Code Predictions Research Articles

Shear behavior of shallow-wide beams strengthened by external SHCC jacket

ABSTRACT Shallow wide beams in structural systems are a good solution for many architectural constraints. In addition, these beams give construction time saving because of the simplicity of formwork and reinforced placement. Structural deficiency arises in the ultimate shear capacity of such beams as some codes neglect the contribution of shear reinforcement. Shear strengthening by Strain-Hardening Cementations Composites (SHCC) in form of a 2-sided or u-shaped jacket along shear spans provides a reliable solution.SHCC is an engineered cementitious composite having far superior to conventional cement mortar and has ingredients to contribute most optimally and efficiently to the various properties. The objective of this research is to study the shear behavior of shallow wide beams strengthened in shear with external SHCC layers along with the effect of vertical stirrups on the shear strength of shallow wide beams. An experimental program consisting of eleven specimens divided into three groups has been carried out. The investigation focused on studying the shear behavior of shallow wide beam with and without stirrups, examining the effect of thickness and grade of SHCC as a shear strengthening technique with various jacketing patterns with and without inserted external stirrups. The experimental results are further compared with predictions of particular international code provisions. Based on the comparative analysis of the conservative code's predictions for shallow beams, a modification is proposed to improve the predictions of the Egyptian code’s provisions for ultimate shear. The suggested equations account for the shear span to depth ratio, longitudinal reinforcement ratio, size effect, jacketing confinement, inclination of the compressive stresses to the beam axis besides the concrete/SHCC grades.

Sequential binary decay of light nuclear systems: An assessment of statistical model codes

The sequential decay of excited nuclei is described as a succession of binary processes involving fragments in their ground, excited-bound and unbound states. Primary together with secondary decays lead to the final mass and charge distributions. Asymmetric mass splittings involving nucleon emission up to symmetric binary ones are treated within the Weisskopf evaporation formalism, in a unified manner. This procedure was imple- mented in the Monte-Carlo multi-step statistical model code MECO (Multisequential Evaporation COde). We study the evolution of the calculated final mass and charge distributions from 40Ar* as a function of the excitation energy, up to complete dissociation. Our results are compared with the predictions of statistical evaporation codes based on different assumptions for the compound nucleus decay.

Performance of Shear Reinforcement against Punching Shear Loads

This research targets to maximize the ductility and strength of the reinforced concrete flat slabs. However, to be efficient, the shear reinforcement must be anchored well in the tension and compression zones of the slab. The test results on the slab-column connection models which provided with shear reinforcement are introduced in this study. The benefits of using shear reinforcement are to reduce the slab thickness, and to minimize both the cost and the total weight of the structure. Twelve flat slab specimens have been tested to study the effect of different types of steel RFT on the punching shear of the flat slab. The experimental parameters include no shear reinforcement which study the advantage of using tension RFT ONLY against punching shear, no shear reinforcement which study the advantage of using compression RFT against punching shear, shear RFT (Vertical Stirrups) which study the effect of using shear RFT with constant distribution 0.5d, and a new distribution of shear stirrups which study the effect of using new different width & spacing of vertical stirrups. The twelve specimens were loaded with concentrated load at the mid span until failure. The general behavior of the deformation of the tested slab specimens was examined and recorded (cracking, deflection, and strain in both steel and concrete). A comparison established between the experimental and the numericaltheoretical results obtained from applying the punching shear strength formula given in design codes, and finite element modeling analysis; ABAQUS 2017 software package was used for this analysis. A total of six building codes were examined with regard to their provisions concerning the punching shear. A comparison had been made between the research test results and the codes equations to improve the methods of the analysis about the flat slabs. This study aimed to improve the punching shear capacity of flat slab which leads to more accurate results compared with the codes predictions. To achieve this aim, an experimental and numerical study was carried out for this investigation.

Magnetic Field Penetration Into a Metal Enclosure Using an ELF/VLF Loop Antenna

The ability of extremely and very low frequency (ELF/VLF, 0–30 kHz) radio waves to penetrate conductive media is well established. Magnetic field penetration into a thin but highly conductive box using an ELF/VLF loop antenna transmitter is investigated. The work is relevant for electromagnetic shielding of ELF/VLF sensors, defect detection, inductive power transfer, and through container imaging. Analytical solutions are reviewed for related shielding problems, however, determining the penetration through a realistic shield geometry and finite sized near-field source requires a numerical approach. Surface integral equation (SIE) methods are well suited for shield modeling due to the low surface area to volume ratio of the shield. Method of moment techniques have been successfully applied to solving SIEs in the past, however, enforcing algorithm stability at low frequencies is known to require considerable effort. To alleviate the low-frequency concerns, a high-order locally corrected Nystrom (LCN) scheme is utilized to solve an SIE based on an augmented Muller formulation of Maxwell's equations. To validate the LCN simulations, an experiment is conducted using a loop antenna inside a 1.2 m aluminum cube of 2.7 mm thickness with an external ELF/VLF loop transmitter. Experimental results are shown to match within 3 dB of the LCN code predictions.

Four α-particle decay of the excited 16O* quasi-projectile in the 16O + 12C reaction at 130 MeV

The four α-particle decay of the excited 16O* quasi-projectile (QP) produced in peripheral 16O + 12C reactions at 130 MeV is studied in detail. The different decay channels leading to the four α-particle final state are reconstructed from an event-by-event analysis of α correlations through the population of intermediate 8Be and 12C resonant states. A small but non-negligible contribution of 8Begs evaporation is observed. The branching ratios of the different evaporation channels are compared to the prediction of an Hauser-Feshbach code (once characteristics of the QP source are extracted from the experimental data), which very accurately reproduces all the inclusive observables of the reaction. However, significative deviations are observed. In particular, the experimental population of the Hoyle state is significantly lower than the predictions of the statistical model, suggesting possible structure effects in the Coulomb barrier and/or in the transmission coefficients.

Profile Extrusion: Experimental Assessment of a Numerical Code to Model the Temperature Evolution in the Cooling/Calibration Stage

Designing an industrial calibration system that ensures fast and uniform cooling of a complex extruded profile is always a difficult task. Numerical tools are a valuable aid for the design of these systems in order to achieve fast, low‐cost, and effective solutions. This work comprises the experimental validation of a numerical code, previously developed to support the design of profile extrusion calibration systems, using data collected from an industrial extrusion line. The referred numerical code was developed in the open‐source computational library, OpenFOAM, being able to predict the heat exchanges between the polymer and the calibrator during the profile extrusion cooling stage. The good agreement obtained between the numerical code predictions and the experimental measurements allowed us to confirm the code accuracy. Subsequently, and in order to demonstrate the usefulness of the numerical code, a numerical study was carried out based on an optimization algorithm aimed at improving the performance of the studied calibration system. As a result, the study led to the proposal of an alternative setup, which presents a simpler constructive solution and a better performance than the existing one. POLYM. ENG. SCI., 59:2367–2376, 2019. © 2019 Society of Plastics Engineers

Behaviour and design of air-cured GFRP-reinforced geopolymer concrete square columns

Conventional steel-reinforced ordinary Portland cement concrete is prone to corrosion. Geopolymer concrete is a new durable cementitious material, and the glass fibre-reinforced polymer (GFRP) is an attractive alternative to steel because of GFRP's compelling physical and mechanical properties, corrosion resistance and electromagnetic transparency. This study investigates the structural properties of 11 air-cured square geopolymer concrete columns reinforced with GFRP bars at various stirrup spacings of 50, 100 and 150 mm. The specimens were tested under varying loading conditions to generate interaction diagrams for comparison with theoretical predictions from existing codes and standards. Effective confinement and higher ductility were achieved by reducing the stirrup spacing. High strains indicating buckling or rupture of the longitudinal GFRP bars and confinement of the core were measured. The comparison between the experimental data and design codes showed that the load-carrying capacity of the columns were favourably under-predicted from a design viewpoint when the compressive GFRP bars were excluded. The strength of the concentrically loaded columns was up to 39·6% higher than the code predictions. The GFRP-reinforced geopolymer concrete columns showed a 10·8% average increment in the load-carrying capacity over their plain concrete sections.

Measurement of deuteron-induced nuclear reactions cross-sections on 197Au and on natCu focused on the theranostic 197m,gHg

Theranostic 197m,gHg of high specific activity may be produced by proton or deuteron activation of gold. The particle choice affects the isomeric ratio. In order to compare both projectiles, we re-measured cross-sections of the nuclear reactions 197Au(d,x)197mHg, 197gHg, 198mAu, 198gAu, 196m2Au, 196m1+gAu in the energy range of 8.3–19.7 MeV having employed usual stacked-foil method. The obtained values were compared with previously measured data and with prediction of the TALYS nuclear reaction model code adopted from the TENDL-2017 library. Experimental data were used for calculation of the thick target yields. The yields for the isomeric pair 197m,gHg were confronted with those for recently re-measured proton-induced reactions. We also provide a new data set for the reaction natCu(d,x)63Zn.

Preliminary study on the impact of initial imperfections on the post‐buckling rotation of square hollow sections in uniform bending

ABSTRACTWith increasing use of high‐strength steel grades, the need for more accurate design specifications arises, with the aim of fully exploiting the material benefits and create economic advantages. According to Eurocode 3, the maximum rotational capacity is limited and linked to the definition of cross‐sectional classes. For class 1, the rotation θ is assumed to be “infinite”, while it drops significantly for class 2 and 3 to a maximum rotation of θpl and θel, respectively. In reality, in spite of their lower hardening capacity and ultimate strains, high‐strength steel sections display a non‐negligible rotational capacity that exceeds these code predictions, which were developed for mild steel and with a level of analysis in mind that is suitable for hand calculations. For an increased use of high‐strength steel sections, it is thus very important to understand and to be able to predict a more realistic deformation and rotation capacity, with the aim of implementing the findings in tools for advanced, FEM‐based Design by Analysis (DbA) approaches. As an initial step in this direction, the proposed paper shows the results from numerical calculations on the rotational capacity of HSS rectangular hollow sections. The numerical results are calibrated against laboratory tests. Consequently, different rectangular cross section dimensions but also variations of the steel grade and the thickness are chosen and calculated in the finite element program ABAQUS.

Simulator design for low pressure plasma discharges in planar geometry

A design of a simulator code to determine the plasma characteristics in planar geometry discharges is presented. The experimentally obtained parameters are compared to the code predictions. The experimental plasma discharge characteristics were carried out using 99.99% nitrogen as the working gas at typical pressure values in the range 0.1–0.6 Torr. The simulator code was used to obtain the discharge current-voltage, showing compatibility with experimental values. The minimum breakdown voltage at the minimum gas pressure was also obtained. The relation between the discharge current at different anode-cathode distances was also determined.

Measurement of cross-sections of proton-induced nuclear reactions on 197Au focused on the production of the theranostic pair 197m,gHg

We measured cross-sections of the nuclear reactions 197Au(p,x)197mHg, 197gHg, 195mHg, 195gHg, 196m2Au, 196m1+gAu, 194m+gAu in the energy range of 6.4–35.3 MeV having used stacked-foil technique with high purity gold foils. The results were compared with previously published data and with prediction of the TALYS nuclear reaction model code adopted from the TENDL-2017 library. Thick target yields were deduced from the measured data. Production of the theranostic isomeric pair 197m,gHg is thoroughly discussed.

Eccentric compression behavior of concrete-encased-and-filled steel tube columns with high-strength circular steel tube

An experimental research was conducted for the eccentric compression behavior of concrete-encased-and-filled steel tube (CEFT) columns with high-strength circular steel tube. Five eccentrically loaded columns and one concentrically loaded column were tested under monotonic axial compression. The parameters of the test specimens included axial-load eccentricity, tie spacing, and the use of concrete encasement. In addition to conventional perimeter ties, U-cross ties were used to prevent the premature spalling of thin concrete encasement as well as local buckling of longitudinal rebars. Although early vertical cracking occurred at the compressive face, the outer concrete significantly contributed to the stiffness and strength of the composite column without the premature failure. The test strengths were compared with the predictions of current design codes, addressing contributions of the whole encasement. The CEFT specimens showed substantial ductility even after the concrete crushing, owing to the increased resistance of the high-strength circular steel tube and confined infill concrete. To verify overall behavior of the test specimens, nonlinear numerical analysis using a fiber model was performed.

Adherence to the Street Code Predicts an Earlier Anticipated Death

Objectives: Criminologists have long been interested in the relationship between subcultural attitudes and antisocial behavior, with Anderson’s street code thesis being the most recent and often researched foray in this area. Relatedly, scholars have begun to investigate the risk factors associated with the anticipation of early death. Extant research, however, has yet to empirically test Anderson’s hypothesis that subscription to the street code is predictive of an anticipated early death. This study contributes to the literatures on the street code as well as fatalism by investigating the link between these two constructs. Methods: Using data from a sample of serious youthful offenders, we examine whether street code values are related to the anticipation of a short life span using a number of multivariate regression techniques controlling for a range of individual- and community-level variables. Results: Results show adherence to the street code is significantly associated with an anticipated early death among the sample of delinquent youth. Further, the relationship between street code and anticipated early death holds across race/ethnicity and gender, and results are not sensitive to the measurement of an anticipated early death. Findings from the current research are discussed, along with implications for policy and future research.

The CASUALIDAD Method for Uncertainty Evaluation of Best-Estimate System Thermal-Hydraulic Calculations

Predictive Modeling Methodology constitutes an innovative approach to perform uncertainty analysis (UA) that reduces the subjective and user-defined ways to manage experimental data and derive uncertainty of input parameters that characterize the Propagation of Input Uncertainties (PIU) and/or Propagation of Output Accuracies (POA) methods. The Code with the capability of Adjoint Sensitivity and Uncertainty AnaLysis by Internal Data ADjustment and assimilation (CASUALIDAD) method can be developed as a fully deterministic method based on advanced mathematical tools to internally perform in the thermal-hydraulic system code the sensitivity analysis (SA) and the UA. The method is based upon powerful mathematical tools to perform the SA and upon the Data Adjustment and Assimilation methodology by which experimental observations are combined with code predictions and their respective errors through the application of the Bayes theorem and of the Principle of Maximum Likelihood to provide an improved estimate of the system state and of the associated uncertainty considering all input parameters that affect any prediction. The methodology has been structured in two main steps. The first step generates the database of improved estimations (IEs) starting from the available set of experimental data and related qualified calculations. The second step deals with the use of the selected (from the obtained database) set of IEs for the uncertainty evaluation of the predicted nuclear power plant transient scenario. The proposed methodology clearly interrelates in a consistent and robust framework the code validation issue with the evaluation of the uncertainty of code responses passing through the quantification of input uncertainty parameters of code models, thus constituting a step forward with respect to the subjectivity of the current methods based on PIU and/or POA.

On the post‐buckling rotational capacity of square hollow sections in uniform bending

AbstractNominated for the Bernt Johansson Outstanding Paper Awards at Nordic Steel 2019The growing popularity of high‐strength steel grades leads to the need for more accurate design specifications, with the aim of fully exploiting the material benefits and creating economic advantages. According to Eurocode 3, the maximum rotational capacity of a section is limited and linked to the definition of cross‐sectional classes. For class 1, the rotational limit θ is assumed to be ”infinite“, whereas it drops significantly for classes 2 and 3 to a maximum rotation of φpl and φel, respectively. In reality, despite their lower hardening capacity and ultimate strains, high‐strength steel sections exhibit a non‐negligible rotational capacity that exceeds these code predictions, which were developed for mild steel and with a level of analysis in mind that is suitable for hand calculations. In order to achieve greater use of high‐strength steel sections, it is thus very important to understand and be able to predict a section's deformation and rotational capacity more accurately, with the aim of implementing the findings in tools for advanced, FEM‐based design by analysis (DbA) approaches. As an initial step in this direction, this paper shows the results from numerical calculations of the rotational capacity of HSS rectangular hollow sections. The numerical results were calibrated against laboratory tests. Consequently, different rectangular cross‐section dimensions and variations of the steel grade and thickness were chosen and analysed in the ABAQUS finite element software.

An unstructured CFD mini‐application for the performance prediction of a production CFD code

SummaryMaintaining the performance of large scientific codes is a difficult task. To aid in this task, a number of mini‐applications have been developed that are more tractable to analyze than large‐scale production codes while retaining the performance characteristics of them. These “mini‐apps” also enable faster hardware evaluation and, for sensitive commercial codes, allow evaluation of code and system changes outside of access approval processes. In this paper, we develop MG‐CFD, a mini‐application that represents a geometric multigrid, unstructured computational fluid dynamics (CFD) code, designed to exhibit similar performance characteristics without sharing commercially sensitive code. We detail our experiences of developing this application using guidelines detailed in existing research and contributing further to these. Our application is validated against the inviscid flux routine of HYDRA, a CFD code developed by Rolls‐Royce plc for turbomachinery design. This paper (1) documents the development of MG‐CFD, (2) introduces an associated performance model with which it is possible to assess the performance of HYDRA on new HPC architectures, and (3) demonstrates that it is possible to use MG‐CFD and the performance models to predict the performance of HYDRA with a mean error of 9.2% for strong‐scaling studies.

Experimental decay-heat simulation-benchmark for 14 MeV neutrons & complex inventory analysis with FISPACT-II

Nuclear inventory simulations have a vital role to play in the planning and execution of future fusion experiments and power plants. They are able to predict the transmutation (burn-up) response of material compositions under neutron irradiation, thus providing information about the build-up of impurities that could impact on material performance. The inventory evolution also quantifies the radiological response of a material by tracing the production (and decay) rates of radioactive nuclides. This information can be used to plan maintenance schedules at nuclear facilities, satisfy nuclear regulators during reactor planning, and quantify the waste disposal needs during reactor decommissioning.However, the validity of inventory simulations must be verified to give confidence in the predictions. This paper describes a validation and verification (V&V) benchmark exercise that tests the quality of nuclear code predictions. Such benchmarks are an important part of the development and release of the FISPACT-II inventory code and its associated input nuclear data libraries. This paper describes the latest V&V based on the fusion decay-heat measurements performed at the Japanese FNS facility. Rigorous and detailed assessment techniques, focussed on the complex breakdown of decay-heat contributions from individual radionuclides, have been employed to interpret the simulated results, benchmark the data against the experimental measurements, and to compare results from different international nuclear data libraries. Example results are presented and discussed for nickel, iron, niobium, tungsten, chromium, and osmium, using FISPACT-II simulations performed with TENDL-2017, JEFF-3.3, ENDF/B-VIII.0, EAF2010, and IRDFF-1.05 nuclear cross section libraries.

CUPID 코드 기반 수소거동 해석 모델 방법론 연구

In the wake of Fukushima accident, controlling the hydrogen risk has become a priority for the safety of nuclear power plants. While lumped-parameter system codes are computationally efficient, they do not provide precise information on the local hydrogen distribution. On the other hand, computational fluid dynamics (CFD) codes provide detailed information on local phenomena. In this work, a three-dimensional CFD simulation of the PANDA facility is developed using the CFD code, CUPID. Specifically, the simulation of the thermal-hydraulic experiments OECD/SETH-2 ST1 test series is presented in the current paper. The code predictions of the concentration during the mixing and stratification phases are compared to the experimental data. This effort is part of an ongoing effort to understand the local behavior of steam-hydrogen releases in nuclear reactor containment in support of accident management and simultaneously serves as a validation of the CUPID code to assess it applicability for containment analyses.

Laboratory and numerical tests on real crane runway girder with box section

This paper investigates the local stresses in crane runway girders with welded box section due to wheel loading. The effects of load eccentricity are studied in detail for webs with and without longitudinal stiffeners. Since current design codes only give stress formulae for I-sections, a new analytical model is presented in this paper. This extended analytical model for eccentric loads allows for consideration of the stiffness contribution of the upper flange and of the additional web supporting effect of longitudinal stiffeners, if present.Additionally, laboratory tests on a full scale crane runway girder with welded box section and corresponding finite element calculations are presented. The local stresses of both are compared with the new analytical model and with code predictions. Concentric wheel loading as well as eccentric loading is studied. Three different load positions are investigated: LP I with longitudinal web stiffeners, LP III without stiffeners and LP II directly at a diaphragm. Moreover, additional fatigue tests due to cyclic wheel loading are presented for all three load positions.

Predicting reinforcing bar development length using polynomial chaos expansions

The bond stress of a reinforcing bar in a cementitious matrix varies along the bar length and is difficult to quantify. Thus, design code provisions refer to the concept of bar development length and rely on statistical analysis of rebar-pull-out test results. In the present study, a novel data-driven predictive model based on Polynomial Chaos Expansions (PCE) was developed to predict the reinforcing bar development length using 534 experimental results of simple pull-out tests on short unit bar lengths. The predictive capability of PCE was compared to that of other data-driven models, namely the Response Surface Method (RSM) and Artificial Neural Networks (ANN). Moreover, predictions of the PCE, RSM and ANN were further compared with calculations of three commonly used design code formulas (i.e., ACI 318-14, ACI 408R-03, and Eurocode 2) and predictions of two existing empirical models (i.e. Model Code 2010 and Hwang et al. model). A parametric study was conducted to explore the sensitivity of the proposed model to influential input parameters. It was found that the Polynomial Chaos Expansions model offers a powerful predictive tool for reinforcing bar bond strength. The model was able to capture trends that differ from that of existing models that assume unrealistic uniform bond stress along the rebar. This flexible and data intensive model for predicting rebar bond stress and full embedment length could offer an intelligent platform for accommodating new bar materials, new test data, and calibrating existing design provisions to keep design codes relevant.