This is a repository copy of Vierendeel Bending Study of Perforated Steel Beams with Various Novel Web Opening Shapes , through Non-linear Finite Element Analyses (original) (raw)
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The Journal of Structural Engineering-ASCE, 2011
The Vierendeel mechanism is always critical in perforated steel beams with single large web openings, where global shear forces and Vierendeel moments co-exist. Thus far, the main parameters that are known to affect the structural behavior of such beams are the depth of the web opening, the critical opening length of the top tee-section and the web opening area. A comprehensive Finite Element (FE) study of four sizes of perforated steel sections with three different sizes of eleven standard and novel non-standard web opening shapes was undertaken, and their primary structural characteristics presented in detail in order to provide a simple design method for general practice. The different geometric parameters were isolated and studied in order to understand the significance of their effects and in turn advance the knowledge on the performance of perforated steel beams. An elaborate FE model was established, with both material and geometrical non-linearity, allowing load redistribution across the web openings and formation of the Vierendeel mechanism. The reduction of the global shear capacities, due to incorporation of the local Vierendeel moments acting on the top and bottom tee-sections, was obtained directly from the FE analysis. Following that, a comparison of the global shear-moment (V/M) interaction curves of the steel sections with various web opening shapes and sizes was established and empirical generalized V/M interaction curves developed. Moreover, the accurate position of the plastic hinges was determined together with the critical opening length and the Vierendeel parameter. This work has now shown that the shape of the web opening can also significantly affect the structural behavior of perforated beams, as opposed to the equivalent rectangular shape predominately used so far. In addition, the effect of the position of the web opening along the length of the perforated beam was revealed. The importance of the parameters that affect the structural performance of such beams is illustrated. The thorough examination of the computational results has led to useful conclusions and an elliptical form of a web opening is proposed for further study. The outcome of this study is considered as being relevant for practical applications.
Optimisation of Novel Elliptically-Based Web Opening Shapes of Perforated Steel Beams.
The Journal of Constructional Steel Research, 2012
A new study was carried out and presented herein, on the optimisation of novel elliptical-based web opening shapes which enhance the structural behaviour of the perforated beams as well as lead to economic design in terms of both manufacture and usage. The finite element (FE) model used in the study was validated against experimental work conducted by the authors and the results of the comprehensive study are presented in this research paper. For ease of comparison, the yield patterns and deflected shapes of the perforated beams are presented at three characteristic load level points. Finally, shear-moment interaction FEM curves are presented for six different web opening shapes to allow for easy use of the empirical design formulas that have previously been proposed by the authors in a complementary research paper. An overall study of many standard and non-standard web opening shapes, it was shown that perforated beams with vertical and inclined elliptical web openings (3:4 width to depth ratio) behave more effectively compared to perforated beams with conventional circular and hexagonal web openings, mainly in terms of stress distribution and local deflection. Therefore, perforated steel beams with large novel elliptically-based web openings with short critical opening length at the top and bottom tee-section as well as straight-line edges are presented for first time and examined in the current research programme.
The Journal of Constructional Steel Research, Vol. 67, Issue 10, 2011, pp. 1605-1620
The use of perforated steel beams has resulted in longer span floors. Their popularity has also increased because of an architectural emphasis on exposed structures, with cellular, castellated and elongated web openings being typical in structural sections. Sections having webs penetrated by large closely spaced openings over almost the full span are now common. Although the best application of these beams appears to be for long spans which are to carry a light uniform load, some heavy-mass structures, such as bridges, have been constructed using perforated beams for the full span. Also, with greater automation, the cost of their fabrication has been reduced to the level where for certain applications they may be competitive with open-web steel joists [1]. In the last decade researchers have tried to examine the web opening shapes of perforated steel sections in order to provide a better understanding of the stress distribution in the vicinity of the web openings, and to identify those that have the best structural behaviour under certain types of loading [2,3]. The aim is to provide the maximum possible web opening area for the integration of services, whilst keeping the minimum possible self weight for different types of loading.
Detailed Study of Perforated Beams with Closely Spaced Novel Web Opening
18th IABSE Congress, 19-21 September, 2012, Seoul, Korea, IABSE Press
This paper presents a detailed study of the behaviour of perforated steel beams with closely spaced web openings. Seven specimens including two typical cellular beams (i.e. circular web openings) and five perforated beams with novel web opening shapes were tested previously by the authors, to investigate the failure mode and load strength of the web-post between two adjacent web openings. These new novel web opening shapes improve the structural performance of the perforated beams with respect to web-post buckling failure. In addition, the manufacturing procedure of these novel web openings is improved and leads to sustainable design. The effects of web opening spacing/web opening depth of web-posts as well as the web opening depth/web thickness were studied to investigate the stability (slenderness) of the web-post subjected to vertical shear load. In comparison with the conventional cellular beams, significant advantages were obtained.
6th International Conference on Advances is Steel Structures, 16-18 December 2009, Hong Kong, China, pp. 213-220
The objective of this work is to investigate and compare, through an analytical study, the behaviour of perforated steel beams with different shape configurations and sizes of web openings. In this investigation the ‘Vierendeel’ failure mechanisms of steel beams with web openings are examined through a Finite Element study. The shear and flexural failures of standard perforated sections are controlled mainly by the size (i.e. depth) of the web openings, whilst the ‘Vierendeel’ mechanism is primarily controlled by the critical length of the web openings. Three main categories of web opening shape configurations and sizes are considered in this work. Standard, non-standard and elongated web opening configurations are examined, each with three different opening sizes. Four Advanced UB beams are used in the investigation in order to cover a range of sections and demonstrate the main differences in behaviour. The results of this comprehensive FE study are presented and include the position of plastic hinges, the critical opening length of perforated steel sections and the ‘Vierendeel’ parameters. The yield patterns and the failure modes do not differ dramatically. The results of this study are considered as relevant for practical applications as: (i) the reduction of the moment capacities of the tee-sections due to combination of axial and shear forces is smaller compared to the previous conservative linear interaction formula, and (ii) the formation of the initial plastic hinges at the low moment side (LMS) of the top tee-sections of the web openings does not usually cause failure, meaning that the beams can continue to carry additional load until all four plastic hinges are formed in the vicinity of the web openings and a ‘Vierendeel’ mechanism is fully established.
STUDY OF STEEL BEAM WITH WEB OPENINGS: A REVIEW
The basis of this study is the serviceability requirement which arouse long after the structural erection has been completed. Beams with web openings can be competitive in such cases, even though more alternatives to solid web beams such as stub girders, trusses etc. are available and height limitation is common problem faced by designers in multistoried buildings due to economic requirements and aesthetical considerations. Substantial spaces are normally required to enable the passage for large pipes and ducts beneath steel beams which leads to uneconomic floor heights. Though web openings could lead to a significant decrease in beam’s load carrying capacity depending on the adopted openings shape, size and location but can also be very helpful and important from the point of economy. So this study is concerned with the influence of the web opening on the strength of compressive elements and web crippling strength of steel sections. And the parametric analysis to be focused on size and location of opening. The paper summarizes the relevant study of provisions as given in the corresponding design standard and software based finite element analysis carried out by different authors and review the problem to arrive at meaningful conclusion for the study. And suggestion regarding the scope of further work.
An experimental and parametric study on steel beams with web openings
The use of steel beams with web openings (SBWOs) for structures such as industrial buildings and high-rise buildings has turned out to be extensive in recent times. There are numerous motives for which openings are kept. In this respect, an experimental investigation was planned and conducted on seven models of SBWOs. The initiative was to identify the maximum load behaviour, and deflection of steel beams with openings in the web. The performance of such beams has been considered only for vertical loads. Hot rolled steel beams of ISMB 100 with openings in the web were tested to failure. The beams were simply supported at the ends and subjected to a concentrated load applied at the mid-span. The openings considered in the experimental study are circular and rectangular only. All the beams were analysed by the finite element method by using general finite element analysis software ANSYS and the results were compared with those obtained experimentally. The test results found to be very useful for optimization of spacing-to-diameter ratio and aspect ratio of openings. The finite element results for deformation and ultimate strength shows good agreement with the corresponding values observed in the experiments. At last, a parametric study was carried out using finite element method to examine that which type of openings gives best performance during loading.
6th European Conference on Steel and Composite Structures, 31 August - 2 September 2011, Budapest, Hungary, Vol. C, pp. 1851-1856
The current method of assessment is based on FE models which still lack computational efficiency and are restricted by a number of limitations. Therefore, this work aims at the feasibility of developing FE models which are applicable to deformation and strength prediction of full scale perforated steel beams. The main area of interest is the stability of the web-post under the combined effect of shear and compression, especially at the edge of the web openings, where the stabilizing effect of tension field action is less than that at the centre of the web-post.
Steel I-shaped beams with web openings of shapes like hexagonal, circular and rectangular at regular intervals have been used since last 60-70 years. Therefore aim of this paper is to examine the behaviour of steel I-beams with rectangular web openings by performinganexperimental and parametric study. A parametric study based on finite element analysis consists of effect of fillet radius, aspect ratio of rectangular openings, stiffeners position around the openings and effect of positions of openings on load carrying capacities of steel beam with rectangular web openings was carried out by using a commercial finite element software ANSYS v.12. An overall study of such type of beam was carried out and results shows that rectangular openings having fillet radius either 2 times thickness of web or 25 mm (whichever is minimum), aspect ratio of 1.6 and reinforcement either in the form of horizontal or vertical stiffeners around the web openings found to be very effective. The fillet radius and stiffeners also affect the stress distribution around the corner regions of openings. Load carrying capacities of perforated beams are almost equal to plain-webbed beams, when openings are placed within middle two-third(neutral zone) of the span.