bluuebunny/crossref_metadata_2025 huggingface dataset:
The supervisory alliance: Comparison of measures and implications for a supervision toolkit
Authors: Schweitzer Robert D. , Witham Merryn
Published: September 2017

Background Clinical supervision lies at the core of the professional development of clinicians providing services within a range of service settings. The supervisory alliance is regarded as the most important construct in effective supervision which underlies the importance of metrics to assess this construct. Aims materials and Method A cross‐sectional self‐report questionnaire design was used to examine clinical supervision constructs. The study used two scales measuring the supervisory alliance (SRQ and SWAI‐T), a scale measuring supervision satisfaction (SSQ) and a scale measuring disclosure (TDS). The questionnaires were administered to 127 clinical psychology trainees who were undertaking a practicum placement. Results Both scales measuring the alliance were positively correlated with satisfaction with supervision and disclosure, with similar sizes of correlation for each alliance scale. There was also a large, positive correlation between the two scales of measuring the alliance. Discussion Both scales were designed for use in supervision and are related to supervision outcome measures in the expected directions. Conclusion The SRQ has some distinct advantages over the SWAI‐T that lend the SRQ to be potentially more useful in clinical and research settings.
Academic Disputes about Adult‐Child Sexual Contact: A Critical Realist Appraisal
Authors: Pilgrim David
Published: September 2017

This paper examines the difference between the orthodox assumption that adult‐child sexual contact is both wrong and harmful and another that focuses upon moral panics. The latter view emphasises that the personal or social harm arising from adult‐child sexual contact is open to question. The tension between these two positions is laid out in order to examine their different assumptions about what exists (ontology), how it is understood (epistemology) and how we appraise power discrepancies in relationships (ethics). Resources from the philosophy of critical realism are deployed to critique the applicability of moral panic theory to child sexual abuse and understand the persistent presence of that theory, despite its poor evidence base. It is concluded that child sexual abuse is not a moral panic at all and that practitioners should be wary of the influence of this line of reasoning in their professional training and literature.

‘Examines the difference between the orthodox assumption that adult‐child sexual contact is both wrong and harmful and another that focuses upon moral panics’

Key Practitioner Messages

A minority academic position is that adult‐child sexual contact is usually harmless and ethically and psychologically warranted in society. Public and professional concern about the contact is depicted as a ‘moral panic’.

The recent history of that minority position is examined and justifications from policy libertarians and pro‐paedophile groups summarised.

Using resources from the philosophy of critical realism, this position is critiqued for its unwarranted reliance on the assumption that adult‐child sexual contact has become a moral panic.
Synthesis and Biological Evaluation of New Natural Phenolic (2E,4E,6E)‐Octa‐2,4,6‐trienoic Esters
Authors: Gandolfi Raffaella , Contini Alessandro , Pinto Daniela , Marzani Barbara , Pandini Stefano , Nava Donatella , Pini Elena
Published: September 2017

In the present study the esterification of the OH groups of resveratrol, caffeic acid, ferulic acid, and β‐sitosterol with an antioxidant polyconjugated fatty acid, (2E,4E,6E)‐octa‐2,4,6‐trienoic acid, was achieved. As the selective esterification of OH groups of natural compounds can affect their biological activity, a selective esterification of resveratrol and caffeic acid was performed by an enzymatic approach. The new resulting compounds were characterized spectroscopically (FT‐IR, NMR mono, and bidimensional techniques); when necessary the experimental data were integrated by quantum chemical calculations. The antioxidant, anti‐inflammatory and proliferative activity was evaluated. The good results encourage the use of these molecules as antioxidant and/or anti‐inflammatory agents in dermocosmetic application.
Pneumatosis cystoides intestinalis: lung window setting on CT
Authors: Kunishi Yosuke , Ota Mitsuyasu , Kato Yoshio , Maeda Shin
Published: September 2017

Key Clinical Message

Pneumatosis cystoides intestinalis is a rare and often presents nonspecific symptoms. In this case, CT imaging revealed air collection within the wall of the ileum, which was more clearly defined using the lung window setting. When we consider pneumatosis cystoides intestinalis, we should evaluate CT using the lung window setting.
Highly Efficient Oxidation of Amines to Aldehydes with Flow‐based Biocatalysis
Authors: Contente Martina L. , Dall'Oglio Federica , Tamborini Lucia , Molinari Francesco , Paradisi Francesca
Published: September 2017

A new mild and efficient process for the aqueous preparation of aldehydes, which are employed as flavour and fragrance components in food, beverage, cosmetics, as well as in pharmaceuticals, was developed using a continuous‐flow approach based on an immobilised pure transaminase‐packed bed reactor. HEWT, an ω‐transaminase from the haloadapted bacterium Halomonas elongata, has been selected for its excellent stability and substrate scope. Sixteen different amines were rapidly (3–15 min) oxidised to the corresponding aldehydes (90 to 99 %) with only 1 to 5 equivalents of sodium pyruvate. The process was fully automated, allowing for the in‐line recovery of the pure aldehydes (chemical purity >99 % and isolated yields above 80 %), without any further work‐up procedure.
An Effective Catalytic Hydroboration of Alkynes in Supercritical CO2 under Repetitive Batch Mode
Authors: Szyling Jakub , Franczyk Adrian , Stefanowska Kinga , Klarek Mateusz , Maciejewski Hieronim , Walkowiak Jędrzej
Published: September 2017

A facile method for the synthesis of unsaturated organoboron compounds by hydroboration of terminal and internal alkynes in supercritical (sc) CO2 has been presented for the first time. The reactions performed in scCO2 in the presence of Ru catalysts (selectivity, productivity) are compared with those in a traditionally used solvent or without it. Moreover, the catalytic systems based on the application of scCO2 have been successfully tested for the processes under repetitive batch conditions. This strategy permitted us to obtain boryl‐substituted olefins with high yields and selectivities up to the 16th catalytic cycle if using Ru(CO)Cl(H)(PPh3)3 as a catalyst. The process applied the self‐dosing catalyst, which is gradually released to the reaction mixture under supercritical conditions in the individual batch. Such an approach has a positive impact on process sustainability and economy.
Intermediates in the Oxidative Degradation of a Ruthenium‐Bound 2,2′‐Bipyridyl–Phenoxy Ligand during Catalytic Water Oxidation
Authors: Liu Yingying , Chen Gui , Yiu Shek‐Man , Wong Chun‐Yuen , Lau Tai‐Chu
Published: September 2017

Water‐oxidation catalysts (WOCs) based on transition‐metal complexes often undergo oxidative degradation of the ligands, which leads to unidentifiable products. We report herein the use of a ruthenium(III) complex bearing a 2,2′‐bipyridyl (bpy)–bis(phenoxy) ligand, [Ru(L)(pic)2]+ [1, H2L=6,6′‐bis(2‐hydroxyphenyl)‐2,2′‐bipyridine, pic=4‐picoline] as a WOC. The phenoxy‐type ligand in 1 is readily oxidized by CeIV in aqueous acidic medium to give a ruthenium bpy–dicarboxylate complex ([Ru(bda)(pic)2]+, H2bda=2,2′‐bipyridine‐6,6′‐dicarboxylic acid) via ruthenium bpy–phenoxybenzoquinone (1′) and ruthenium bpy–bis(benzoquinone) (1′′) intermediates. All four ruthenium species can oxidize water; however, 1 and 1′ are rapidly oxidized to 1′′ by CeIV. On the other hand, 1′′ is robust enough that it is responsible for the initial phase of O2 evolution before it is finally oxidized to CO2 and [Ru(bda)(pic)2]+, which is a highly active WOC.
03.18: Anchor bolt tensile load distribution: Effects of the column base‐plate design: Wide flange column bases – loading on additional line of bolts
Authors: de Macedo Rafael Scudelari , de Macedo Luiz Francisco Scudelari
Published: September 2017

The designer of column base elements usually considers that the uplift force existing in the column member is equally distributed on its anchor bolts. While this simplified approach may be used for the most common cases of a steel structures (for instance, when only 4 equally spaced anchor bolts exist in the column base design), it may lead the designer to overlook that the distribution of uplift loads is highly influenced by factors such as the rigidity of the base plate, the positioning of its stiffeners and the number and geometric arrangement of the anchor bolts. This unequal distribution of uplift loads on the anchor bolts may cause overloading on some of the anchor bolts, leading to diverting failure. This paper analyses through finite element several different wide‐flange column base elements, with varying plate thicknesses and geometry. The conclusion summarizes that the distribution of the loads on the anchor bolts largely depend on the typology of the base plate and suggests a revision of the codes to be more precise on when unequal axial tensile loads may arise on the anchor bolts and recommend more refined methods for the estimation of those unequally distributed loads.
03.21: Structural glued connections with different metal substrates
Authors: Machalická Klára , Eliášová Martina , Vokáč Miroslav
Published: September 2017

Intensive studies of polymer adhesives for structural applications have opened up new possibilities of glued usage connections in civil engineering, especially in façade applications. Facades have to fulfil not only architectural requirements but there are also construction and material technology requirements, as well as functionality. Façade cladding connections with other façade parts can be advantageously designed as glued joints. In dependence on particular application, adhesive bonding provides higher efficiency of workmanship in comparison with bolted connection and esthetical qualities, e.g. smooth, flat surface of façade cladding without visual interruption of bolts. Important benefit of glued connections in facades is elimination of local thermal bridge in comparison with bolted connections and possibility of stress peak reduction in dependence on adhesive and substrate stiffness and geometrical arrangement of the joint. Despite of wide usage of low strength and elastic silicone sealants for a long period of time in façades, there is a lack of information about semi‐flexible and semi‐rigid adhesives with higher strength and reasonable elongation at break. Building facade is a very specific type of usage for glued connections due to the requirements on durability, strict geometrical imperfections and joining of unconventional materials often used in the façade design. This paper reports on an experimental analysis focused on determining of the mechanical characteristics of two types of adhesive applied in double lap connection loaded by shear. The study comprises two basic substrate materials, aluminium and galvanised steel, with various surface treatments. Galvanized steel was used with clean, smooth surface and roughened surface; aluminium substrates were applied with clean smooth surface, roughened surface and with anodised covering to find out effect of roughening and anodization of aluminium on adhesion. Material and surface treatment has great influence not only on adhesion and thus strength of the joint, but also on failure mode, behaviour and safety of particular joint. Moreover, every necessary surface treatment creates higher labour intensity, higher time consumption and thus increased costs on building/facade construction.
03.22: Calculation model for moment ‐rotation relationship of bottom‐through‐diaphragm top‐ring connection between SST columns and HSS beams
Authors: Cao Shi , Shu Ganping , Lin Kunhong , Qin Ying , Fan Shenggang
Published: September 2017

Square steel tubular(SST) column and H‐shaped steel(HSS) beam systems have been widely used in engineering applications. The structural performance of this system largely depends on the behavior of the connections. This paper presents a new type of connections with bottom‐through‐diaphragm and top‐ring. Five specimens were tested under cyclic loadings to evaluate the seismic behavior and the moment‐rotation relationships. Finite element models were developed and compared with experimental testing to verify the accuracy of the model. The calculation equation of moment‐rotation curves were proposed according to the analytical data of finite element model. Furthermore, the moment‐rotation calculation model characterizing the general behavior of this new type connection were developed based on these parameters. The accuracy of the calculation model was examined by comparing with the results of finite element model. Finally, a reasonable moment‐rotation relationship was obtained using the parameters within this model.
03.34: European stiffened angle connections: Numerical study
Authors: Reinosa José M. , Loureiro A. , Gutiérrez R. , López M.
Published: September 2017

It is a fact, from experimental observations, that all connections used in current practice possess stiffness which fall between the extreme cases of fully rigid or ideally pinned joints. The characterization of the real semi‐rigid behavior of connections must be properly modeled in order to reliably predict the response of the structural frame. The use of bolted cleat angle connections is characterized by substantial economical benefits essentially due to the ease in the erection process. Moreover, this kind of connection enhances both deconstructability and reusability since it preserves the independence of the members. Finally, angle connections are highly recommended for designing in seismic areas instead of welded connections to avoid brittle fracture.

One of the main parameters in connection design is the joint stiffness. The initial stiffness of angle connections could be increased by introducing stiffeners in the joint design. In this paper, numerical a study for the analysis of the rotational stiffness of stiffened angle connections is dealt with. This work was carried through on semi‐rigid angle connections with stiffened top and seat angles. Advanced 3D Finite Element models were developed on the geometrical configuration of future experimental tests. On the other hand, the numerical results of varying the joint configuration are discussed. Once these FE simulations had been checked with the experimental tests, they can be used to undertake future parametric studies on the main joint parameters and also for the validation of analytical proposals that can be very useful in common practice of joint design.
04.02: Plastic behaviour of polygonal hollow sections in bending
Authors: Rohr Katharina , Knoedel Peter , Ummenhofer Thomas
Published: September 2017

Steel poles of polygonal sections are an economic alternative to circular hollow sections for use as lighting towers or transmission line pylons. Especially for transmission lines, the design of the poles is intended to become more compact to avoid land usage and to obtain an inconspicuous appearance. If the pole diameter is reduced, the slenderness of the sections needs to be reduced as well to achieve the desired resistance, but an increasing wall thickness disproportionately reduces the cost‐effectiveness of the structure. The European design rules for overhead electrical lines [1] do not allow using the plastic behaviour of stocky sections, which reduces the advantages of compact sections.

In modern standards for steel structures, such as Eurocode 3 (EC3) [2], activating plastic reserves is generally acknowledged state of the art. According to EC3‐1‐1, the slenderness of the profile decides on the allocation to cross section class 1 or 2, where plastic design is allowed, class 3, where only elastic behaviour is used or class 4, where local buckling is assumed. When changing from class 2 to class 3 sections, this standard provides a sudden drop in resistance, which has long been recognised to be unjustified. Research has been done to overcome this mismatch for circular hollow sections [3].

In this paper the transition between the plastic bending moment capacity and the limit state of buckling is investigated to identify the ultimate load of polygonal sections. The investigated polygon of 16 edges can be treated as a collection of plate strips using the plate buckling design rules EC3‐1‐5 for cross sections class 4. Detailed examinations illustrate the inconsistency of EC3 in the bending capacity of compact sections right before the start of stability problems.

On the basis of experimental data gained from full‐scale bending tests, along with imperfection measurements via laser scanning, numerical investigations have been performed. These results suggest that the bending moment capacity can be increased above the calculated elastic capacity with more compact sections, but might be overestimated when calculating the full plastic capacity according to EC3‐1‐1.
04.06: Post‐buckling strength of plate girders subjected to shear: Experimental verification
Authors: Hansen Thomas
Published: September 2017

This paper describes a calculation method for steel plate girders with transverse web stiffeners subjected to shear. It may be used for predicting the failure load or, as a design method, to determine the optimal amount of internal web stiffeners. The method is based on the theory of plasticity. Many other theories have been developed, but the method presented differs from these theories by incorporating the strength of the transverse stiffeners and by the assumption that the tensile bands may pass the transverse stiffeners, which often is observed in tests. Other methods have only dealt with a single web field between two stiffeners.

The load‐carrying capacity may be predicted by applying both the lower‐bound theorem and the upper‐bound theorem. The upper‐bound solutions have shown very good correlation with existing tests. The emphasis is attached to the presentation of the tests conducted at the Technical University of Denmark. The test programme contained six full scale plate girder specimens. The agreement between the theory and the tests is very good.
04.14: Transfer of axial loads in penstocks: Load carrying behaviour with and without thrust rings
Authors: Ecker Alexander , Unterweger Harald
Published: September 2017

The transfer of axial loads in penstocks to the surrounding concrete and further into the rock was studied within a recently finished research‐project. The traditional way is to use thrust rings for the axial anchorage of penstocks in hydropower‐plants.

A new idea is to transfer the axial loads without thrust rings, only considering friction between the steel pipe and the concrete. This approach is only applicable for the combination of axial loads and internal water pressure.

The Austrian company TIWAG carried out measurements in a part of a newly built penstock without using thrust rings to determine the strains and displacements due to axial loads and internal pressure. The aim was to identify the behaviour due to the axial loads in the pipe and also the friction coefficient between the steel pipe and the concrete, based on additional numerical analyses.

This paper gives an overview of the measurements and the comparison with the accompanying Finite‐Element‐Analysis.

After that in a numerical‐parameter‐study the pipe thickness, the modulus of subgrade reaction of the rock and the friction coefficient between the steel pipe and concrete was varied to get an overview of the behaviour. Within this numerical‐parameter‐study also the load carrying behaviour with additional thrust rings, considering also their axial flexibility, was compared.

Finally a design model for the distribution of the longitudinal stresses in the pipe and for the displacements at the end of the embedded pipe was developed, as a result of the parameter study.

This design model is easy to handle and gives very accurate results for the displacements and the longitudinal stresses of the penstock without thrust rings under axial loads and internal pressure.
04.19: Cost comparison of welded cellular plated square box and cellular shell column structures
Authors: Jármai Károly , Farkas József
Published: September 2017

Cellular plates or shells consist of two layers of plates or shells and a grid of stiffeners welded between them. These structures produce large bending and torsional stiffness using relatively small structural height and thicknesses. In the present study the cellular plates and shells are applied for a cantilever column. They are optimized for minimum cost and compared to each other. The column is constructed as a square box cross‐section with cellular plated walls or a circular cylindrical cellular shell. The column is subjected to a compression and a bending force. It is designed for two special constraints: the horizontal deformation at the top and the width of the column are limited. Both versions are applicable, reducing the plate thicknesses, but the cellular shell performance looks better.
05.06: Design of web‐tapered steel members through a stiffness reduction method
Authors: Kucukler Merih , Gardner Leroy , Macorini Lorenzo
Published: September 2017

Stiffness reduction provides a practical means for the instability assessment of structural steel members. In this paper, a stiffness reduction approach for the design of web‐tapered steel members fabricated through the welding of individual plates is presented. Stiffness reduction functions for welded members, which fully take into account the adverse influence of plasticity and imperfections on the strength and stability, are described. The proposed approach is implemented by (i) dividing the tapered member into prismatic segments along its length, (ii) reducing the flexural stiffness of each segment through the developed stiffness reduction functions considering the withstood forces and the cross‐section properties of each segment, (iii) performing Geometrically Nonlinear Analysis using beam elements and (iv) making cross‐section strength checks. The accuracy of the proposed approach is assessed against the results of nonlinear shell finite element modelling for a large number of tapered members, with various slenderness values, tapering ratios (i.e. the ratios between the cross‐section depths of deep and shallow ends) and loading conditions. It is observed that the proposed stiffness reduction method provides a very accurate and efficient way to design web‐tapered steel members.
05.10: Numerical model for the buckling behaviour of tapered steel members based on experimental tests
Authors: Tankova Trayana , Martins João Pedro , da Silva Luís Simões , Marques Liliana
Published: September 2017

Tapered steel members can provide optimum cross‐section utilization along the member length, which makes them an interesting alternative to prismatic members due to the economy of this solution. However, EN1993‐1‐1[1] does not provide a clear guidance for the stability design of such members. Recently, the authors have provided simplified stability verification methodologies for tapered columns and beams [2, 3]. The developed methodologies are based on analytical derivations which were validated with advanced numerical simulations.

In order to improve the accuracy of the proposed procedures and extend them to members of Class 4 and beam‐columns, an experimental study on tapered columns, beams and beam‐column was carried out. The experiments are used to calibrate a numerical model, incorporating all relevant parameters, such as: geometrical imperfections (local and global) and material imperfections (residual stresses). Unfortunately, the available data on measurements of the material and geometrical imperfections is often found incomplete, even less information is available regarding tapered members. In this paper, firstly a global overview of the experimental programme carried out on web‐tapered steel member is given. The key results from each experiment are summarized; they are further used for the calibration of an advanced numerical model. Finally, an assessment to the magnitude of the adopted geometrical and material imperfections to the member resistance is carried out.
05.19: Lateral‐torsional buckling of steel beams with tapered flanges and web
Authors: Kuś Juliusz
Published: September 2017

Tapered steel beams are commonly applied in modern steel structures due to their less weight and more optimal solutions of the structural designs. That is why effective engineering solutions of the problem of their lateral‐torsional buckling is expected. In the paper a procedure to solve the problem of calculating critical buckling moment of a tapered beam is proposed with the application of potential energy calculations using Ritz method. Respective solution allows to obtain critical moments initiating lateral buckling of the simply supported, modestly tapered steel I‐beams. In particular, lateral‐torsional buckling of beams with tapered flanges and the web are considered. Detailed, numerical, parametric analyses are carried out. Typical engineering, uniformly distributed design loads are considered for load applied to the top flange, shear centre, as well as to the bottom flange. The parametric analysis of beam with tapered cross‐section, demonstrates that tapering of flanges influences much more the critical moments than tapering of the web.
05.20: Modified Ayrton‐Perry formula for flexural buckling of HSS welded box sections
Authors: Kövesdi Balázs , Somodi Balázs
Published: September 2017

The residual stress in steel structural elements has significant influence on the flexural buckling behaviour of compressed members. This phenomenon causes that hot‐rolled, cold‐formed and welded sections with the same geometry have different flexural buckling behaviour and resistance. Previous research results showed that the residual stress pattern of members made from high strength steel (HSS) is different than for normal strength steel (NSS) structures, which results in different flexural buckling behaviour. The current design rules of the EN 1993‐1‐1 [1] for column buckling resistance is based on the Ayrton‐Perry type formula taking the effect of the residual stress and geometric imperfections as generalized imperfections into account. The effect of the residual stress magnitudes is not implemented directly in the method, therefore its implementation could result a more precise column buckling curve, which can differentiate between hot‐rolled, cold‐formed and welded sections, as well as NSS and HSS structures.

The current paper introduces a method, which implements the effect of the residual stress pattern of welded box section columns into the Ayrton‐Perry type formula. This new formulation results in a revised and improved column buckling curve. This new buckling curve is compared to the general buckling curves of the EN 1993‐1‐1 [1] and also compared to recent experimental and numerical results conducted by the authors. The parameters of the improved buckling curve are studied and evaluated in the details. The effect of the magnitude of the residual stress on the buckling resistance is studied and compared to the numerical results. Based on a detailed experimental and numerical research program an improved formulation of the Ayrton‐Perry formula is proposed, which is validated for welded square box sections applicable for NSS and also for HSS grades.
05.25: Lateral torsional buckling investigation on welded Q460GJ structural steel unrestrained singly‐symmetric beams under a point load
Authors: Zhang Yue , Yang Bo , Xiong Gang , Elchalakani Mohamed , Nie Shidong
Published: September 2017

This paper reports the results of experimental tests and parametric analyses for the lateral torsional buckling (LTB) strengths of welded singly‐symmetric I‐shaped cross‐section beams fabricated from Q460GJ structural steel plates. Simply supported beams with varying lengths and sectional dimensions were tested by using a special testing system. In order to achieve the ideal loading condition and the simply supported boundary condition, a special testing system including the and the loading system and supporting system was invented and used in the experimental tests, and the testing system was verified. Meanwhile, a finite element model established by a finite element program ABAQUS, correlated well with the experimental result, was used to conduct the parametric studies. The result showed that the finite element model can be useful in simulation. Thus, the parametric studies were conducted, using the verified finite element model, to investigate the effect of member slenderness and height‐to‐width ratio. It is well known that each design specification has its own background and compiling principles, and the formula of each design code is very difficult. Q460GJ structural steel is a new material, thus, it is very hard to say which design code is more suitable to predict the lateral torsional buckling strengths of welded H‐shaped sectional beams fabricated from Q460GJ structural steel plates. While comparing the test results and the parametric studies results with the prediction of some design code including Chinese design code GB50017‐201X (2012) and GB50017‐2003 (2003), American code (ANSI/AISC360‐10, 2010) and EC3 (2005), some important conclusions can be found. The results demonstrate that the global stability design methods in GB50017‐201X (2012) and EC3 (2005) for rolled sections or equivalent welded sections may be more appropriate for Q460GJ structural steel beams. In addition, the design methods in GB50017‐2003 (2003) and the American code (ANSI/AISC360‐10, 2010) may not be conservative for Q460GJ structural steel beams.
05.39: GBT‐based Finite Element formulation for elastic buckling analysis of conical shells
Authors: Nedelcu Mihai , Mureşan Adina‐Ana
Published: September 2017

The paper presents a finite element formulation based on the Generalised Beam Theory (GBT), for the analysis of elastic buckling behaviour of conical shells under various loading and boundary conditions. The GBT approach provides a general solution for 1st and 2nd order analysis using bar elements capable of describing the global and local deformations. Because of the cross‐section variation specific to conical shells, the mechanical and geometric properties are no longer constant along the bar axis as it is the case of cylinders and prismatic thin‐walled structures. This formulation is validated by comparison between GBT results and values obtained by means of shell finite element analyses. The study covers simply supported and end fixed members, under axial compression.
07.04: Web crippling design of hollow flange channel beams under one flange load cases
Authors: Steau Edward , Keerthan Poologanathan , Mahendran Mahen
Published: September 2017

The advantage of having no unstiffened elements coupled with material located away from the neutral axis makes hollow flange channel (HFC) beam sections structurally efficient in bending when compared with other commonly used open cold‐formed steel sections. This concept is similar to hot‐rolled steel sections such as the universal beam and channel beam sections, which are very efficient in bending. However, the hot‐rolled sections are heavier, torsionally weak, and have low resistance to flexural‐torsional buckling. The two hollow flanges in HFC beams make them torsionally strong and also eliminate the occurrence of distortional and local flange buckling modes in most cases. However, HFC beams have slender webs, making them vulnerable to web crippling failure modes. To understand the web crippling behaviour of HFC beams and develop accurate design rules, finite element models of HFC beams were developed and validated using available experimental results under End One Flange (EOF) and Interior One Flange (IOF) load cases. Using the validated finite element models, a detailed parametric study was conducted for many HFC sections. Finite element analyses provided the required elastic buckling and ultimate loads of HFC beams in web crippling (EOF and IOF load cases). New predictive equations were proposed to determine the elastic buckling coefficients of HFC beams, followed by Direct Strength Method (DSM) based design rules using the test, elastic buckling and nonlinear analysis results from finite element analyses. This paper presents the details of the web crippling design rules developed based on the detailed numerical study on the web crippling behaviour of hollow flange channel beams under one flange load cases.
07.06: Numerical determination of plastic collapse loads for sections under concentrated transverse forces
Authors: dos Santos Gabriel B. , Gardner Leroy , Kucukler Merih
Published: September 2017

Structural steel design codes generally use design methods requiring the determination of two key reference loads: (i) the plastic collapse load and (ii) the elastic buckling load. Using these two key reference loads, the element slenderness can be determined and member resistances can be obtained through buckling curves. Both of these reference loads can be estimated either through simplified analytical expressions or numerical analysis. In the cases of uniform loading, regular geometry and straightforward boundary conditions, the former approach is well suited, while for problems leading to complex non‐uniform stress distributions, such as members under concentrated transverse loading, numerical solutions are often necessary.

Using numerical methods, the plastic collapse loads can be obtained through Materially Nonlinear Analyses (MNA). However, since the development of a plastic collapse mechanism brings about large localised strains and extensive plasticity, a MNA can abort prematurely due to its failure to satisfy the necessary convergence criteria or the obtained load‐deformation path can flatten out only after unrealistically large deformations, resulting in misleading predictions of the plastic collapse loads. In this paper, an extrapolation technique is recommended for the determination of plastic collapse loads from MNA for plate elements and cold‐formed sections under concentrated transverse loading. The proposed procedure is based on the Modified Southwell (MS) Plot, originally proposed for the identification of critical loads.
07.08: Experimental and numerical study of the behaviour of eccentrically loaded cold‐formed channel sections – determination of an optimal load eccentricity
Authors: Merkl Christian , Toffolon Andrea , Taras Andreas
Published: September 2017

Cold‐formed channel sections are often used as bracing elements in storage racking structures, with compressive loading representing a common design condition. The introduction of the compressive force is often carried out through bolted connections in the flanges of the section. Whenever the position of these connection bolts is not precisely aligned with the section's centroid, cold‐formed channel sections are loaded in compression and bending. For fabricators of storage racking systems, it is of economic interest to determine the optimum position of these bolts with respect to the maximum design resistance. However, for eccentrically loaded channel sections, the various parts of the Eurocode provide a series of different rules, which lead to conflicting and contradictory statements regarding the optimal position of the compressive load with respect to the centroid. In this paper, the various code regulations are briefly described and compared – for one exemplary channel section without lips and stiffeners – to the results of a series of non‐linear numerical calculations, as well as to laboratory tests designed specifically to study the effect of eccentricities on the cross‐sectional capacity of channel sections.
07.22: On the use of constrained finite element method in the design of cold‐formed steel Z purlins
Authors: Hoang Trung , Ádány Sándor
Published: September 2017

This paper discusses a potential simple new design approach for cold‐formed steel Z‐purlins. The new design approach tries to simplify the traditional design procedure based on effective widths and thicknesses, which is necessarily complicated due to the complex behaviour of the purlin. The complexity of the behaviour is due to the high slenderness of the purlin member, which makes it prone to various buckling behaviour, as well as due to the typically complicated supports conditions, including elastic restraints from the connecting structural elements. The direct strength method offers an attractive simple alternative for the design, requiring an elastic buckling analysis of the member and then the application of some simple formulae to predict the capacity. The elastic buckling analysis can easily be done by shell finite element method, the only real difficulty being the separation of the characteristic buckling modes such as local, distortional and global buckling. This separation of the modes, however, is now solved by the recently proposed constrained finite element method, which is able to decompose the complex behaviour of virtually any cold‐formed beam or column member, under practically arbitrary loading and support conditions. In the frame of the actual research a potential new, direct‐strength‐based design approach is considered and tested by performing parametric studies on a wide range of Z purlins, by comparing the capacity prediction of the tested alternative method to that of the current Eurocodes. The first results are reported in this paper.
07.26: Structural analysis of C and I shaped cold‐formed steel columns
Authors: Craveiro Helder , Ribeiro João , Breda Ricardo
Published: September 2017

The market share of light steel framing construction using cold‐formed profiles has been increasing significantly in recent years; this solution is now recognized as suitable to be used as primary structural elements, particularly for residential and mid‐rise buildings. One of the main advantages of this construction typology is related to the very low weight of the individual elements which avoids the use of heavy lifting machinery. However, due to the reduced thickness of the individual plates that compose the cold‐formed steel columns (CFS) element cross‐section, CFS are susceptible to local and distortional buckling (or even a combination of both) in addition to the more common global element buckling, which may compromise their load carrying capacity.

This paper explores the behaviour of two distinct CFS cross‐sections under compression, namely a single C section (lipped channel) and a built‐up I section composed of two lipped channels fastened back‐to‐back. The study briefly reports the experimental full scale tests undertaken at the University of Coimbra in order to assess the load carrying capacity of these columns, considering pinned boundary conditions, while comparing it to the design predictions according to the EN 1993‐1‐3; however, the main focus is on the development and validation of a finite element model enabling further parametric studies.

The finite element model is developed with the commercial software ABAQUS using shell elements, and accounts for local, global and distortional geometric imperfections; material non‐linearity is also included based on material characterization previously conducted, and implemented following the Ramberg‐Osgood model. The model is found to be reliable in establishing the buckling loads and the buckling failure modes. A combination of flexural buckling about the minor axis in interaction with distortional buckling at mid‐height of the columns is found to be the main collapse mode, as observed in the experimental tests. The parametric study considers thickness and element length variation.
08.01: Numerical simulation of the load bearing behaviour of concrete dowels in slim‐floor construction – CoSFB
Authors: Braun Matthias , Obiala Renata , Odenbreit Christoph
Published: September 2017

In this paper the current status of an ongoing research on composite slim‐floor beams (SFB) with concrete dowels (CoSFB) is presented, Fig. 1. Using commercial software ABAQUS [1], a 3D solid model with non‐linear material laws has been developed to simulate the load bearing behaviour of concrete dowels numerically. The model was validated by the results of experimental investigations, which have proven a high stiffness of the concrete dowels under service loads and their ductile behaviour in reaching the load bearing resistance [2], [3]. Further, in comparison to traditional shear studs, the thickness of the concrete cover above the upper flange of composite SFB with concrete dowels can be reduced to a minimum, which leads to an optimized floor thickness and overall to a more economic construction. Main parameters defining the FE model, which influence the load bearing capacity, the behaviour and failure of the shear connection were identified and described in this paper. Available results and analysis from the parametric study are described. Wide range of results obtained from the numerical study will be used to derive an analytical model to allow predicting the load bearing resistance of the system.
08.04: Limits of plastic design for composite beams: Requirements for slim and compact composite sections
Authors: Schäfer Markus
Published: September 2017

Due to the demand for sustainable constructions, composite structures become more important and lead to slim and economic solutions. The determination of moment resistance for composite beams follows the rules for composite structures according to EN 1994‐1‐1.

For the plastic design it is still assumed, that each cross‐sectional fibre can plastify without any limitation of strains. For normal composite beams in case of sagging moments and a high‐lying plastic neutral axis, the real moment resistance is slightly higher than the plastic resistance. This is based on the large strains at the bottom side of the section, so that the lower steel flange reaches the solidification range. In case of sections with a large compression zone height xpl, a concrete failure in the compression zone can happen before reaching the plastic moment resistance. In these cases a strain limit design, based on the strain‐stress relationships of concrete and steel, becomes decisive. EN 1994‐1‐1 provides only for cross‐sections of classes 1 and 2 in steel grades S420 and S460 a limitation of plastic design. It is to point out, that the rotation capacity of a composite section is not only conditioned by the b/t ratio of the steel section, but also the concrete part has a significant impact. This applies not only for high steel grades. Though, in Eurocode 4 there are no further regulations given for sections with lower steel grades. Especially, the more and more upcoming integrated and compact composite sections underline the importance of such requirements.

Therefore, the objective of the recent research is concentrated on the development of additional regulations, to consider the influence of concrete compression zone height onto the moment resistance of composite beams.
08.08: Prefabricated demountable concrete and FRP decks in composite structures
Authors: Pavlović Marko , Veljković Milan
Published: September 2017

Welded shear studs are traditionally used to achieve composite actions between steel beams and concrete slabs. Relevance of composite structures for future applications in construction sector is increased by using demountable shear connectors which enables easy reuse of structures. The latest achievements of using demountable bolts embedded in prefabricated concrete slabs as shear connectors are presented in this paper. The focus of the investigation is on possible influence of execution tolerances on the level of composite action. The second issue addressed in the paper is use of Fibre Reinforced Polymer (FRP) composite deck instead of concrete slabs. FRP decks have high strength‐to‐weight ratio which reduce the total weight of the deck. Use of decks which have smaller self‐weight facilitates the transport and execution process and reduces foundation costs especially in high‐rise buildings. FRP composites are used in aerospace, automotive and shipbuilding industries for decades. They are considered as a maintenance free material. The main obstacle for wider applications of FRP material in construction is relatively a low stiffness of composites made of glass fibres and thermoset resins. Use of sandwich systems and hybrid decks, which combine FRP and the steel to increase the stiffness, are investigated in order to satisfy the design requirements. The third item of modern composite structures considered in this paper is use of high strength steel (HSS) grades to optimize the weight/strength ratio of structures. Results of a short parametric study using welded hybrid beams, combination of HSS and mild steel grades, is presented. This indicates significant reduction of weight and costs compared to the design using rolled cross section beams.
08.11: The SMARTCOCO project: A research push for hybrid structures
Authors: Plumier André , Degée Hervé
Published: September 2017

The SMARTCOCO research project was developed to fill gaps in knowledge and provide design guidance for specific types of composite steel concrete structural elements used in high rise or heavily loaded structures. The targeted elements are composite columns reinforced by several fully encased steel sections, columns of reinforced concrete buildings reinforced by one steel section over the height of one storey, without continuity above and under that storey and concrete flat slabs or beams connected to columns or walls by means of steel shear keys. Those composite elements belong to structures defined as “hybrid” because they are neither reinforced concrete structures covered by Eurocode 2, nor composite steel concrete structures covered by Eurocode 4. Gaps in knowledge are mostly related to the way to evaluate the force transmission between concrete and embedded steel profiles and to design the components to resist those forces. A generic design approach based on the logics of composite sections and of reinforced concrete sections, like equivalent sections and struts and ties mechanisms, was first developed and used to design test specimens. These ones were tested in physical and/or numerical experimentations. The results were used to calibrate or correct the initial proposal for design. The output is written as a design guide which intends to complement Eurocode 2 and 4.
08.20: Experimental verification of composite action using push‐out tests
Authors: Kvočák Vincent , Dubecký Daniel , Kožlejová Viktória
Published: September 2017

One of the common types of steel‐concrete composites is the filler‐beam deck bridge with encased steel beams. Steel beams form rigid reinforcement in a longitudinal direction, while such decks are reinforced with secondary cross‐wise reinforcement in a transverse direction. Composite action between the steel and concrete sections is ensured by means of concrete stud connectors. In comparison with the composite action provided traditionally by shear stud connectors, this type of action has higher load‐bearing capacity and fatigue strength, and it is not so labour‐intensive. Great attention is paid to the development of perforated steel strips today. These are employed mainly for the achievement of composite action between a steel beam and concrete slab. To date, a variety of types of composite action have been investigated at the Civil Engineering Faculty of the Technical University of Košice; therefore, the article presented shows some of the test results from push‐out tests performed on various specimens.