Transversally stiffened plate girders subjected to patch loading. Part 1. Preliminary study

In this paper, an experimental programme of six steel plate girders subjected to patch loading as well as results of forty eight numerically-tested prototypes are presented. Results of ultimate load capacity as well as structural responses from these girders are provided. In addition, experimental and numerical values of ultimate load capacity are compared with those predicted by EN1993-1–5. With such results, the response of transversally stiffened steel plate girders is discussed throughout the paper. Particular emphasis is given to the influence of the transverse stiffening on the ultimate load capacity of the girders. It is observed that girders with largely spaced transverse stiffeners present a considerably different response from girders with closely spaced transverse stiffeners. The structural response for the former case has been thoroughly studied in the last decades whereas little attention has been paid for the latter. Further analysis of this particular topic is provided in a companion paper.     

Hybrid steel plate girders subjected to patch loading, Part 2: Design proposal

The resistance of plate girders subjected to patch loading has been studied thoroughly for the case of homogenous girders. The particular case of hybrid girders has been generally treated identically than for homogenous specimens. In this paper, the current EN1993-1-5 formulation is evaluated and some peculiarities concerning the treatment of hybrid girders subjected to patch loading are pinpointed. It is numerically demonstrated that the moment capacity of the flanges does not play any role in the resistance of plate girders to patch loading as predicted in EN1993-1-5. Accordingly, a design proposal which corrects the current EN1993-1-5 formulation is presented at the end of the paper.     

Longitudinally stiffened hybrid steel plate girders subjected to patch loading

Hybrid girders subjected to patch loading have been analyzed in a detailed fashion for the case in which the plates that assemble the girders are transversally stiffened. Scant work, however, is available for the case in which the girders are hybrid and, simultaneously, longitudinally stiffened. The driving force for developing the present research work is to complete the knowledge of the patch loading field for the particular structural alternative of a hybrid steel plate girder assembled with a longitudinal stiffener. In the current paper, a numerical database of 255 simulations on longitudinally stiffened steel girders subjected to patch loading developed by the authors is presented. The results obtained are used for assessing the resistance of longitudinally stiffened hybrid steel plate girders subjected to patch loading. Some discrepancies between the numerical and EN1993-1-5 results are pinpointed. A design proposal which enhances the current EN1993-1-5 formulation is given at the end of the paper.     

剪切作用下锥形板梁的试验和数值研究

对剪切作用下的锥形钢板梁进行了试验和数值研究。试验包含4个缩尺锥形钢板梁试件,主要研究其临界剪切荷载和极限抗剪强度。此外,研究了锥形板的后屈曲特性。另外,对不同几何形状的锥形板进行了参数研究,以找到最有利的设计方案。分析的参数有:板的高宽比、翼缘的倾斜角、腹板和翼缘的长细比。由于性能的不同,对4种类型的锥形板梁分别进行建模和数值模拟。欧洲规范EN1993-1-5给出的锥形板的简化方法证实,在某些情况下,估计的极限剪切强度偏于不安全,需要进行修改。     

Hybrid steel plate girders subjected to patch loading, Part 1: Numerical study

Extensive research focused on the structural behavior of hybrid steel plate girders is nowadays available in the literature. Furthermore, extensive research devoted to the resistance of homogeneous girders to patch loading has been performed in the last decades. Investigations dealing simultaneously with both fields are, however, rather scarce. The driving force behind developing the present research work has been the aim of completing the knowledge of the patch loading field for the particular structural alternative of hybrid steel plate girder. In the current paper, experimental results found in the literature as well as additional numerical simulations developed by the authors are summarized. The results presented can be used for assessing the resistance of hybrid steel plate girders subjected to patch loading. An in-depth exploit of such results is presented in a companion paper.     

折线形腹板钢梁的局部承压性能有限元分析

折线形腹板钢梁是将传统钢梁中的平腹板用折线形钢板来代替,是波纹腹板钢梁的一种。该钢梁具有较高的承载力及良好的经济优势。目前,在国内外仅对梯形腹板钢梁的局部承压性能有少量研究。本文作者采用有限元方法对折线形腹板钢梁局部承压性能进行研究,了解其在实际试验中可能发生的破坏模式和各因素对其局部承压力性能的影响,并为今后试验作准备。     

Transverse stiffeners for plate girder webs—an experimental study

The paper describes nine tests on two large-scale, transversely stiffened plate girders. The objectives of the tests were to determine the ultimate load capacities, to study the modes of failure and, in particular, to investigate the behaviour of the transverse web stiffeners.The results obtained show that the tension field mechanism approach is capable of predicting the ultimate load capacities of girders with widely differing values of web panel aspect ratio, including girders with closely spaced stiffeners. The new design code for steel bridges, BS 5400, is shown to give slightly, but not unreasonably, conservative values of girder capacity.The tests have also shown that the methods currently proposed for the design of transverse web stiffeners are safe but conservative. The detailed observations of stiffener behaviour reported in the paper should facilitate future development of improved methods of stiffener design.     

Finite element investigation of shear failure of lean duplex stainless steel plate girders

The use of duplex stainless steel material has gained popularity in the last two decades thanks to its nature that combines well the advantages of both austenitics and carbon steel materials. The duplex grades offer a combination of higher strength than austenitics in addition to a great majority of carbon steels with similar or superior corrosion resistance. However, high nickel prices have more recently led to a demand for lean duplexes with low nickel content, such as grade EN 1.4162. Wide-ranging work is needed to include the lean duplex grade EN 1.4162, into design standards such as EN 1993-1-4. Accordingly, a finite element modelling for full-size lean duplex stainless steel plate girders of non-rigid end stiffeners of Grade EN 1.4162 is presented in this paper. The paper is principally concerned with shear failure mechanism characteristics of this type of plate girders, which is not yet investigated. The ABAQUS 6.6 programme, as a finite element package, is used in the current work. The lean duplex stainless steel material is simulated here based on an accepted stainless steel material model available in the literature. A number of transversely stiffened I-section plate girders having equal depth of 1000 mm in span of 4 m is considered and parametric studies regarding flange width-to-web depth ratio, flange-to-web thickness ratio and web plate slenderness are carried out. However, new conclusions on shear strength of lean duplex stainless steel plate girders are presented.     

Moment–shear interaction of stiffened plate girders—Tests and numerical model verification

Results of four full-scale tests on plate girders stiffened with transverse and longitudinal stiffeners subjected to interaction of high bending moment and shear force are presented and discussed. In longitudinal direction the web was stiffened with open or closed stiffeners positioned in the compression zone. Detailed information on initial geometric imperfection and residual stresses is given. The experimental results were used to verify numerical model. The resistance is compared against reduced stress method and effective width method given in EN 1993-1-5.     

复合荷载作用下钢梁弯扭屈曲的临界弯矩:(Ⅱ)系数计算及数值算例

基于平面外4种边界约束条件简支钢梁在满跨均布荷载、跨中对称集中荷载和端弯矩作用下,以及平面外4种边界约束条件固支钢梁在满跨均布荷载、跨中对称集中荷载作用下的M_cr三系数(C_1,i、C_2,i、C_3,i)计算式,计算了典型单一荷载工况的M_cr三系数数值,给出了横向荷载与端弯矩共同作用简支钢梁以及横向荷载两两共同作用固支钢梁的复合弯矩系数C_b计算式,通过数值算例验证了本文M_cr三系数和复合弯矩系数计算式的精度。最后对比了本文的M_cr三系数数值与EN 1999-1-1:2007和ENV 1993-1-1:1992中单一荷载的M_cr三系数数值,校验了"4M"等效弯矩系数计算式对简支钢梁、固支钢梁的适用性。结果表明:对于除平面外边界约束条件为R-R(平面外两端简支且约束转动)外的单轴或双轴对称截面简支钢梁以及双轴对称截面固支钢梁,单一荷载的M_cr三系数的数值或计算式以及复合弯矩系数...     

不锈钢薄腹梁受剪性能试验研究

通过对7根不锈钢薄腹梁进行受剪性能试验研究,分析了梁腹板的剪切屈曲和屈曲后强度。结果表明：所有梁均发生剪切屈曲破坏,薄腹板中形成拉力带,上翼缘和横向加劲肋中出现塑性铰;根据腹板表面应变和侧向鼓曲变形测得的剪切屈曲应力均低于理论计算的弹性剪切屈曲应力;梁的受剪承载力显著高于腹板剪切屈曲时的荷载,具有较高的屈曲后强度;梁端设置封头肋板可以提高梁的受剪承载力。基于得出的试验结果及现有其他试验数据,对两种考虑腹板屈曲后强度的受剪承载力计算方法进行评估,我国GB 50017—2017《钢结构设计标准》中的公式仅考虑了腹板的受剪承载力,其计算结果总体偏于保守,但是对腹板高厚比较小(λs<1.5)的不锈钢薄腹梁,受剪承载力计算偏于不安全,且计算结果离散性较大;EN 1993-1-4中的计算公式中同时考虑了腹板和翼缘的受剪承载力,其计算结果偏于保守且离散性较小。     

Openings in horizontally curved plate girder webs

Ultimate strength tests on plate girders curved in plan containing centrally placed circular web openings are reported. Girders, built up of Grade 43A rolled steel plates, were tested to failure and parameters studied include opening size and degree of curvature. Test results show that the ultimate load capacity of the girders dropped linearly with the increasing opening size. Decrease in ultimate load carrying capacity with increasing degree of curvature is also observed for curved girders having smaller web openings. The failure mechanism observed in the tests was similar to that observed in plate girders without web openings, the only difference being the position of plastic hinges on the flange plates. The girders were analysed using the elasto-plastic finite element package, ABAQUS. Comparison of analytical predictions with the experimental results for deflected profiles, ultimate load values and load-deflection relationships show good agreement.     

Experimental behaviour of a thermally restrained plate girder loaded in shear at elevated temperature

This paper outlines an experimental investigation of twelve simply supported steel plate girders subjected to shear loading at elevated temperature. Three different series of steel plate girders have been tested at three constant elevated temperature levels. Additional axial restraints were applied onto beams to simulate the thermal restraint effects of adjacent cooler parts of steel-framed structure in fire. Based on test results and observations, the pre- and post-buckling behaviours of plate girder web panels at high temperature were discussed. In addition, finite element modelling of the web panels was conducted and numerical models generally agreed well with test results. It was observed that the ultimate shear capacity decreased significantly under a thermal restraint effect.     

Shear resistance in stainless steel plate girders with transverse and longitudinal stiffening

This paper summarizes and presents main results of the investigation conducted in the Department of Construction Engineering of the UPC dealing with shear behaviour of stainless steel plate girders. Initial shear buckling stress together with ultimate shear capacity of these structural elements have been evaluated with special attention paid to the effect of including stiffeners, both transverse and longitudinal. The studies conducted, both numerical and experimental tests, have permitted the development of new and simple design expressions to determine more accurately the initial shear buckling stress in stainless steel web panels and the ultimate capacity of plate girders considering the presence of a rigid or non-rigid end post.     

Web openings in horizontally curved composite plate girders

The paper is concerned with the effects of circular or square web openings on the ultimate strength of horizontally curved composite plate girders. Finite element analysis using the computer package LUSAS has been employed to investigate the behavior and ultimate strength capacity of the girders with web openings of different proportions. The opening sizes and their locations within the web panels have been studied in detail, and the results are presented in the form of load–deflection and load–opening size plots. An approximate method to determine the ultimate strength capacity of horizontally curved composite plate girders accounting for the presence of web openings and composite action between the steel girder and concrete slab is presented. The accuracy of the method is established by comparing the predicted strength with the corresponding values predicted by the finite element method.     

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.     

Investigation on the Collapse Behavior of Diagonal Stiffened Composite Plate Girders Subjected to Shear Loading

In this study, a new analytical method is presented to estimate the shear capacity of diagonally stiffened steel–concrete composite plate girders. This method is formulated based on tension field action in steel girder web and failure mechanism of concrete slab deck. To validate the accuracy of the proposed method, the obtained results are compared with three-dimensional finite element analysis of composite plate girders with different configuration of stiffeners. The results of analytical and numerical investigations indicate that the proposed method can accurately estimate the ultimate shear capacity of composite plate girders. In addition, it is shown that the diagonal stiffeners on one hand can reduce the buckling effects of shear panel of girders and on the other hand can increase the strength of elastic shear buckling and ultimate shear capacity of girders well in comparison with the unstiffened thin steel plate girders.     

Ultimate strength of girders with trapezoidally corrugated webs under patch loading

Ultimate strength of steel plate girders with trapezoidally corrugated webs under patch loading is studied using a non-linear finite element method. Effect of large deflection is taken into account and a von Mises material either without strain hardening (elastic-perfectly plastic), or with strainhardening obeying Ramberg-Osgood's equation, is assumed. The following factors that influence the ultimate strength are investigate (1) strainhardening models; (2) initial imperfections (local and global); (3) variation of yield stress and strain-hardening degree at the corrugation corners due to cold forming, ‘corner-effects’; (4) loading position; (S) load distribution length, and (6) variation of geometric parameters. Based upon the numerical results obtained, an empirical formula for the prediction of the ultimate strength is suggested.     

Imperfection sensitivity of plate girder webs subjected to patch loading

This paper is aimed at studying the influence of initial geometric imperfections on the postbuckling behavior of longitudinally stiffened plate girder webs subjected to patch loading. A sensitivity analysis is conducted herein using two approaches (deterministic and probabilistic) in order to investigate the effect of varying imperfection shape and amplitude on both, the postbuckling response and ultimate strength of plate girders under patch loading. This sensitivity analysis is performed by means of nonlinear finite element analysis. At first, the initial shape imperfections are modeled using the buckling mode shapes resulting from an eigenvalue buckling analysis. Thereafter, the amplitude of the buckling shapes for the various modes is varied, and then introduced in the nonlinear analysis. The results show the influence of these modes and amplitudes on the resistance to patch loading.