Fatigue assessment for deck plates in orthotropic bridge decks

Since the 1960s, orthotropic deck plates of highway bridges have been built with large cold-formed trapezoidal stiffeners supporting a deck plate with a thickness of approx. 12 mm. The maximum cross-beam spacing is approx. 4 m. A number of these bridge decks in The Netherlands suffer from fatigue cracks in the deck plate. First cracks have been observed after about 30 years in service. In one particular movable bridge, the cracks were found after only seven years. In many other countries, this type of crack has not yet been observed. This article provides a fatigue assessment procedure for deck plates. The procedure is calibrated with the conditions and observations in The Netherlands. It gives a fatigue life prediction and takes account of inspection results quantitatively. Although aspects such as the type and thickness of the surface finishes and the traffic load may vary between countries, the principles of the assessment procedure in this article are generally applicable and can be used to identify reasons for differences in fatigue life and to develop strategies for increasing the life

Structural Glass Beams with Embedded Glass Fibre Reinforcement

This paper investigates the possibilities of pultruded glass fibre rods as embeddedreinforcement in SentryGlas (SG) laminated glass beams. To do so, a series of pullouttests, to investigate the bond strength of the rods to the laminate, and a series ofbeam tests, to investigate the post-breakage response of the beams, have beenperformed. Both test series have been conducted for round E-glass fibre rods andflat S-glass fibre rods. The pull-out tests showed superior pull-out strength of theflat rods, due to their large bond area. Furthermore, the beam tests showed superiorpost-breakage performance of the beams with the flat rods, due to higher strengthand stiffness of the S-glass fibres. Overall, it is concluded that embedding glassfibre reinforcement in a SG-laminated glass beam is a very promising concept

Optimization, evaluation, and comparison of standard algorithms for image reconstruction with the VIP-PET

A novel positron emission tomography (PET) scanner design based on a room-temperature pixelated CdTe solid-state detector is being developed within the framework of the Voxel Imaging PET (VIP) Pathfinder project []. The simulation results show a great potential of the VIP to produce high-resolution images even in extremely challenging conditions such as the screening of a human head []. With unprecedented high channel density (450 channels/cm 3) image reconstruction is a challenge. Therefore optimization is needed to find the best algorithm in order to exploit correctly the promising detector potential. The following reconstruction algorithms are evaluated: 2-D Filtered Backprojection (FBP), Ordered Subset Expectation Maximization (OSEM), List-Mode OSEM (LM-OSEM), and the Origin Ensemble (OE) algorithm. The evaluation is based on the comparison of a true image phantom with a set of reconstructed images obtained by each algorithm. This is achieved by calculation of image quality merit parameters such as the bias, the variance and the mean square error (MSE). A systematic optimization of each algorithm is performed by varying the reconstruction parameters, such as the cutoff frequency of the noise filters and the number of iterations. The region of interest (ROI) analysis of the reconstructed phantom is also performed for each algorithm and the results are compared. Additionally, the performance of the image reconstruction methods is compared by calculating the modulation transfer function (MTF). The reconstruction time is also taken into account to choose the optimal algorithm. The analysis is based on GAMOS [] simulation including the expected CdTe and electronic specifics

Simulation of charge transport in pixelated CdTe

The Voxel Imaging PET (VIP) Pathfinder project intends to show the advantages of using pixelated semiconductor technology for nuclear medicine applications to achieve an improved image reconstruction without efficiency loss. It proposes designs for Positron Emission Tomography (PET), Positron Emission Mammography (PEM) and Compton gamma camera detectors with a large number of signal channels (of the order of 10 6). The design is based on the use of a pixelated CdTe Schottky detector to have optimal energy and spatial resolution. An individual read-out channel is dedicated for each detector voxel of size 1 × 1 × 2 mm 3 using an application-specific integrated circuit (ASIC) which the VIP project has designed, developed and is currently evaluating experimentally. The behaviour of the signal charge carriers in CdTe should be well understood because it has an impact on the performance of the readout channels. For this purpose the Finite Element Method (FEM) Multiphysics COMSOL software package has been used to simulate the behaviour of signal charge carriers in CdTe and extract values for the expected charge sharing depending on the impact point and bias voltage. The results on charge sharing obtained with COMSOL are combined with GAMOS, a Geant based particle tracking Monte Carlo software package, to get a full evaluation of the amount of charge sharing in pixelated CdTe for different gamma impact points

Assessment of Existing Steel Structures - Recommendations for Estimation of the Remaining Fatigue Life

Due to the demand for freight volume on rail and road, traffic has increased significantly in the past years leading to an increasing number of heavy vehicles in the traffic flows and greater exploitation of their loading capacities. Because of environmental considerations there is also a tendency to further enhance the admissible loads in the design of new heavy vehicles (e.g. by increasing axle loads or using road trains). This all may affect the safety, serviceability and durability of existing bridges. Bridge authorities are therefore interested in agreed methods to assess the safety and durability of existing bridges and to make appropriate provisions for more refined maintenance methods, possible restriction of traffic, bridge-rehabilitation or substitution of old bridges by new ones where necessary. For steel bridges including the old riveted ones there are numerous approaches to such assessments, partly standardized by national codes or recommendations. In the light of the development of the European single market for construction works and engineering services there is thus a need to harmonize them and to develop agreed European technical recommendations for the safety and durability assessment of existing structures. These recommendations should follow the principles and application rules in the Eurocodes and provide a scheme with different levels of analysis: a basic level with general methods and further levels with higher sophistication that call for specific expertise. This technical report on ¿Recommendations for the estimation of remaining fatigue life¿ supported by the ECCS could be used as a basis for harmonizing National procedures and for the further evolution of the Eurocodes.JRC.G.5-European laboratory for structural assessmen

Performance of the Electromagnetic Calorimeter of the HERMES Experiment

The performance of the electromagnetic calorimeter of the HERMES experiment is described. The calorimeter consists of 840 radiation resistant F101 lead-glass counters. The response to positrons up to 27.5 GeV, the comparison between the measured energy and the momentum reconstructed from tracking, long-term stability, hadron rejection and neutral meson invariant mass reconstruction are shown.Comment: 22 pages, 13 figures, LaTeX, accepted by NI

Measurement of the Stray Light in the Advanced Virgo Input Mode Cleaner Cavity using an instrumented baffle

A new instrumented baffle was installed in Spring 2021 at Virgo surrounding the suspended mirror in the input mode cleaner triangular cavity. It serves as a demonstrator of the technology designed to instrument the baffles in the main arms in the near future. We present, for the first time, results on the measured scattered light distribution inside the cavity as determined by the new device using data collected between May and July 2021, with Virgo in commissioning phase and operating with an input laser power in the cavity of 28.5~W. The sensitivity of the baffle is discussed and the data is compared to scattered light simulations.Comment: 4 pages, 5 figures, 1 tabl

Measurement of the Proton Spin Structure Function g1p with a Pure Hydrogen Target

A measurement of the proton spin structure function g1p(x,Q^2) in deep-inelastic scattering is presented. The data were taken with the 27.6 GeV longitudinally polarised positron beam at HERA incident on a longitudinally polarised pure hydrogen gas target internal to the storage ring. The kinematic range is 0.021<x<0.85 and 0.8 GeV^2<Q^2<20 GeV^2. The integral Int_{0.021}^{0.85} g1p(x)dx evaluated at Q0^2 of 2.5 GeV^2 is 0.122+/-0.003(stat.)+/-0.010(syst.).Comment: 7 pages, 3 figures, 1 table, RevTeX late