Investigation of the behaviour of reinforced elliptical hollow section welded joints exposed to axial load

In the recent years, application of the structures made of Elliptical Hollow Section (EHS) has become popular among tubular sections due to their aesthetic appearance and engineering advantages. The important feature of EHSs in terms of architectural point of view is that it is possible to have slender appreance since they have two different diameters. The other advantage of the EHS members is that surface wind load effect is reduced because of that there is no sharp corners as Square or Rectangular Hollow Sections. It is possible to form welded EHS T-joints with four different type orientations. They are called as Type-1, Type-2, Type-3 and Type-4. Brace members are welded to the wide side of the chord member in Type-1 and Type-2, while the brace members are connected to the narrow side of the chord member in Type-3 and Type-4. Therefore, the axial load carrying capacity of the Type-1 and Type-2 is smaller than that of Type-3 and Type-4. Plastification of the chord face generally governs to capacity of the EHS joints. As a result, the axial load carrying capacity of the tubular joints may be improved by using a reinforcing plate around the brace-to-chord intersection region. This study focuses on the axial load carrying capacity of axially loaded reinforced EHS T-joints Type-1 and Type-2 since the chord member works on its weak axis. Currently, there is no design method to calculate the axial load carrying capacity of the reinforced EHS T-joints. This study examines the failure modes and the resistance of reinforced EHS T-joints subjected to axial compressive load using finite element method. Before the parametric studies, the results of the numerical models created using non-linear finite element solfware, ABAQUS v6-14.1 were validated against the available test data. According to this validation study, parameters such as finite element type, metarial type, mesh size and time step, which are considered in non-linear numerical analyses for parametric studies, were determined. After the validation study, a series of parametric studies were carried out on the axially loaded EHS T-joints, considering a wide range of geometric parameters. The numerical results show that the effects of the reinforcement plate on the axial load carrying capacity of reinforced EHS T-Joints based on multiple linear regression analyses. In this thesis, a safe and economical calculation method for calculating axial load carring capacities of reinforced EHS T-Joints was introduced and this method was validated by comparing with numerical results.