Non-linear analysis of the tubular ‘heart’ joint by FEM and experimental validation

The aim of this work is to study the behaviour of hollow circular section tubular joints which are the basic element of space frames. In order to obtain the best design, we have studied both experimentally and theoretically the different elements that constitute this joint system to determine accurately its response in the presence of the external loads. The theoretical analysis of the different variables using the finite element method (FEM) was validated by means of real tests on prototypes. The numerical analysis was carried out both on a local scale, studying the elements separately, and on a global scale, studying the ‘heart’ joint behaviour in a three-dimensional structure. The biggest difficulties in the simulation were found in the bolted joints, due to the contacts between the different elements that compose the connection and the non-linear behaviour of them. Finally, the conclusions and suggested simplified procedures of calculation to be applied in similar structures are given.