The comparative analysis of ultimate load carrying capacity of optimally designed web-expanded steel beams

Steel I-beam sections can be modified to intensify their strength by creating a web-expanded section from a root beam. This is achieved by cutting the web of the root beam in a certain pattern with different geometries and then re-welding two parts to each other. As a result of this process the overall beam depth increases which in return causes increase in the capacity of the section. Therefore, it can be possible to cross long spans with less material. There are two common types of open web beams: beams with hexagonal openings, also called as castellated beams and beams with circular openings referred to as cellular beams. In comparison with castellated beams; there are limited theoretical and experimental research performed on cellular beams. In the literature, there is no detailed study, in which the performance and behavior of web-expanded beams with different holes which are subjected to the external loadings are carried out. The objective of the current master study is to present ultimate load carrying capacity and finite element analysis of optimally designed steel castellated beams, cellular beams and angelina beams (beams with sinusoidal web openings) under loading conditions. In the first part of the study, the design problem of web-expanded beams is formulated as optimum design problem. The minimum weight is taken as the design objective while the design constraints are implemented from AISC–ASD and BS-5950. The formulation of the design problem considering the limitations of the above mentioned turns out to be a discrete programming problem. Harmony search and particle swarm optimization methods are used for obtaining the solution of the design problem. The design algorithms based on these two techniques select the optimum IPE section to be used in the production of a web-expanded beam subjected to a general loading, the optimum geometric dimensions of different holes and the optimum number of holes in the mentioned beams. In the second part of the study, eighteen steel web-expanded beams are tested in a self-reacting frame to determine and compare the ultimate load carrying capacities of these beams. Finally, three-dimensional nonlinear finite element models of optimally designed cellular beams are also developed to validate experimental results and to perform elastic buckling analysis.