An advanced polymer composite and concrete slab system

This paper reports on an investigation into the feasibility of a structural slab system comprising of a sheet of carbon fibre reinforced polymer (CFRP) in tension and concrete in compression. The CFRP serves as permanent formwork as well as tension reinforcement. It was found that the slab system performed satisfactorily at ultimate and serviceability limit states. A design for a slab for use in a typical building is presented

Lateral stress profiles on integral bridge abutments

Integral bridges have become established as a viable structural form in many countries for reducing maintenance liability and increasing structure robustness. The advent of new design guidance associated with the Eurocodes provides an opportunity to review the design of these structures. Research indicates that peak stresses due to bridge expansion continually increase with cycles and in theory may reach fully passive. However, this may not happen in practice during a bridge's life. A numerical model has been developed and calibrated against test data, enabling predictions of the development of lateral stresses acting on a full-height frame integral abutment during its life, both in terms of magnitude and distribution down the wall. Design guidance is shown to be appropriate for bridges up to 60 m in length, but to be unconservative for longer bridges. The effect of applying daily cycles of movement rather than just annual cycles has also been investigated

Integral bridges? Development of a constitutive soil model for soil structure interaction

Traditionally, engineers have used bearings and expansion joints to accommodate bridge expansion and contraction caused by daily and seasonal temperature fluctuations. Studies carried out in the late 1980s showed durability problems can be associated with bearings and expansion joints Wallbank, 1989. Since the mid twentieth century Integral Bridges with no expansion joints or bearings have been used. Deck expansion and contraction is accommodated by movement of the abutments into the retained fill. This eliminates the problem of durability but the movement of the abutments has been thought to cause a build up of horizontal pressures, particularly in the case of full height abutments. In the United Kingdom BA42/96 Highways Agency, 2000 was issued and gave guidance on the soil pressures that should be adopted in design. The validity of the work on which the code of practice was based is a subject of continued debate by both researchers and practicing engineers. For this reason Integral Bridges have been used much less widely than conventional bridges. As part of a strategy by the University of Southampton to further investigate the occuring soil pressures, Xu 2005 carried out radial controlled triaxial tests of granular material under cyclic loading. The applied strain and stress path used represented that typically experienced by an element of retained material behind an integral bridge abutment. This was the first time that the fundamental behaviour had been investigated in this way. The further research discussed in this paper builds upon this by use of numerical modelling. The fundamental behaviour of granular material under this particular loading could not be represented by any available constitutive model and therefore a new model was be developed based on this behaviour. The basis of the model and initial validation process are discussed. The first stage of the validation process was implementation in a commercially available spreadsheet package. This was then used to develop a model in the Finite Difference Method package FLAC. Once this was implemented, the triaxial tests were modelled and the results compared to experimental data

Modelling granular soil to predict pressures on integral bridge abutments

Presented here is a granular soil model created to investigate the soil pressures which develop behind integral bridge abutments. The problem is introduced along with a brief summary of the fundamental behaviour, the model produced, and the initial validation. The paper looks at the initial outcome of the final validation procedure where experimental behaviour of an abutment is compared to the modelled behaviour, and the influence of the Young's modulus profile applied is investigated. The results show that the model behaves as expected producing lateral stresses close to those measured experimentally. Comparisons show that the Young's modulus profile adopted influences the resultant lateral stresses sufficiently to warrant further investigation

Hot Tops for STeel Ingots - Their Developments as Influenced by Solidification Patterns

This paper is concerned with hot tops for steel ingots, an area in which Foseco has been actively involved for many years. After defining the need for hot tops, the histo-rical devleopment is reviewed, highlighting the major steps taken in the development of the two hot top compon-ents - sideliner and top cover, in particular the impact made by the introduction of lightweight expandable PROFAX @ side-liners and succesive generations of anti-piping compounds. It next examines current developments, in particular superlightweight exothermic sideliners, and anti-piping is a review of the ancillary testing techn-iques including a computer model for predicting ingot solidification profiles. Finally the future course of hot topping practice is considered highlighting those areas in which further developments are anticipated

Cotton Irrigation in the Lower Rio Grande Valley.

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New results from the NA57 experiment

We report results from the experiment NA57 at CERN SPS on hyperon production at midrapidity in Pb-Pb collisions at 158 $A$ GeV/$c$ and 40 $A$ GeV/$c$. $\Lambda$, $\Xi$ and $\Omega$ yields are compared with those from the STAR experiment at the higher energy of the BNL RHIC. $\Lambda$, $\Xi$, $\Omega$\ and preliminary $K_S^0$ transverse mass spectra are presented and interpreted within the framework of a hydro-dynamical blast wave model.Comment: 8 pages, 3 figures, contribution to the proceedings of The XXXVIIIth Rencontres de Moriond "QCD and High Energy Hadronic Interactions

Expansion dynamics of Pb-Pb collisions at 40 A GeV/c viewed by negatively charged hadrons

In this paper we present results on transverse mass spectra and Hanbury-Brown and Twiss correlation functions of negatively charged hadrons, which are expected to be mostly negative pions, measured in Pb-Pb collisions at 40 A GeV/c beam momentum. Based on these data, the collision dynamics and the space-time extent of the system at the thermal freeze-out are studied over a centrality range corresponding to the most central 53% of the Pb--Pb inelastic cross section. Comparisons with freeze-out conditions of strange particles and HBT results from other experiments are discussed.Comment: 29 pages, 18 figure

Strangeness enhancements at central rapidity in 40 A GeV/c Pb-Pb collisions

Results are presented on neutral kaon, hyperon and antihyperon production in Pb-Pb and p-Be interactions at 40 GeV/c per nucleon. The enhancement pattern follows the same hierarchy as seen in the higher energy data - the enhancement increases with the strangeness content of the hyperons and with the centrality of collision. The centrality dependence of the Pb-Pb yields and enhancements is steeper at 40 than at 158 A GeV/c. The energy dependence of strangeness enhancements at mid-rapidity is discussed.Comment: 15 pages, 10 figures and 3 tables. Presented at International Conference on Strangeness in Quark Matter (SQM2009), Buzios, Rio de Janeiro, Brazil, 27 Sept - 2 Oct 2009. Submitted to J.Phys.G: Nucl.Part.Phys, one reference adde