662 research outputs found
Deformation and strain limits for IPB-loaded high strength steel CHS joints
No full textIn this study, existing deformation limits are first re-examined to investigate if they can be rationally extended to high strength steel circular hollow section (CHS) joints that are subjected to in-plane bending (IPB) moment. It is pointed out that existing deformation limits, which have been developed and validated primarily for mild steel joints, need to be modified when high strength steels are involved. By noting that the ductility of IPB-loaded joints can be significantly reduced with the use of high strength steel, a new deformation limit is proposed which allows less deformation to less ductile high strength steel joints. The deformation limit, proposed in terms of joint rotation angle, is validated both numerically and experimentally. In addition, a recently proposed strain limit criterion is also discussed. To provide a guide for obtaining converged strain from finite element (FE) analysis, mesh sensitivity study is comprehensively conducted. It is shown that the element size required for the convergence of strain is substantially smaller than that required for obtaining satisfactory global response such as joint load-deformation relationship. By applying a systematic FE modeling strategy, numerical investigation is made to check the feasibility of the 5% strain limit criterion which has recently been advocated by the revised draft of ISO 14346. While the limiting principal strain of 5% is shown to be reasonable for CHS-to-CHS joints loaded by IPB, for longitudinal branch plate-to-CHS joints, a lower limiting strain appears more appropriate.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Steel & Composite Structure
Simplified design equations for Plate-to-CHS T and X joints for use in codes
No full textThis paper deals with revised, simplified, consistent equations for plate-to-Circular Hollow Section (CHS) joints for inclusion in codes. After a short review of the background to these resistance equations in the current consolidated version of EN 1993-1-8 and those in ISO 14346, the background to these simplified new equations is discussed. The equations for Plate-to-Circular Hollow Section T and X joints (called TP and XP joints respectively) in the current EN 1993-1-8 are based on experimental data available up to 1991. They are further related to the equations for CHS T and X joints. Most of the data used are based on the ultimate joint resistance. A similar approach is used for the TP and XP equations in ISO 14346, but these are related to the updated equations for CHS T and X joints. Since the drafting of ISO 14346, new consistent numerical data from Voth became available where the resistance is not only based on the ultimate resistance but also takes the 3 %d0 joint deformation limit into account. The new equations in prEN 1993-1-8 are based on the Voth data, the de Winkel data and the Voth-Packer equations, but use a simplified uniform presentation which permits to relate joints with an I, H and RHS brace-to-CHS chord to these basic equations. Furthermore, the presented equations are based on the case of axial compression load in the plate, which is the lower bound of the compression and tension load casesSteel & Composite Structure
LIF AND MICROWAVE SPECTROSCOPY OF CHCHS
No full textAuthor Institution: Department of Chemical System Engineering, The University of Tokyo, Tokyo, 113-8656, Japan; Department of Basic Science, The University of Tokyo, Tokyo, 153-8902, JapanPrecise molecular constants of the CHCHS (vinylthio) radical in the ground vibronic level were determined by Fourier-transform microwave (FTMW) and FTMW-millimeter wave double-resonance spectroscopy}, \textit{J. Chem. Phys.} \underline{\textbf{123}}, 054324 (2005).}. The \textit{\ {B}} -- \textit{\ {X}} electronic transition of CHCHS was observed by LIF spectroscopy. Rotational constants in the upper electronic state were determined from a rotationally resolved LIF excitation spectrum of jet-cooled CHCHS. A dispersed fluorescence spectrum from the zero-vibtational level of the \textit{\ {B}} state was also measured to determine vibrational frequencies in the ground electronic state. The experimental molecular constants were compared with results of \textit{ab initio} calculations
Metajournals. A federalist proposal for scholarly communication and data aggregation
No full textWhile the EU is building an open access infrastructure of archives (e.g. OpenAIRE) and it is trying to implement it in the Horizon 2020 program, the gap between the tools and the human beings – researchers, citizen scientists, students, ordinary people – is still wide. The necessity to dictate open access publishing as a mandate for the EU funded research – ten years after the BOAI - is an obvious symptom of it: there is a chasm between the net and the public use of reason. To escalate the advancement and the reuse of research, we should federate the multitude of already existing open access journals in federal open overlay journals that receive their contents from the member journals and boost it with their aggregation power and their semantic web tools. The article contains both the theoretical basis and the guidelines for a project whose goals are: 1. making open access journals visible, highly cited and powerful, by federating them into wide disciplinary overlay journals; 2. avoiding the traps of the “authors pay” open access business model, by exploiting one of the virtue of federalism: the federate journals can remain little and affordable, if they gain visibility from the power of the federal overlay journal aggregating them; 3. enriching the overlay journals both through semantic annotation tools and by means of open platforms dedicated to host ex post peer review and experts comments; 4. making the selection and evaluation processes and their resulting data as much as possible public and open, to avoid the pitfalls (e. g, the serials price crisis) experienced by the closed access publishing model. It is about time to free academic publishing from its expensive walled gardens and to put to test the tools that can help us to transform it in one open forest, with one hundred flowers – and one hundred trailblazers
Effects of weld size on stress concentration factors of CHS-CFSHS joints
No full textThis paper aims to disclose the effects of weld size on hot spot stress in the calculation of fatigue performance of the joints. For this purpose, the author explored the hot spot stress of CHS-CFSHS T-joints, which consists of circular hollow section (CHS) braces and concrete-filled square hollow section (CFSHS) chords. After reviewing the previous studies and the relevant specifications on weld size, the author probes into the effects of weld size on the stress concentration factor (SCF) of CHS-CFSHS joints via finite-element analysis. The analysis show that the weld size directly affected the hot spot stress in both conditions, and the influence laws were largely the same; with the increase of weld size, the brace-side SCF plunged when the chord-size weld size remained the same, but the chord-side SCF changed slightly when the brace-side weld size was constant; the brace-side and chord-side SCF declined when the brace-side and chord-side weld sizes increased by the same amount. This research successfully determined the weld sizes that are consistent with the relevant specifications, and safe and simple to apply in actual engineering
Effects of weld size on stress concentration factors of CHS-CFSHS joints
No full textThis paper aims to disclose the effects of weld size on hot spot stress in the calculation of fatigue performance of the joints. For this purpose, the author explored the hot spot stress of CHS-CFSHS T-joints, which consists of circular hollow section (CHS) braces and concrete-filled square hollow section (CFSHS) chords. After reviewing the previous studies and the relevant specifications on weld size, the author probes into the effects of weld size on the stress concentration factor (SCF) of CHS-CFSHS joints via finite-element analysis. The analysis show that the weld size directly affected the hot spot stress in both conditions, and the influence laws were largely the same; with the increase of weld size, the brace-side SCF plunged when the chord-size weld size remained the same, but the chord-side SCF changed slightly when the brace-side weld size was constant; the brace-side and chord-side SCF declined when the brace-side and chord-side weld sizes increased by the same amount. This research successfully determined the weld sizes that are consistent with the relevant specifications, and safe and simple to apply in actual engineering
Metajournals. A federalist proposal for scholarly communication and data aggregation
No full textWhile the EU is building an open access infrastructure of archives (e.g. Openaire) and it is trying to implement it in the Horizon 2020 program, the gap between the tools and the human beings – researchers, citizen scientists,
students, ordinary people – is still wide. The necessity to dictate open access publishing as a mandate for the EU funded research – ten years after the BOAI - is an obvious symptom of it: there is a chasm between the net and the
public use of reason. To escalate the advancement and the reuse of research, we should federate the multitude of already existing open access journals in federal open overlay journals that receive their contents from the member journals and boost it with their aggregation power and their semantic web tools.
The article contains both the theoretical basis and the guidelines for a project whose goals are:
1. making open access journals visible, highly cited and powerful, by federating them into wide disciplinary overlay journals;
2. avoiding the traps of the “authors pay” open access business model, by exploiting one of the virtue of federalism: the federate journals can remain little and affordable, if they gain visibility from the power of the federal overlay journal aggregating them;
3. enriching the overlay journals both through semantic annotation tools and by means of open platforms dedicated to host ex post peer review and experts comments;
4. making the selection and evaluation processes and their resulting data as much as possible public and open, to avoid the pitfalls (e. g, the serials price crisis) experienced by the closed access publishing model.
It is about time to free academic publishing from its expensive walled gardens and to put to test the tools that can help us to transform it in one open forest, with one hundred flowers – and one hundred trailblazers
On Modelling Of FRP Wrapped Steel CHS Joints
No full textThe design of steel structures consisting mostly of Circular Hollow Sections (CHS) such as jacket structures and bridges is governed by fatigue loading due to the low fatigue resistance of the welded regions. A solution has been proposed where welding is completely avoided, thus eliminating the weakest factor of these structures. In this solution, joints are wrapped in FRP, which is bonded to the steel. Simple Finite Element (FE) models of these joints already exist. In this thesis, these models will be further developed in Abaqus for more accurate prediction of the behaviour of such FRP wrapped joints. A set of model and solver parameters will be established as a starting point formore detailed modelling of FRP wrapped joints with different geometry and static load conditions.Because of large complexity of the models, and inclusion of many contact interactions, Abaqus/Explicit should be used to model such joints. The anisotropic nature of the FRP requires elements that are robust and able to handle this anisotropy. Also the complex, curved and layered geometry of the wrap requires elements that discretize a 3D volume. Without the use of user subroutines, continuum shell elements are the only elements that meet this requirement.Prediction of the behaviour of axial joints was very accurate, although no unique set of input parameters for the Cohesive ZoneModel were found. This is because multiple failure modes occur at the same time, which makes the system very sensitive to some parameters and completely insensitive to other parameters. Prediction of more complex X-joints was not very accurate. This is mostly due to differences between the geometry of the model and the real life joint. The models did suffer from hourglass modes. Different methods of hourglass control had limited effect. It was found that as irregularity of the mesh increases, the effects of hourglass modes decreases. However, the effect of hourglass modes needs to be decreased further. A solution to do this is proposed at the end of this thesis.Civil Engineerin
Promoting and disseminating consistent and effective nutrition messages: Challenges and opportunities
No full textNutrition messages are a central part of policy making as well as communication via product information, advertising, healthcare advice and lifestyle campaigns. However, with amplified information (and misinformation) from a growing number of sources, inconsistent and conflicting food landscapes, and limited engagement from the public, nutrition messaging tensions have become more accentuated than previously. In this review, we focus on the challenges facing those wishing to effect dietary change through communication; and identify opportunities and future research questions. Beginning with a new working definition and taxonomy for the term ‘nutrition message’, we consider the evolution of public health nutrition messages from the past century and discuss which types of messages may be more effective. We then turn to the challenges of implementation and highlight specific barriers to recipients' understanding and change. While the evidence has many gaps and there is a need for systematic evaluation of nutrition messages, research indicates that recipients are more likely to act on fewer messages that provide clear benefits and which resonate with their perceived health needs, and which are relatively straightforward to implement. Effectiveness may be improved through consideration of how nutrition messages can be designed to complement key non-health drivers of food choice (taste, cost) and societal/cultural norms. Consistency can be achieved by aligning the wider food and messaging environment to desired public health actions; that is by ensuring that retail settings provide and signpost healthier choices, and that mass media nutrition messages work with, not against, public health advice
Structural Behaviour and Fire Design of Duplex and Ferritic Stainless Steel CHS Stub Columns
No full textCopyright © The Author(s) 2021. This paper investigates the structural behaviour and design of duplex and ferritic stainless steel stub columns with a circular hollow cross-section (CHS) at elevated temperature. A numerical model is developed to supplement the limited test results on stainless steel CHS stub columns in the literature. Following validation, the numerical approach is employed to gain an understanding of the critical behavioural characteristics which have not previously been studied. In addition, the paper considers and extends the continuous strength method (CSM) to include duplex and ferritic stainless steel for CHS stub columns in fire. The CSM employs a base curve linking the cross-section resistance to its deformation capacity and implements an elastic, linear hardening material model. The cross-sectional resistances obtained from the proposed CSM are compared with those from the numerical analysis, as well as with the standardised procedures in the European, American and Australia/New Zealand design standards. It is demonstrated that CSM can lead to more accurate and less scattered strength predictions than current design codes
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