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Abstract

The research covered in this thesis is concerned with the effects of the behaviour and load carrying capacities of classes of steel beam structures with various shapes of web openings. A comprehensive investigation on non-composite and partially concrete encased perforated steel Isections with large web openings positioned along the centre-line of the beams was undertaken. This thesis enhances the current knowledge on these classes of perforated beams, as previous research has shown that these beams are susceptible to various failure modes, due to the existence of large web openings. Currently, perforated steel beams with large web openings are utilised in most engineering applications such as infrastructure, ship building and aeronautical engineering. The most significant benefits of using such beams are the achievement of reductions in weight and accommodation of services within their structural depth of floor systems. Specifically, in building applications, service integration eliminates the internal columns and supports, produces lighter structures which leading to reduced construction and installation time and results in cost effective structural forms and uses. However, many uncertainties are associated with perforated beams as well as non-standard methodology is used for their assessment. Perforated beams with standard circular, hexagonal and elongated web openings are most widely used nowadays, whilst various non-standard web opening shapes, such as `elliptical', are introduced through this thesis for first time. These new pioneering web opening shapes improve the structural performance of the perforated beams when examined under two critical failure modes (i. e. shear-'Vierendeel' mechanism and web-post buckling). Moreover, the manufacturing procedure of the `elliptical' web openings show great advantage in comparison with the manufacturing way of the more popular perforated beams with circular web openings (i. e. cellular beams). Also, other web opening shapes are reported and examined in this thesis. Furthermore, the novelty of the work seems to consist of the treatment of web openings of somewhat greater web opening depth than those usually considered and the introduction of a new class of composite concrete-steel beam. Despite the abundant experimental work on perforated steel beams that has been conducted by researchers throughout the years, the results are not comprehensive, due to the complexity of the beam configuration and the large number of variable parameters. Therefore, using commercially available finite element (FE) software, numerical analyses were verified by comparison to a new experimental programme designed to test each of the new structural forms. The numerical programme was then used to undertake extensive parametric studies to isolate some of the geometric and material properties that influence the failure modes associated with each of the new forms of structural systems. The main parameters under consideration are the web opening depth (noted usually as diameter), the critical opening length of the top and bottom tee-sections, the web opening spacing, the steel flange and web thicknesses, the concrete strength and contact properties between the steel and concrete of the newly formed composite beams. Detailed study of plastic hinges formation (i. e. high stress concentrations) was also employed in the vicinity of the web openings, by conducting both experimental and finite element (FE) investigation. This research study should now lead to better management of the use of perforated beams with large web openings as the profound difference between the novel and the conventional perforated beams is demonstrated. Useful practical applications of the so-called structural forms would be of particular interest in the general engineering, not just because of their superior structural performance, but also because of their low cost in manufacturing and usage. Another contribution is the investigation of the partial steel encasement with the concrete in-fill, on the percentage of enhancement of the steel perforated beams with web openings under high shear forces as well as on the distinction which is drawn between the conventional and the new composite beams. Finally, a further indirect outcome of this research thesis is the excellent agreement between the experimental and FE analyses as well as the data that can be used by future researchers to widen the above research to various engineering applications.

Publication Type:	Thesis (Doctoral)
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Departments:	Doctoral Theses School of Science & Technology > School of Science & Technology Doctoral Theses School of Science & Technology > Engineering

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