Journal Of Constructional Steel Research Research Articles

General comments stimulated by three articles on fire behaviour of bridges in the journal of constructional steel research

General comments stimulated by three articles on fire behaviour of bridges in the journal of constructional steel research

NUMERICAL STUDIES ON NON-LINEAR BEHAVIOR OF COMPOSITE STEEL TUBES USING ABAQUS V6.10-1*

In steel and concrete composite construction, the two materials are integrated in structural members to combine the advantages of both materials steel has high strength and ductility and facilitates connections with steel girders and braces in a steel framing system. Concrete is economical, durable and fire resistant. In composite columns, steel tube confines the concrete core leading to an increase in both strength and ductility of the concrete. The concrete core restricts inward local buckling of steel tube. composite columns have been shown to shown to have high strength, stiffness and ductility. As little data is available to justify the structural response, accurate Non-linear static and dynamic computational formulations are required for developing rational system response factors. For developing rational system response factors. Non-linear FEM analysis is performed to quantify demand, optimize design among other purposes. In this dissertation, ABAQUS 6.10-1 and Hyper Mesh is used to study non-linear behavior of composite tubes. At the outset, Validation for the work done by previous researchers(G.Giakoumelias, D.Lam/ Journal of Constructional Steel Research 60(2004)1049-1068) is carried out using nonlinear FEM and is further extendented for experimental work done at the Department of Civil Engineering., R & D laboratory of Ghousia College of Engineering, Ramanagara. Experiments are carried out on columns for different tube thickness, diameter and length, obtained experimental values of ultimate load is compared with EC-4 including ABAQUS results. Frequency in Hz and time period in Sec are also evaluated for different tube sizes, lengths and thickness.

Cold-formed steel structures: Research review 2013–2014

This article reviews research on cold-formed steel structures published in 2013 and 2014 in three leading journals: the Journal of Structural Engineering, ASCE, Thin-Walled Structures and the Journal of Constructional Steel Research. It also reviews papers published in the three main conferences in the area over the same period. These are Eurosteel 2014 (Naples, Italy), the 7th International Conference on Thin-Walled Structures (Busan, Korea) and the 22nd International Specialty Conference on Cold-Formed Steel Structures (St Louis, MO, USA). Three research areas which have recently been incorporated in the North American Specification NAS S100:2012 or are being incorporated in the Australian/New Zealand Standard AS/NZS 4600 have been highlighted. These are the works on the semi-analytical finite strip method for sections in shear by the author and his colleagues at the University of Sydney, net section rupture by Associate Professor Lip Teh at the University of Wollongong and fire design by Professor Mahendran at Queensland University of Technology.

Response to discussion on “Elastic buckling of columns with end restraint effects”

Response Paper to S.E. Djellab's Comments and discussion concerning: R. Adman,M. Saidani, “Elastic buckling of columnswith end restraint effects”, Journal of Constructional Steel Research 87 (2013) 1–5. In what follows is a response to the points of substance made in the discussion paper. The discusser raised issues relating to the rigour and accuracy of the results reported in the original paper. The response below has been presented following the same format adopted by the discusser.

A numerical investigation of local–overall interaction buckling of stainless steel lipped channel columns

A detailed finite element (FE) model is presented, which was developed with the aim of studying the interaction of local and overall buckling in stainless steel columns. The model incorporates non-linear stress–strain behaviour, anisotropy, enhanced corner properties and initial imperfections. The model was verified against a program of 29 laboratory tests on stainless steel lipped channels, described in a companion paper [Becque J, Rasmussen KJR. Experimental investigation of the interaction of local and overall buckling of stainless steel lipped channel columns. Journal of Constructional Steel Research 2009; 65(8–9): 1677–84] and yielded excellent predictions of ultimate strength and specimen behaviour. The FE model was further used in parametric studies, varying both the cross-sectional slenderness and the overall slenderness. Three stainless steel alloys were considered: AISI304, AISI430 and 3Cr12. The results are compared with the governing design rules of the Australian, North American and European standards for stainless steel structures.

General behaviour and effect of rigid and non-rigid end post in stainless steel plate girders loaded in shear. Part II: Extended numerical study and design proposal

After the deep analysis and evaluation of the experimental and numerical results obtained during the described experimental campaign [Estrada I, Real E, Mirambell E. General behaviour and effect of rigid and non-rigid end post in stainless steel plate girders loaded in shear. Part I: Experimental study. Journal of Constructional Steel Research 2005 [submitted for publication]], an extended numerical analysis in code ABAQUS [Hibbit, Karlsson and Sorensen Inc., ABAQUS/Standard, Version 6.3. User’s manual. Rhode Island (USA); 2002] has been carried out dealing with the evaluation of the postbuckling strength in stainless steel plate girders. Finally, a proposal of design expressions for predicting their ultimate shear capacity is made since current design specifications dealing with shear resistance included in Eurocode 3, Part 1–4 [European Committee for Standardisation. ENV 1993-1–4. Eurocode 3: Design of steel structures. Part 1.4: General rules—supplementary rules for stainless steel. Brussels; 1996] have been demonstrated to be overly conservative. Taking special attention of the material non-linearity and the rigid or non-rigid condition of the end post, specimens covering a wide range of slenderness and aspect ratios ( a / d from 0.5 to 3.0) have been numerically tested. Austenitic and Duplex stainless steel grades, which are the most commonly used in construction, have been evaluated during the whole analysis development. Finally, a new design proposal based on the Rotated Stress Field model developed by Höglund [Höglund T. Shear buckling resistance of steel and aluminium plate girders. Thin-Walled Structures 1998;29(1–4):13–30], adequately adapted to the particular features of stainless steel is presented in order to reach a more optimum use of this relatively modern resistant material in construction.

Static tests on steel–concrete–steel sandwich beams

Bi-Steel is an innovative form of steel–concrete–steel sandwich construction invented by Bowerman [Bowerman H, Coyle N, Chapman JC. An innovative steel/concrete construction system. The Structural Engineer 2002;80(20):33–8], in which the two steel plates are inter-connected by a series of transverse bar connectors simultaneously friction welded at both ends. In use, the steel units are assembled, welded, and filled with concrete. The behaviour of the friction-welded bar–plate connections embedded in concrete subjected to bar tension and bar shear have been described in papers [Xie M, Chapman JC. Static and fatigue tensile strength of friction-welded bar–plate connections embedded in concrete. Journal of Constructional Steel Research 2005;61:651–73; Xie M, Foundoukos N, Chapman JC. Experimental and numerical investigation on the shear behaviour of friction-welded bar–plate connections embedded in concrete. Journal of Constructional Steel Research 2005;61:625–49]. This paper presents an experimental investigation on the static behaviour of Bi-Steel beams. Eighteen beams having a range of span, depth, plate thickness and bar spacing, have been tested under static loading, and four elementary modes of failure were observed: tension plate yielding, bar shear, bar tension and concrete shear. The tests confirm that for ductile failure, beams should be designed to fail by yielding of the tension plate. Comparisons are made with current design recommendations and some alternative methods are proposed.

A parametric study for distortional buckling stress on cold-formed steel using a neural network

The process of prediction of distortional buckling stress of cold-formed steel members is often cumbersome and it is also difficult to perform parametric studies in this field to investigate the effect of geometric parameters on Elastic Distortional Buckling Stress (EDBS). To overcome this difficulty a neural network based model and formulation which was presented in a companion paper by the author [Pala M. A new formulation for distortional buckling stress in cold formed steel members. Journal of Constructional Steel Research 2006;62:716–22] is proposed as an alternative approach to investigate the effect of geometric parameters on distortional buckling stress. The model considers the effect of web height, flange width, angle of lip, lip length and flange thickness. The results of the Neural Network model are quite satisfactory and are consistent with the literature.

A parametric analysis of the patch load behaviour using a neuro-fuzzy system

This work presents a parametric analysis to evaluate the behaviour of steel beams subjected to concentrated loads. A neuro-fuzzy system was trained and tested [Fonseca ET. Comportamento de Vigas de Aço Sujeitas a Cargas Concentradas Através de Técnicas de Inteligência Computacional. D.Sc. thesis. Civil Eng. Dept., PUC-Rio. 2003 [in Portuguese]; Fonseca ET, da S. Vellasco PCG, de Andrade SAL, Vellasco MMBR. A neuro-fuzzy system for patch load prediction. In: 7th international conference on the application of artificial intelligence to civil and structural engineering. Egmond aan Zee; 2003 [published in CD-ROM — 18 pages]] to predict patch load results and classify this behaviour. In preceding studies [Fonseca ET, Vellasco MMBR, da S. Vellasco PCG, de Andrade SAL, Pacheco MAC. A neural network system for patch load prediction. Journal of Intelligent and Robotic Systems 2001;31:185–200; Fonseca ET, da S. Vellasco PCG, de Andrade SAL, Vellasco MMBR. A patch load parametric analysis using neural networks. Journal of Constructional Steel Research 2003;59(2):251–67; Fonseca ET, da S. Vellasco PCG, de Andrade SAL, Vellasco MMBR. Neural network evaluation of steel beam patch load capacity. Advances in Engineering Software 2003;34(8):680–705] the performance of neural networks was significantly more accurate than patch load prediction formulae [Lyse I, Godfrey HJ. Investigation of web buckling in steel beams. In: ASCE Transactions, vol. 100, 1935, p. 675–95 [paper 1907]; Bergfelt A. Patch loading on slender web. Influence of horizontal and vertical web stiffeners on the load carrying capacity, Chalmers University of Technology, Publication. S79:1, Goteborg, 1979, p. 1–143; CISC, Canadian Institute of Steel Construction. Limit states design of steel structures. CAN/CSA -S16-01; 2001; Eurocode 3, ENV-1993-1-1. Design of steel structures. CEN, European Committee for Standardisation; 1997 [Doc. CEN/TC 250/SC3-N419E]; Roberts TM, Newark ACB. Strength of webs subjected to compressive edge loading. Journal of Structural Engineering, American Society of Civil Engineers 1997;123(2):176–83], although the system did not consider the difference in the beam ultimate limit state. Therefore this paper applies a neuro-fuzzy system to evaluate the ultimate load physical phenomena (yielding, buckling or crippling) as well as the critical load related to each collapse type.

Semi-rigid composite frames with perfobond and T-rib connectors Part 2: Design models assessment

This paper proposes a new design and construction system for composite semi-rigid portal frames. The system uses a perfobond shear connector and a T-rib connection element for composite action. Tests confirmed that the connector’s structural behaviour is compatible with the proposed structural solution [Ferreira LTS, de Andrade SAL, da S Vellasco PCG. A design model for bolted composite semi-rigid connections. In: Stability and ductility of steel structures. Elsevier; 1998. p. 293–306; Ferreira LTS, de Andrade SAL, da S Vellasco PCG. Composite semi-rigid connections for edge and corner columns. In: Eurosteel, 2nd European conference on steel structures. 1999]. Based on these results this paper presents two design models for bolted composite semi-rigid connections based on simple force paths. The models’ performances were validated through comparisons with experimental results in terms of moment–rotation curves, as well as initial stiffness and rotation capacity [da S Vellasco PCG, de Andrade SAL, Ferreira LTS, de Lima LRO. Semi-rigid composite frames with perfobond and T-rib connectors — Part 1: Full scale tests. Journal of Constructional Steel Research 2005 [submitted for publication] doi:10.1016/j.jcsr.2006.04.011; Ferreira LTS. Avaliação de ligações semi-rígidas mistas aparafusadas. Ph.D. thesis. Civil Engineering Department, PUC-RIO, 2000 [in Portuguese]. [4]]. Finally, an evaluation of the actual stresses present in the tested composite frames and design models is presented based on experimental strains obtained in the connection and composite section key points.

Interaction formulae for members subjected to bending and axial compression in EUROCODE 3—the Method 2 approach

The final version of EN1993-1-1, EUROCODE 3 [EN1993-1-1. Eurocode 3. Design of steel structures, general rules and rules for buildings. 2005] for Steel Structures provides two alternatives for the buckling check of members subjected to axial compression and bending by interaction formulae, which are called there Method 1 and Method 2. This paper presents the characteristics, the background and the use of Method 2. The analogous presentation of Method 1 has already been given in [Boissonnade N, Jaspart J-P, Muzeau J-P, Villette M. New Interaction formulae for beam-columns in Eurocode 3. The French-Belgian approach. Journal of Constructional Steel Research 2004;60;421–31]. The Method 2 formulae have been derived on the basis of the general format of the interaction concept of existing codes, e.g. the ENV-rules; however with advanced numerical background and consistent classification of the buckling modes. In this respect new improved interaction factors were developed from a wide scope of numerical simulations and the concept of the formulae was focussed distinctly on describing the modes of in-plane and out-of-plane buckling for members susceptible to fail either in flexural buckling or in lateral–torsional buckling. As result two sets of formulae are provided, which each cover a clear scope of physical member behaviour. Hereby, the specific effects of intermediate lateral restraints—as often found in steel structures—have also been included. The Method 2 formulae aim at providing buckling rules with compact simplified interaction factors and transparent application for standard cases.

Further study on the flexural behaviour of concrete-filled steel tubes

This paper is a further study on the flexural behaviour of concrete-filled steel tubes based on the former work presented by Han [Han LH. Flexural behaviour of concrete-filled steel tubes. Journal of Constructional Steel Research 2004;60(2):313–37]. A total of 36 composite beam specimens filled with self-consolidating concrete (SCC) were tested. The main parameters varied in the tests are: (1) sectional types (circular and square); (2) steel yielding strength (from 235 to 282 MPa); (3) the ratio of tube diameter (or width) to wall thickness, D / t (from 47 to 105), and (4) the ratio of shear span to depth (from 1.25 to 6). Comparisons are made with predicted beam capacities using the existing methods, such as AIJ-1997 [Architectural Institute of Japan (AIJ). Recommendations for design and construction of concrete filled steel tubular structures. 1997], AISC-LRFD-1999 [AISC. Load and resistance factor design specification for structural steel buildings. Chicago: American Institute of Steel Construction, Inc.; 1999], BS5400-1979 [British Standard Institute: BS5400, Part 5, Concrete and composite bridges. 1979], EC4-1994 [Eurocode 4. Design of composite steel and concrete structures, Part 1.1: General rules and rules for buildings (together with United Kingdom National Application Document). DD ENV 1994-1-1:1994. London W1A2BS: British Standards Institution; 1994] and the method proposed by Han [Han LH. Flexural behaviour of concrete-filled steel tubes. Journal of Constructional Steel Research 2004;60(2):313–37]. Applied calculation formulae of moment versus curvature curves and the flexural stiffness of concrete-filled steel tubular (CFST) beams are presented, based on the mechanics model of Han [Han LH. Flexural behaviour of concrete-filled steel tubes. Journal of Constructional Steel Research 2004;60(2):313–37]. Comparisons are made with predicted beam flexural stiffness using different methods, such as AIJ-1997, AISC-LRFD-1999, BS5400-1979, EC4-1994 and the method proposed in this paper. Comparisons are also made between the simplified model and the mechanics model, and generally good agreement is achieved.

Lateral–torsional buckling resistance of coped beams

The lateral–torsional buckling resistance of beams depends on the support conditions. In floor structures for buildings coped beams are often used. A numerical model was developed to investigate the influence of copes on the lateral buckling resistance. This model is described in a companion paper [Maljaars J, Stark JWB, Steenbergen HMGM, Abspoel R. Development and validation of a numerical model for buckling of coped beams. Journal of Constructional Steel Research 2005;61(11):1576–93]. In this paper results of a parameter study carried out with the numerical model are presented. Based on these results recommendations for design rules are given. The study is restricted to (coped) beams with end plates.

Development and validation of a numerical model for buckling of coped beams

The lateral torsional buckling resistance of a beam depends on the support conditions. In structures for buildings, coped beams are often used. A numerical model is developed to investigate the influence of copes on the lateral buckling resistance. The model was verified with laboratory tests. This paper describes the background of the numerical model, the test program and the results of the validation. In a companion paper [Maljaars J, Stark JWB, Steenbergen HMGM, Abspoel R. Lateral–torsional buckling resistance of coped beams. Journal of Constructional Steel Research 2005;61(11):1559–75], the results of a parameter study are presented.

Experimental and numerical investigation on the shear behaviour of friction-welded bar–plate connections embedded in concrete

Friction-welded bar–plate connections are a basic structural component of Bi-steel steel–concrete–steel sandwich construction. In Bi-steel members, the bar–plate connections, embedded in concrete, are subject to tension, shear and bending. The static and fatigue behaviour of the embedded connections subjected to bar tension is described in another paper [Xie M, Chapman JC. Static and fatigue tensile strength of friction-welded bar–plate connections embedded in concrete. Journal of Constructional Steel Research [in press]]. This paper presents experimental and numerical studies on the static behaviour of the friction-welded connections with the bar loaded in shear. Finite element analysis is carried out to examine the effects of variations in geometric and material parameters. The experimental results are used to derive an empirical equation for predicting the shear strength of embedded connections, and compared with existing test results and code specifications. Further papers will describe fatigue behaviour of the embedded connections subjected to bar shear, and static and fatigue tests on Bi-steel beams.

Sensitivity analysis of the stability problems of thin-walled structures

Analysing the system behaviour in relation to the input quantities it is often necessary to find out what quantities have the greatest effect on the studied output. The article shows the essential methods of applied sensitivity analysis. The objective of the paper is to analyse the influence of initial imperfections on the resistance of a member under axial compression. The analysis uses the Latin Hypercube Sampling simulation method (LHS) [Novák D, Teplý B, Shiraishi N. Sensitivity analysis of structures. In: Proc. of the fifth int. conference on civil and structural engineering computing. 1993. p. 201–07; Novák D, Lawanwisut W, Bucher C. Simulation of random fields based on orthogonal transformation of covariance matrix and Latin hypercube sampling. In: Proc. of int. conference on Monte Carlo simulation. 2000. p. 129–36] together with advanced models based on the nonlinear beam finite element method. The histograms of initial imperfections obtained by measurement [Melcher J, Kala Z, Holický M, Fajkus M, Rozlívka L. Design characteristics of structural steels based on statistical analysis of metallurgical products. Journal of Constructional Steel Research 2004;60:795–808] were considered.

Discussion of “Full-range stress-strain curves for stainless steel alloys” [Journal of Constructional Steel Research 2003;59:47–61

Discussion of “Full-range stress-strain curves for stainless steel alloys” [Journal of Constructional Steel Research 2003;59:47–61

Fracture strength of a moment resisting welded connection under combined loading: Part II—Results

The Northridge fractured connections have been so far studied in relation to the weld's material properties. Upon recognition of the fact that the weld forms only part of the entire connection and that column material properties also need to be addressed, Part I, (Righiniotis TD, Lancaster ER, Hobbs RE. Fracture strength of a moment resisting welded connection under combined loading. Part 1—Formulation. Journal of Constructional Steel Research 2000:56(1):17–30), presented the formulation which determines the stress intensity factors for a column with a cracked flange when the former is subjected to tension, bending, stress concentrations and welding residual stresses. In this paper the results of this formulation are put forward and the fracture strength of specific Northridge connections is considered.

Evaluation of partial safety factors γM of composite beams

Taken from the Journal of Constructional Steel Research, 1998, 46:1-3, Paper No. 313. -------------------------------- In this paper, the approach for the determining of partial safety factors gc and ga for composite beam in sagging bending was processed. The statical system is a simple supported beam. The cross-section is composed of hot-rolled I-section and a solid concrete slab with normal-density concrete. There were beams with full shear connection and stud head connectors. The modified approach of Johnson , Huang 1994 is based on existing approaches for steel components used in the drafting of the Eurocode 3 codes. Research was carried out on the basis of 33 test results of composite beams in four different laboratories. The partial model resistance factor grd and the correction term for calculation resistance model bi are expresses according to the position of the neutral axis xpl. The greatest uncertainties in the models, as well as in the correction term for the test specimen, was usually in the neutral axis in the concrete slab close to the upper edge. This data could be important in approaches of calibration of composite structures if they can be proven for an extensive number of test results. The obtained values of partial safety factors for concrete and steel have been commented on from the aspect of calibration of composite structures in the Republic of Croatia.

Safety indices obtained by calibration of existing steel structures in Croatia

Taken from the Journal of Constructional Steel Research, 1998, 46:1-3, Paper No. 088. -------------------------------- The selection of target safety indices for particular classes of structures should be made on the national level of every country. It is necessary that such a selection is made because of different technical achievements and economic potentials. Before decisions on adoption of target values have been made, safety levels of the existing structures should be determined. Such a procedure is called calibration. The selection of safety level poses a serious problem. Any requirement that is too high can cause economic or social problems. The Ministry of Science and Technology of the Republic of Croatia has funded a project titled � Safety degree harmonization of steel structures in Croatia.� Some results that were obtained during the probabilistic calibration in Croatia are in the following field: fatigue of railway steel bridges, composite structures, thin-walled structures and sandwich element. The results obtained can serve for harmonizing safety levels of particular classes of structures. Besides, the results can be used for preparing National Application Document (NAD) in applying Eurocode to the national standard.