Intermediate Transverse Stiffeners Research Articles

Shear buckling resistance and intermediate transverse stiffeners internal forces of full-scale steel plate girders – Experimental tests and numerical investigation

This paper presents the results from two full-scale transversally stiffened plate girder’s load tests in shear and bending. The plate girder’s internal stiffener forces and shear buckling resistance are estimated using the web and stiffener measured strains. These results show that the reported axial compression and bending moment of the intermediate transverse stiffeners for the tested plate girder are 70% of the FprEN 1993–1-5: 2022 [1] design force. The two full-scale plate girders fail due to buckling shear. Nonlinear FEM analyses based on the test girder geometry, measured initial geometric imperfections, and the material properties from the tensile tests, show excellent agreement with the test results, with less than 5% on the maximum applied forces and related displacements. The principal membrane stresses path that triggers the failure of the web plate are investigated based on numerical results and compared with the test measurements. Contrary to the assumption of a rotated stress field model, the principal compression stress obtained in the experimental test was higher than shear buckling stress in the vicinity of the intermediate transverse stiffener.

Numerical study on steel plate girders ‐ Intermediate transverse stiffeners axial force

AbstractTransverse stiffeners are used in steel plate girders with slender webs to provide lateral support to the web along the span and thus increase the plate girder shear resistance. Furthermore, transverse stiffeners anchor the tension field, resulting in axial compression in the stiffener. Despite this, it is widely assumed that the design axial force provided by the FprEN 1993‐1‐5 [1] for the transverse stiffeners is significantly greater than that observed in experimental testing and numerical simulations.The results of 550 nonlinear numerical simulations of plate girders loaded in shear up to failure are presented. Shear resistance and axial stiffener forces are evaluated while the effects of a wide parameter range as web aspect ratio and thickness, flange‐to‐web area ratio, and steel grade are investigated. The numerical results are compared to the European standard design values. Finally, a statistical analysis of the set of results is presented.The numerical analyses show that the axial forces installed in the intermediate transverse stiffeners are significantly lower than those specified by FprEN 1993‐1‐5 [1].

Experimental behaviour of plate girders in steel – Internal forces in intermediate transverse stiffeners

Economical design of steel plate girders usually adopts slender web panels sometimes combined with large panel aspect ratio, which determines the elastic stability of the web panel. The adoption of transverse stiffeners is one efficient strategy to retard the web buckling due to shear. The primary role of intermediate transverse stiffener is clear: divide the web into panels providing lateral support to the web plate along the span – This increases the shear strength of the web. However, FprEN 1993-1-5: 2022 [1] stiffener design approach is based mainly on direct compressive forces resulting from the tension filed action in post buckling phase. According to multiple investigations, this area requirement is much higher than that found in laboratory testing and numerical simulations. The findings of experimental testing on eight plate girders with thin webs and two configurations of transverse stiffeners under ultimate load are presented. Using the web and stiffener measure strains, the internal stiffener forces are calculated past the shear failure of the plate girders. These results show that the axial compression and bending moment measured in the intermediate transverse stiffeners are considerably lower than those specified for the design by the FprEN 1993-1-5: 2022 [1].

Behaviour of Plate Girders with Intermediate Transverse Stiffeners – Experimental Investigation

AbstractTransverse stiffeners are used in slender steel plate girders along the span to give web lateral support and increase plate girder shear resistance. According to several studies, transverse stiffeners are primarily engaged in out‐of‐plane bending to laterally limit the edges of the panel as it buckles, rather than axial compression to anchor the tension field. As a result, the axial loading defined in EN 1993‐1‐5 [1] for the design of transverse stiffeners, based on tension field action, is usually deemed to be substantially larger than that observed in laboratory testing and numerical simulations. The test results of six plate girders loaded to failure, with slender webs and two transverse stiffener geometries, are presented. FE‐models that accurately replicate the tests provide a thorough view of the plate girder behaviour. The stiffeners internal forces are evaluated during plate girder loading up to failure. The transverse stiffener internal forces attained by both models are compared. It is confirmed that both the axial compression and the bending moment in the intermediate transverse stiffeners are much lower than the values prescribed by the EN 1993‐1‐5 [1].

Finite Element Analysis on Shear Strength of a Castellated Beam with Hexagonal Web Opening

A beam (flexural member) with several regular openings with different shapes is called a castellated beam. The castellated beams are well accepted in the industry, multi-story buildings, and power plants due to their increased depth of the section along with the web results in increased strength and stiffness. Though numerous simulation and experimental analyses have been made on the castellated beam, with intermediate transverse stiffener, bearing stiffener and torsion stiffener are used to increase a load-bearing capacity of the beam, but the study on the understanding of diagonal stiffener in the opening is very meager. The objective of the research is to investigate the linear behavior – ISMB150 and IC225 castellated beam of hexagonal openings with and without diagonal stiffeners and the effect of fillet radius at the corner of the openings is studied. Using finite element analysis software,Hyper works, with OptiStruct as a solver, under simply supported beam construction with four-point loading conditions was analyzed by developing an efficient 3D model for the analysis. Due to the openings in the section, the sharp corner of the opening is subjected to Vierendeel failure by the formation of plastic hinges at the corners, which makes critical hence by providing diagonal stiffener in the direction of diagonal tension and diagonal compression for the smooth flow of shear forces. The results show an improvement in load-bearing capacity of 1.51 times in the castellated beam than the parent section ISMB150. The stiffener provided further enhances the same to 1.45 times compared to the ISMB150 section. The linear results show lesser stress concentrations at the web opening corners, thus reducing the prominence of failure at the corners.

Intermediate transverse stiffener requirements of high-strength steel plate girders considering postbuckling capacity

The postbuckling capacity of HSS plate girders is larger than that of mild steel plate girders because of the differences in material properties. Hence, to fully develop the postbuckling capacity, the intermediate transverse stiffener requirement of HSS plate girders could be different from that of mild steel plate girders. The plate girders concerned in this study are without a longitudinal stiffener. To investigate the aforementioned issue, the minimum moment of inertia requirements of intermediate transverse stiffeners in HSS and mild steel plate girders are studied through the finite element analysis (FEA). After the comparison between the FEA results and the results from the design equations in AASHTO LRFD, it states that the design equations in AASHTO LRFD could not be directly used in the design of intermediate transverse stiffeners in HSS plate girders. Hence, based on the FEA results, a new equation is proposed to predict the minimum moment of inertia requirement of intermediate transverse stiffeners in HSS plate girders. Furthermore, because of the difference in the resistant capacity between HSS and mild steel plate girders, the maximum additional out-of-plane deflection of the intermediate transverse stiffener in HSS plate girders corresponding to the ultimate shear resistance is significantly larger than that of the intermediate transverse stiffener in mild steel plate girders. Hence, there is a noteworthy adverse effect caused by the additional out-of-plane deflection of the intermediate transverse stiffener on the shear resistance of HSS plate girders with the maximum limit value set.

Nelinearna analiza vitkih čeličnih greda

U radu je provedena analiza ponašanja tankostjenog hrpta neukrućene zavarene grede na utjecaj jednoliko raspodijeljenog vertikalnog opterećenja. Izrađen je numerički model grede u programskom paketu ABAQUS. Cilj ovog rada je dobiti vjernu numeričku simulaciju ponašanja grede u usporedbi s laboratorijski ispitanom gredom čiji su rezultati ispitivanja preuzeti iz literature te analizirati pojavu izbočivanja u zoni panela hrpta. Provedena je linearna analiza kojom su određeni vlastiti oblici izbočivanja grede te nelinearna analiza kojom su određene vrijednosti deformiranja grede. Na kraju je dana usporedba rezultata dobivenih numeričkim simulacijama s rezultatima laboratorijskog ispitivanja.

Design of intermediate transverse stiffeners for shear web panels

The function of intermediate transverse stiffeners attached on plate girder web panels is to provide simple supports so as to reduce the panel aspect ratio, thereby increasing the shear buckling strength. This study investigates the moments of inertia of the transverse stiffeners required to maintain the simple support condition not just for elastic buckling but also for postbuckling through linear buckling and nonlinear finite element analyses. From nonlinear regression analyses of the FEA results, a set of design equations are formulated and compared with the current provisions in AISC and AASHTO LRFD specifications. It is found that the design equation for elastic buckling in AISC and AASHTO LRFD specifications is too conservative especially when the aspect ratio is greater than 1.0. Also, the design equation for postbuckling in AISC and AASHTO specifications results in designs that are too conservative due to oversimplification.

Integrated Design and Numerical Simulation of Stiffened Panels Including Friction Stir Welding Effects

Stiffened panels are usually the basic structural building blocks of airplanes, vessels and other structures with high requirements of strength-to-weight ratio. They typically consist of a plate with equally spaced longitudinal stiffeners on one side, often with intermediate transverse stiffeners. Large aeronautical and naval parts are primarily designed based on their longitudinal compressive strength. The structural stability of such thin-walled structures, when subjected to compressive loads, is highly dependent on the buckling strength of the structure as a whole and of each structural member. In the present work, a number of modelling and numerical calculations, based on the Finite Element Method (FEM), is carried out in order to predict the ultimate load level when stiffened panels are subjected to compressive solicitations. The simulation models account not only for the elasto-plastic nonlinear behaviour, but also for the residual stresses, material properties modifications and geometrical distortions that arise from Friction Stir Welding (FSW) operations. To construct the model considering residual stresses, their distribution in FSW butt joints are obtained by means of a numerical-experimental procedure, namely the contour method, which allows for the evaluation of the normal residual stress distribution on a specimen section. FSW samples have been sectioned orthogonally to the welding line by wire electrical discharge machining (WEDM). Displacements of the relaxed surfaces are then recorded using a Coordinate Measuring Machine and processed in a MATLAB environment. Finally, the residual stress distribution is evaluated by means of an elastic FE model of the cut sample, using the measured and digitalized out-of-plane displacements as input nodal boundary conditions. With these considerations, the main goal of the present work will then be related to the evaluation of the effect of FSW operations, in the ultimate load of stiffened panels with complex cross-section shapes, by means of realist numerical simulation models.

Intermediate transverse stiffeners in plate girders

AbstractThe aim of this paper is to study the design requirements for rigid intermediate transverse stiffeners in longitudinally stiffened plate girders. Firstly, two representative design codes, AASHTO and EN 1933‐1‐5, are discussed and compared. Then the results of two tests on 1.5 m deep plate girders and the results of the extensive numerical parametric study are presented. The analysis of the results shows that the axial force in the stiffener due to tension field action is overestimated in the design codes and that all the design requirements for rigid transverse stiffeners can be covered by defining a minimum required second moment of area.

A study into optimization of stiffeners in plates subjected to shear loading

A great deal of attention has been focused on plates subjected to shear loading over the past decades. One main fact in design of such elements, which fall in the category of thin-walled structures, is their buckling behavior. Plate girders and recently shear walls are being widely used by structural engineers, as well as ship and aircraft designers. The role of stiffeners is proved to be vital in design of such structures to minimize their weight and cost. In this work, by using ANSYS finite element method of analysis, some 1200 plates are analyzed in order to study the role of stiffeners and to come up with some limits for an optimized design procedure. This eigenvalue method of analysis is first validated with the theoretical calculations and known cases for a wide range of typical panel geometries. The results show that the number of panels produced by intermediate transverse stiffeners should not be less than the value of plate's aspect ratio. In other words, the transverse stiffeners should divide the length of the plate to portions equal or less than its width. It is also shown that the optimum geometric properties of the stiffeners correspond to the point when the buckling shape of a plate changes from the overall mode to local mode. Furthermore, all stiffened plates, with a similar aspect ratio and number of stiffeners, have a specific value of EI s/ aD, for which the critical shear stress is optimal. In addition, some expressions to predict these properties are presented.

Errata for “New Design Rule for Intermediate Transverse Stiffeners Attached on Web Panels” by Sung C. Lee, Chai H. Yoo, and Dong Y. Yoon

Errata for “New Design Rule for Intermediate Transverse Stiffeners Attached on Web Panels” by Sung C. Lee, Chai H. Yoo, and Dong Y. Yoon

New Design Rule for Intermediate Transverse Stiffeners Attached on Web Panels

The equation for the required area of the intermediate transverse stiffener stipulated in the current AASHTO and AISC specifications was derived under the assumption that the transverse stiffener is subjected to an axial compression resulting from diagonal tension developed in the postbuckling stage as noted by Basler in 1963. However, the area requirement is known to be overly conservative. A recent study by Lee et al. in 2002 reported that the transverse stiffener is not necessarily subjected to an axial compressive force during postbuckling of the web panel and hence the current area requirement can be eliminated. The study also reported that the flexural rigidity should be increased several times higher than that required for elastic shear buckling in order for the web panel to develop its potential ultimate shear strength. In the present study, an experiment was conducted in order to investigate the behavior of the transverse stiffeners during postbuckling. The test results confirmed the earlier find...

Behavior of Intermediate Transverse Stiffeners Attached on Web Panels

Current AASHTO and AISC specifications require that an intermediate transverse stiffener attached on the shear web panel be designed not only to have a proper bending rigidity to meet the simply supported condition when the web panel buckles, but to have a proper area in order to resist the compression developed due to diagonal tension in the postbuckling range as well. However, the equation for the required areas, which was suggested by Basler in 1963 has been known to be conservative. According to recent studies, Basler’s assumption for the formulation of the design equation appears to be questionable. In this paper, the behavior of the transverse stiffeners is investigated through a three-dimensional nonlinear finite element analysis. This finite element analysis gives results that are contrary to Basler’s questionable assumption. The transverse stiffener is not necessarily subjected to axial compression in the postbuckling stage, and therefore, the requirement for the minimum areas can be voided. A shear transfer model called “shear cell analogy” is presented in order to describe the postbuckling behavior of the shear web panel in a manner different from those in the literature to date. This analogy is also used to explain why axial compressive stresses do not develop in the transverse stiffeners.

A PROPOSITION FOR DESIGNING INTERMEDIATE TRANSVERSE STIFFENERS IN WEB PLATE OF HORIZONTALLY CURVED GIRDERS

This paper presents an analytical study on the ultimate strength of intermediate transverse stiffener in the web plate of horizontally curved girders. Firstly, the shear buckling strength is analyzed by the theory of shallow shell. Secondly, the ultimate shear strength is also inquired through the collapse model. Based upon these analyses and some experimental data, the behaviors of the transverse stiffener are discussed. Finally, a beam-column model for evaluating the strength of the transverse stiffeners is proposed and a design recomendation to determine the strength and corresponding rigidity of the transverse stiffeners of curved girders in the ultimate state is given by this paper.

Shear Buckling of Clamped and Simply–Supported Infinitely Long Plates Reinforced by Transverse Stiffeners

SummaryThe paper presents a solution to the buckling of infinitely long plates clamped along the edges, together with an extension of the solution obtained by Stein and Fralich for the case when the edges are simply-supported. It is shown that, as a consequence of increasing the edge support from that of a simple support to one in which both deflection and rotation are prevented, the rigidity which an intermediate transverse stiffener must possess in order to support the plate effectively is much reduced. Agreement between the theoretical relationships and existing experimental data is good.