Structural behaviour of hybrid elements with Advanced Cementitious Materials (HPFRCC)

Advanced Cementitious Materials such as HPFRCC are well adapted for durable repair and strengthening of concrete structures. Experimental and numerical investigations have been conducted to study the behavior of hybrid structural elements consisting of HPFRCC and ordinary concrete. The behavior at service state as well as at ultimate limit state of the beams reinforced with HPFRCC was comparable or better than the behavior of the beams reinforced with ordinary reinforced concrete. The sensitivity of numerical models for hardening materials such as HPFRCC was demonstrated

Evaluation of UHPFRC activation energy using empirical models

The influence of thermal curing on the evolution of the material properties and the UHPFRC behaviour was investigated. Tests results showed a beneficial effect of a high temperature curing on the early age material properties due to the thermo-activation effect on the hydration process. However, an inverse effect was observed at long-term. In our study, activation energy of UHPFRC was evaluated from experimental data by means of empirical models. The traditional maturity-function based on Arrhenius law, generally used to describe thermally activated physical or chemical processes, was used to predict the evolution of the UHPFRC autogenous shrinkage and to validate the applicability of this concept for such cement-based materials. Results showed that the concept based on Arrhenius law could describe correctly temperature effects on UHPFRC for temperature lower than 30°

UHPFRC tensile creep at early age

Ultra high performance fibre reinforced concrete (UHPFRC) early age viscoelastic behaviour under tension was investigated. The tests results showed a high creep potential due to the high volume paste (88%). This result is of major importance because the viscoelastic properties contribute to mitigating the high early age stresses generated under restrained shrinkage. This beneficial effect was reflected by the increased linear-relationship between tensile creep and shrinkage. As expected, UHPFRC tensile creep behaviour was also sensitive to the loading level. Above 35% of the tensile strength at the loading age, the material exhibited viscoplastic behaviour. A Maxwell chain model was applied to predict the early age UHPFRC tensile creep and confirms the induced non-linear respons

Christian Menn's recent bridge designs - Reducing structural elements to the simplest solution

The conceptual designs by Christian Menn of four landmark bridges are presented: 1) a 350-m span cable-stayed bridge with jointless deck girder, 2) a cable-stayed bridge with a single “spindle-shaped” pylon, 3) a bridge with an arch reaching high above the deck (both carrying a horizontally curved deck girder), and 4) a cable stayed bridge with three pylons monolithically connected to the deck girder. All of the original bridge designs are driven by the aim to optimize the flow of forces with the objective to reduce structural elements and their dimensions to a minimum. The four bridges express technical efficiency by slenderness and transparency and emphasize the importance of understanding the functioning of the structural systems. A sound engineering concept is thus the solid basis for a far- reaching aesthetic quality and for the conceptual design of simple but elegant structures that offer a great crossing experience while respecting the functional requirements and providing technical performance

Rational approach for the management of a medium size bridge stock

Infrastructure managers of medium size bridge stocks are being faced with the task of approximating short, mid to long term financial needs for their infrastructure. This task is particularly demanding due to the lack of relevant information, in particular in forecasting bridge condition and intervention costs. It can, therefore, be beneficial to make cost estimations based on structure types and present condition evaluation. In this article a rational approach for the management of the medium size bridge stock including 654 bridges of a regional road network is presented. The basic methodology is given and it is described how this methodology is adopted considering the available information (data base) on the bridge stock on the structures level. The use of age equivalents is suggested to describe bridge condition and to link directly intervention cost to conditio

Fracture of mass concreete under simulated seismic action

The numerical simulation of concrete dams subject to earthquake loading requires realistic material laws which take into account material properties as effected by seismic action. Experiments under simulated seismic action were performed to examine the effect of rapid compressive loading on the fracture properties of mass concrete at high tensile deformation rates. Loading histories, representing typical seismic action, were applied to the specimens. Fracture properties have been investigated by two types of tests : - Uniaxial tensile tests were performed to study the ascending stress against strain curve (up to tensile strength) to describe continuous material under tensile stresses; and, - wedge splitting tests were conducted to investigate tensile softening properties and cracking of mass concrete. The test results showed that the effect of high deformation rates and loading histories must be considered in the seismic analysis of dams. The tensile strength and the specific fracture energy showed a high rate sensitivity. Compressive pre-loading led to some damage of the concrete and a significant decrease in the values of fracture properties. A procedure for the development of material laws, based on these results, is proposed

Hospital discharge: What are the problems, information needs and objectives of community pharmacists? A mixed method approach

After hospital discharge, community pharmacists are often the first health care professionals the discharged patient encounters. They reconcile and dispense prescribed medicines and provide pharmaceutical care. Compared to the roles of general practitioners, the pharmacists' needs to perform these tasks are not well known.; This study aims to a) Identify community pharmacists' current problems and roles at hospital discharge, b) Assess their information needs, specifically the availability and usefulness of information, and c) Gain insight into pharmacists' objectives and ideas for discharge optimisation.; A focus group was conducted with a sample of six community pharmacists from different Swiss regions. Based on these qualitative results, a nationwide online-questionnaire was sent to 1348 Swiss pharmacies.; The focus group participants were concerned about their extensive workload with discharge prescriptions and about gaps in therapy. They emphasised the importance of more extensive information transfer. This applied especially to medication changes, unclear prescriptions, and information about a patient's care. Participants identified treatment continuity as a main objective when it comes to discharge optimisation. There were 194 questionnaires returned (response rate 14.4%). The majority of respondents reported to fulfil their role as defined by the Joint-FIP/WHO Guideline on Good Pharmacy Practice (rather) badly. They reported many unavailable but useful information items, like therapy changes, allergies, specifications for "off-label" medication use or contact information. Information should be delivered in a structured way, but no clear preference for one particular transfer method was found. Pharmacists requested this information in order to improve treatment continuity and patient safety, and to be able to provide better pharmaceutical care services.; Surveyed Swiss community pharmacists rarely receive sufficient information along with discharge prescriptions, although it would be needed for medication reconciliation. According to the pharmacist's opinions, appropriate pharmaceutical care is therefore impeded

Mass enhancement, correlations, and strong coupling superconductivity in the beta-pyrochlore KOs2O6

To assess electron correlation and electron-phonon coupling in the recently discovered beta-pyrochlores KOs2O6 and RbOs2O6, we have performed specific heat measurements in magnetic fields up to 14 T. We present data from high quality single crystalline KOs2O6, showing that KOs2O6 is a strong coupling superconductor with a coupling parameter lambda_ep \approx 1.0 to 1.6 (RbOs2O6: lambda_ep \approx 1). The estimated Sommerfeld coefficient of KOs2O6, gamma=76 to 110 mJ/(mol K^2), is twice that of RbOs2O6 [gamma=44 mJ/(mol K^2)]. Using strong-coupling corrections, we extract useful thermodynamic parameters of KOs2O6. Quantifying lambda_ep allows us to determine the mass enhancement over the calculated band electronic density of states. A significant contribution in addition to the electron-phonon term of lambda_c=1.7 to 4.3 is deduced. In an effort to understand the origin of the enhancement mechanism, we also investigate an unusual energetically low-lying phonon. There are three phonon modes per RbOs2O6, suggestive of the phonon source being the rattling motion of the alkali ion. This dynamic instability of the alkali ions causes large scattering of the charge carriers which shows up in an unusual temperature dependence of the electrical resistivity.Comment: Accepted for publication in PR