bluuebunny/crossref_metadata_2025_split huggingface dataset:
04.14: Transfer of axial loads in penstocks: Load carrying behaviour with and without thrust rings
Authors: Ecker Alexander , Unterweger Harald 
Published: September 2017

ABSTRACTThe 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

ABSTRACTCellular 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

ABSTRACTStiffness 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

ABSTRACTTapered 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

ABSTRACTTapered 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

ABSTRACTThe 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

ABSTRACTThis 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

ABSTRACTThe 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

ABSTRACTThe 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

ABSTRACTStructural 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

ABSTRACTCold‐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

ABSTRACTThis 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

ABSTRACTThe 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

ABSTRACTIn 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.