Optimisation of Novel Elliptically-Based Web Opening Shapes of Perforated Steel Beams

A new study was carried out and presented herein, on the optimisation of novel elliptically-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 classic 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

Finite Element Investigation on Web-Post Buckling of Perforated Steel Beams with Various Web Opening Shapes subjected under different shear-moment interaction

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

Experimental Study of Ultra Shallow Floor Beams (USFB) with Perforated Steel Sections

ABSTRACT: In modern building construction design, floor spans are becoming longer. Hence, steel framed structures have become more competitive when compared with traditional reinforced concrete framed buildings. In order to minimise the structural section of the composite sections, and for economic reasons, steel perforated beams are designed to act compositely with the floor slab. When the concrete slab lies within the steel flanges, as in the Ultra Shallow Floor Beam (USFB), there is an additional benefit when considering fire resistance. The aim of this study is to investigate the contribution of the concrete in composite cellular beams in the case where the concrete slab lies between the beam flanges of a steel section, when resisting vertical shear forces. The concrete between the flanges enhances the load-carrying capacity by providing a load path to transfer the shear force. Four specimens of steel-concrete composite beams with web openings in the steel section were tested in this study. One bare steel section with web openings was also tested as a comparison. This is the first such investigation of the failure mode under shear resistance (Vierendeel action) of the Ultra Shallow Floor Beam. In the test specimens, the web opening diameter is 76% of the beam depth, which is the largest currently available. This represents the worst case in terms of Vierendeel bending forces generated in the vicinity of the web openings. The smaller the hole is, the easier it is for the trapped concrete between the flanges to transfer shear across the opening. The results from the composite beam tests show a significant increase in shear resistance. The percentage of the shear capacity improvement of the particular case is presented herein as well as the failure mode of the composite beams. The shear enhancement demonstrated in this study has been utilised software that is used in design practice

FE Investigation of Perforated Sections with Standard and Non-Standard Web Opening Configurations and Sizes

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

Applications of topology optimisation in structural engineering: high-rise buildings & steel components

This study introduces applications of structural topology optimization to buildings and civil engineering structures. Topology optimization problems utilize the firmest mathematical basis, to account for improved weight-to-stiffness ratio and perceived aesthetic appeal of specific structural forms, enabling the solid isotropic material with penalization (SIMP) technique. Structural topology optimization is a technique for finding the optimum number, location and shape of “openings” within a given continuum subject to a series of loads and boundary conditions. Aerospace and automotive engineers routinely employ topology optimization and have reported significant structural performance gains as a result. Recently, designers of buildings and structures have also started investigating the use of topology optimization, for the design of efficient and aesthetically pleasing developments. This paper examines two examples of where topology optimization may be a useful design tool in civil/structural engineering in order to overcome the frontiers between civil engineers and engineers from other disciplines. The first example presents the optimized structural design of a geometrically complex high-rise structure and the optimal design of its architectural building shape. The second one focuses on the optimization and design of a perforated steel I-section beam, since such structural members are widely used nowadays in the vast majority of steel buildings and structures while they provide numerous advances. Conclusions are drawn regarding the potential benefits to the more widespread implementation of topology optimization within the civil/structural engineering industr

Derivation of dynamic properties of steel perforated Ultra Shallow Floor Beams (USFBTD) via Finite Element modal analysis and experimental verification

In recent years, the incorporation of asymmetric perforated ultra shallow floor beams (USFBs) constructed from advanced UB and UC profile beams in various composite floor systems has been extensively considered in practice. To date, limited research effort has been devoted to the detailed investigation of the dynamic properties of USFBs. In this paper, modal analyses of detailed FE models of various USFBs commonly used in composite floor systems developed in ANSYS are conducted to extract their dynamical properties (i.e. natural frequencies and mode shapes). Furthermore, experimental data pertaining to the standard impact test is also considered to validate the accuracy of the aforementioned FE results. In particular, a six meter long USFB beam is subject to impulsive excitation by means of an appropriately instrumented hammer. The dynamic properties obtained by processing the recorded response signals compare well vis-a-vis the corresponding results from the FE modal analysis. Finally, effective properties of USFBs which can be readily used in the definition of beam elements of constant cross-section along their longitudinal direction are derived. This constitutes an important step to facilitate the analysis and design of USFBs against dynamic loads at the serviceability limit state using standard commercial structural analysis software