Bolted beam-column moment connections between cold-formed steel members

ABSTRACT Twelve beam-to-column connections between cold-formed steel sections consisting of three beam depths and four connection types were tested in isolation to investigate their behavior based on strength, stiffness and ductility. Resulting moment-rotation curves indicate that the tested connections are efficient moment connections where moment capacities ranged from about 65% to 100% of the connected beam capac-ity. With a moment capacity of greater than 80% of connected beam member capacity, some of the connec-tions can be regarded as full strength connections. Connections also possessed sufficient ductility with rota-tions of 20 mRad at failure although some connections were too ductile with rotations in excess of 30 mRad. Generally, most of the connections possess the strength and ductility to be considered as partial strength con-nections. The ultimate failures of almost all of the connections were due to local buckling of the compression web and flange elements of the beam closest to the connection.

Spectral–texture feature extraction using statistical moments with application to object-based vegetation species classification

The use of appropriate features to characterise an output class or object is critical for all classification problems. In order to find optimal feature descriptors for vegetation species classification in a power line corridor monitoring application, this article evaluates the capability of several spectral and texture features. A new idea of spectral–texture feature descriptor is proposed by incorporating spectral vegetation indices in statistical moment features. The proposed method is evaluated against several classic texture feature descriptors. Object-based classification method is used and a support vector machine is employed as the benchmark classifier. Individual tree crowns are first detected and segmented from aerial images and different feature vectors are extracted to represent each tree crown. The experimental results showed that the proposed spectral moment features outperform or can at least compare with the state-of-the-art texture descriptors in terms of classification accuracy. A comprehensive quantitative evaluation using receiver operating characteristic space analysis further demonstrates the strength of the proposed feature descriptors.

What information counts at the moment of practice? Information practices of renal nurses

Aims. This article is a report of a study done to identify how renal nurses experience information about renal care and the information practices that they used to support everyday practice. Background. What counts as nursing knowledge remains a contested area in the discipline yet little research has been undertaken. Information practice encompasses a range of activities such as seeking, evaluation and sharing of information. The ability to make informed judgement is dependent on nurses being able to identify relevant sources of information that inform their practice and those sources of information may enable the identification of what knowledge is important to nursing practice. Method. The study was philosophically framed from a practice perspective and informed by Habermas and Schatzki; it employed qualitative research techniques. Using purposive sampling six registered nurses working in two regional renal units were interviewed during 2009 and data was thematically analysed. Findings. The information practices of renal nurses involved mapping an information landscape in which they drew on information obtained from epistemic, social and corporeal sources. They also used coupling, a process of drawing together information from a range of sources, to enable them to practice. Conclusion. Exploring how nurses engage with information, and the role the information plays in situating and enacting epistemic, social and corporeal knowledge into everyday nursing practice is instructive because it indicates that nurses must engage with all three modalities in order to perform effectively, efficiently and holistically in the context of patient care. © 2011 The Authors. Journal of Advanced Nursing © 2011 Blackwell Publishing Ltd.

The iPhone Moment, the Apple Brand and the creative consumer : From “hackability and usability” to cultural generativity

In this chapter I position the iPhone as a “moment” in the history of cultural technologies. Drawing predominantly on advertising materials and public conversations about other "moments" in the history of personal computing and focusing on Apple’s role in this history, I argue that the design philosophy, marketing, and business models behind the iPhone (and now the iPad) have decisively reframed the values of usability that underpin software and interface design in the consumer technology industry, marking a distinctive shift in the history and contested futures of digital culture.

Section moment capacity tests of LiteSteel Beams

The LiteSteel Beam (LSB) is a new cold-formed hollow flange channel section developed by OneSteel Australian Tube Mills using their patented dual electric resistance welding and automated continuous roll-forming process. It has a unique geometry consisting of torsionally rigid rectangular hollow flanges and a relatively slender web. In addition to this unique geometry, the LSB sections also have unique characteristics relating to their stress-strain curves, residual stresses, initial geometric imperfections and hollow flanges that are not encountered in conventional hot-rolled and cold-formed steel channel sections. An experimental study including 20 section moment capacity tests was therefore conducted to investigate the behaviour and strength of LSB flexural members. The presence of inelastic reserve bending capacity in these beams was investigated in detail although the current design rules generally limit the section moment capacities of cold-formed steel members to their first yield moments. The ultimate moment capacities from the tests were compared with the section moment capacities predicted by the current cold-formed and hot-rolled steel design standards. It was found that compact and non-compact LSB sections have greater moment capacities than their first yield moments. The current cold-formed steel design standards were found to be conservative in predicting the section moment capacities of compact and non-compact LSB sections while the hot-rolled steel design standards were able to better predict them. This paper has shown that suitable modifications are needed to the current design rules to allow the inclusion of available inelastic bending capacities of LSBs in design.

Plastic bending behaviour and section moment capacities of mono-symmetric LiteSteel Beams with web openings

Recently developed cold-formed LiteSteel beam (LSB) sections have found increasing popularity in residential, industrial and commercial buildings due to their light weight and cost-effectiveness. Currently, there is significant interest in the use of LSB sections as flexural members in floor joist systems, although they can be used as flexural and compression members in a range of building systems. The plastic bending behaviour and section moment capacity of LSB sections with web holes can be assumed to differ from those without, but have yet to be investigated. Hence, no appropriate design rules for determining the section moment capacity of LSB sections with web holes are yet available. This paper presents the results of an investigation of the plastic bending behaviour and section moment capacity of LSB sections with circular web holes. LSB sections with varying circular hole diameters and degrees of spacing were considered. The paper also describes the simplified finite element (FE) modelling technique employed in this study, which incorporates all of the significant behavioural effects that influence the plastic bending behaviour and section moment capacity of these sections. The numerical and experimental test results and associated findings are also presented.

Numerical method for predicting the elastic lateral distortional buckling moment of a mono-symmetric beam with web openings

When used as floor joists, the new mono-symmetric LiteSteel beam (LSB) sections require web openings to provide access for inspections and various services. The LSBs consist of two rectangular hollow flanges connected by a slender web, and are subjected to lateral distortional buckling effects in the intermediate span range. Their member capacity design formulae developed to date are based on their elastic lateral buckling moments, and only limited research has been undertaken to predict the elastic lateral buckling moments of LSBs with web openings. This paper addresses this research gap by reporting the development of web opening modelling techniques based on an equivalent reduced web thickness concept and a numerical method for predicting the elastic buckling moments of LSBs with circular web openings. The proposed numerical method was based on a formulation of the total potential energy of LSBs with circular web openings. The accuracy of the proposed method’s use with the aforementioned modelling techniques was verified through comparison of its results with those of finite strip and finite element analyses of various LSBs.

Member moment capacities of mono-symmetric LiteSteel beam floor joists with web openings

Recently developed cold-formed LiteSteel beam (LSB) sections have found increasing popularity in residential, industrial and commercial buildings due to their light weight and cost-effectiveness. Another beneficial characteristic is that they allow torsionally rigid rectangular flanges to be combined with economical fabrication processes. Currently, there is significant interest in the use of LSB sections as flexural members in floor joist systems. When used as floor joists, these sections require openings in the web to provide access for inspection and other services. At present, however, there is no design method available that provides accurate predictions of the moment capacities of LSBs with web openings. This paper presents the results of an investigation of the buckling and ultimate strength behaviour of LSB flexural members with web openings. A detailed fine element analysis (FEA)-based parametric study was conducted with the aim of developing appropriate design rules and making recommendations for the safe design of LSB floor joists. The results include the required moment capacity curves for LSB sections with a range of web opening combinations and spans and the development of appropriate design rules for the prediction of the ultimate moment capacities of LSBs with web openings.

The Convergent Media Policy Moment

This paper will consider some of the wider contextual and policy questions arising out of four major public inquiries that took place in Australia over 2011–2012: the Convergence Review, the National Classification Scheme Review, the Independent Media Inquiry (Finkelstein Review) and the National Cultural Policy. This paper considers whether we are now witnessing a ‘convergent media policy moment’ akin to the ‘cultural policy moment’ theorized by Australian cultural researchers in the early 1990s, and the limitations of various approaches to understanding policy – including critiques of neoliberalism – in understanding such shifts. It notes the rise of ‘soft law’ as a means of addressing the challenges of regulatory design in an era of rapid media change, with consideration of two cases: the approach to media influence taken in the Convergence Review, and the concept of ‘deeming’ developed in the National Classification Scheme Review.

Improving the moment capacities of hollow flange cold-formed Litesteel Beams using web stiffeners

The LiteSteel Beam (LSB) is a new hollow flange section developed in Australia with a unique geometry consisting of torsionally rigid rectangular hollow flanges and a relatively slender web. The LSB is subjected to a relatively new Lateral Distortional Buckling (LDB) mode when used as flexural members. Unlike the commonly observed lateral torsional buckling, lateral distortional buckling of LSBs is characterised by cross sectional change due to web distortion. Lateral distortional buckling causes significant moment capacity reduction for LSBs with intermediate spans. Therefore a detailed investigation was undertaken to determine the methods of reducing the effects of lateral distortional buckling in LSB flexural members. For this purpose the use of web stiffeners was investigated using finite element analyses of LSBs with different web stiffener spacing and sizes. It was found that the use of 5 mm steel plate stiffeners welded or screwed to the inner faces of the top and bottom flanges at third span points considerably reduced the lateral distortional buckling effects in LSBs. Suitable design rules were then developed to calculate the enhanced elastic lateral distortional buckling moments and the higher ultimate moment capacities of LSBs with the chosen web stiffener arrangement. This paper presents the details of this investigation and the results.

Distinguishing between mean-field, moment dynamics and stochastic descriptions of birth-death-movement processes

Mathematical descriptions of birth–death–movement processes are often calibrated to measurements from cell biology experiments to quantify tissue growth rates. Here we describe and analyze a discrete model of a birth–death-movement process applied to a typical two–dimensional cell biology experiment. We present three different descriptions of the system: (i) a standard mean–field description which neglects correlation effects and clustering; (ii) a moment dynamics description which approximately incorporates correlation and clustering effects, and; (iii) averaged data from repeated discrete simulations which directly incorporates correlation and clustering effects. Comparing these three descriptions indicates that the mean–field and moment dynamics approaches are valid only for certain parameter regimes, and that both these descriptions fail to make accurate predictions of the system for sufficiently fast birth and death rates where the effects of spatial correlations and clustering are sufficiently strong. Without any method to distinguish between the parameter regimes where these three descriptions are valid, it is possible that either the mean–field or moment dynamics model could be calibrated to experimental data under inappropriate conditions, leading to errors in parameter estimation. In this work we demonstrate that a simple measurement of agent clustering and correlation, based on coordination number data, provides an indirect measure of agent correlation and clustering effects, and can therefore be used to make a distinction between the validity of the different descriptions of the birth–death–movement process.

Wellbeing as a process of accrual : beyond subjectivity and beyond the moment

Although the notion of wellbeing is popular in contemporary literature, it is variously interpreted and has no common definition. Such inconsistencies in definition have particular relevance when considering wellbeing programs designed for children. By developing a broader conceptualisation of wellbeing and its key elements, the range of programs and services developed in the name of wellbeing will achieve a more consistent cross-disciplinary focus to ensure that the needs of the individual, including children, can more accurately be addressed. This paper presents a new perspective on conceptualising wellbeing. The authors argue that conceptualising wellbeing as an accrued process has particular relevance for both adults and children. A definition for accrued wellbeing is presented in an attempt to address some of the current deficiencies in existing understandings of an already complicated construct. The potential for the ideas presented when considering wellbeing as a process of accrual may have further application when considered beyond childhood.

Determination of the magnetic moment by QCD sum rules

The magnetic moment of the Λ hyperon is calculated using the QCD sum-rule approach of Ioffe and Smilga. It is shown that μΛ has the structure μΛ=(2/3(eu+ed+4es)(eħ/2MΛc)(1+δΛ), where δΛ is small. In deriving the sum rules special attention is paid to the strange-quark mass-dependent terms and to several additional terms not considered in earlier works. These terms are now appropriately incorporated. The sum rule is analyzed using the ratio method. Using the external-field-induced susceptibilities determined earlier, we find that the calculated value of μΛ is in agreement with experiment.

Application of Maclaurin Series in Structural Analysis

In the simple theory of flexure of beams, the slope, bending moment, shearing force, load and other quantities are functions of a derivative of y with respect to x. It is shown that the elastic curve of a transversely loaded beam can be represented by the Maclaurin series. Substitution of the values of the derivatives gives a direct solution of beam problems. In this paper the method is applied to derive the Theorem or three moments and slope deflection equations. The method is extended to the solution of a rigid portal frame. Finally the method is applied to deduce results on which the moment distribution method of analyzing rigid frames is based.

Special Issue on Spatial Moment Techniques for Modelling Biological Processes

Over the last two decades, there has been an increasing awareness of, and interest in, the use of spatial moment techniques to provide insight into a range of biological and ecological processes. Models that incorporate spatial moments can be viewed as extensions of mean-field models. These mean-field models often consist of systems of classical ordinary differential equations and partial differential equations, whose derivation, at some point, hinges on the simplifying assumption that individuals in the underlying stochastic process encounter each other at a rate that is proportional to the average abundance of individuals. This assumption has several implications, the most striking of which is that mean-field models essentially neglect any impact of the spatial structure of individuals in the system. Moment dynamics models extend traditional mean-field descriptions by accounting for the dynamics of pairs, triples and higher n-tuples of individuals. This means that moment dynamics models can, to some extent, account for how the spatial structure affects the dynamics of the system in question.