radiation-induced chromosome rearrangements in primary human bronchial epithelial cells

Copyright © 2013 The Authors. This article is made available through the Brunel Open Access Publishing Fund. This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-No Derivative Works License, which permits non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited.Copyright © 2013 The Authors. It is well established that chromosomes exist in discrete territories (CTs) in interphase and are positioned in a cell-type specific probabilistic manner. The relative localisation of individual CTs within cell nuclei remains poorly understood, yet many cancers are associated with specific chromosome rearrangements and there is good evidence that relative territorial position influences their frequency of exchange. To examine this further, we characterised the complexity of radiation-induced chromosome exchanges in normal human bronchial epithelial (NHBE) cells by M-FISH analysis of PCC spreads and correlated the exchanges induced with their preferred interphase position, as determined by 1/2-colour 2D-FISH analysis, at the time of irradiation. We found that the frequency and complexity of aberrations induced were reduced in ellipsoid NHBE cells in comparison to previous observations in spherical cells, consistent with aberration complexity being dependent upon the number and proximity of damaged CTs, i.e. lesion proximity. To ask if particular chromosome neighbourhoods could be identified we analysed all radiation-induced pair-wise exchanges using SCHIP (statistics for chromosome interphase positioning) and found that exchanges between chromosomes (1;13), (9;17), (9;18), (12;18) and (16;21) all occurred more often than expected assuming randomness. All of these pairs were also found to be either sharing similar preferred positions in interphase and/or sharing neighbouring territory boundaries. We also analysed a human small cell lung cancer cell line, DMS53, by M-FISH observing the genome to be highly rearranged, yet possessing rearrangements also involving chromosomes (1;13) and (9;17). Our findings show evidence for the occurrence of non-random exchanges that may reflect the territorial organisation of chromosomes in interphase at time of damage and highlight the importance of cellular geometry for the induction of aberrations of varying complexity after exposure to both low and high-LET radiation.Department of Healt

Relationship of structure and stiffness in laminated bamboo composites

Laminated bamboo in structural applications has the potential to change the way buildings are constructed. The fibrous microstructure of bamboo can be modelled as a fibre-reinforced composite. This study compares the results of a fibre volume fraction analysis with previous experimental beam bending results. The link between fibre volume fraction and bending stiffness shows that differences previously attributed to preservation treatment in fact arise due to strip thickness. Composite theory provides a basis for the development of future guidance for laminated bamboo, as validated here. Fibre volume fraction analysis is an effective method for non-destructive evaluation of bamboo beam stiffness

Briefing: Super tall timber – Oakwood Tower

This briefing presents some of the early findings of the super tall timber project, an innovative research and design project exploring the potential of engineered timber as a structural material in the construction of tall buildings. The project brings researchers together with practising engineers and architects in a process that combines design-led research with research-led design in a constructive feedback loop, providing a new model for addressing the fundamental challenges of designing with a new structural material. The first result of this project is a concept design for a 300 m tall timber building sited in London.The authors gratefully acknowledge the financial support of the Engineering and Physical Sciences Research Council under grant EP/M01679X/1

Experimental Investigation of Reinforced Concrete T-Beams Strengthened in Shear with Externally Bonded CFRP Sheets

An experimental investigation was undertaken into the effectiveness of unanchored and anchored externally bonded (EB) U-wrapped carbon fibre reinforced polymer (CFRP) shear strengthening for reinforced concrete T-beams at a range of realistic sizes. The T-beam sizes, geometry and reinforcement were chosen to reflect existing slab-on-beam structures with low levels of transverse steel shear reinforcement. Geometrically similar reinforced concrete T-beams were tested across three sizes ranging from 360 to 720 mm in depth and with different amounts of EB CFRP shear reinforcement. The beams were subjected to three-point bending with a span to depth ratio of 3.5. All the beams failed in diagonal shear. The experimental results indicate significant variability in the capacity of unstrengthened control beams, and a number of these control beams showed greater shear capacity than their EB CFRP strengthened counterparts. Greater thicknesses of CFRP reinforcement did not lead to increased shear capacity compared with lesser thicknesses of unanchored or anchored EB CFRP, but anchored EB CFRP did lead to moderate increases in shear capacity compared to both control and unanchored EB CFRP strengthened beams.The authors gratefully acknowledge the help of the laboratory staff of University of Bath and University of Cambridge. The authors would also like to acknowledge the financial support of: the UK Engineering and Physical Sciences Research Council (under grants EPSRC EP/I018921/1 and EP/I018972/1); the Universities of Bath and Cambridge; and the project partners and sponsors – Parsons Brinckerhoff, Tony Gee and Partners LLP, Arup, Highways England, Concrete Repairs Ltd, LG Mouchel and Partners, The Concrete Society, Fyfe Europe S.A., Fibrwrap UK, Hughes Brothers and Ebor Concrete Ltd.This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by ASCE

What is tall timber? Towards the formal classification of timber as a material of tall building design

The emergence of taller buildings using engineered timber as a structural material raises important questions about the language that is used to describe tall buildings. In the absence of formal definitions it is difficult to make meaningful comparisons between buildings using different materials, structural systems and building forms. Claims to the title of 'tallest timber building' are frequently made and may be subject to dispute. This paper discusses the role of the CTBUH Criteria for Defining and Measuring Tall Buildings in the classification of tall buildings and the challenges to the existing criteria raised by the emergence of engineered timber as a contemporary structural material. The paper highlights the authors' proposal for updating the existing terminology to accommodate the use of timber in the design of tall buildings and details the progress that has been made in moving towards a revision of the CTBUH Criteria to include timber. This progress is significant as it represents a critical step forward in bringing timber engineering into the mainstream discourse of tall building construction and places timber on a level playing field with steel and concrete.Leverhulme Trust, EPSR

Heat transport in insulators from ab initio Green-Kubo theory

The Green-Kubo theory of thermal transport has long be considered incompatible with modern simulation methods based on electronic-structure theory, because it is based on such concepts as energy density and current, which are ill-defined at the quantum-mechanical level. Besides, experience with classical simulations indicates that the estimate of heat-transport coefficients requires analysing molecular trajectories that are more than one order of magnitude longer than deemed feasible using ab initio molecular dynamics. In this paper we report on recent theoretical advances that are allowing one to overcome these two obstacles. First, a general gauge invariance principle has been established, stating that thermal conductivity is insensitive to many details of the microscopic expression for the energy density and current from which it is derived, thus permitting to establish a rigorous expression for the energy flux from Density-Functional Theory, from which the conductivity can be computed in practice. Second, a novel data analysis method based on the statistical theory of time series has been proposed, which allows one to considerably reduce the simulation time required to achieve a target accuracy on the computed conductivity. These concepts are illustrated in detail, starting from a pedagogical introduction to the Green-Kubo theory of linear response and transport, and demonstrated with a few applications done with both classical and quantum-mechanical simulation methods.Comment: 36 pages, 14 figure