Finite element analysis of lapped connections between cold formed steel purlins
Tutor / director / evaluatorCasafont Ribera, Miguel
Document typeBachelor thesis
Rights accessOpen Access
Cold formed steel profiles, especially the Z sections, offer a wide range of applications but one of the applications, which requires more attention and is raising some questions in the latest years, is the use of cold formed steel sections as purlins systems. The aim is to use them with maximum efficiency regarding the strength and the economic costs. Generally, this purlins systems are frequently overlapped over the interior supports to maintain their continuity in a multi-span structure. The problem that this project is approaching is the connection of the purlins over the interior supports, where these profiles have to be overlapped. Depending on the static scheme, which is chosen by the designer, the profiles have to bear a certain calculated load and the connection must ensure the continuity of the system. An important aspect of the connection is the failure mode and the plastic zones that appear, when the connection is subjected to a high load. In order to find the bearing capacity of the connection and the failure modes that appear under loading, a finite element model with shell elements using the software Ansys Mechanical, is developed. As the goal of this project is to make a parametric study on different types of profiles and to find the bearing capacity of the connections, some macros that can automatically generate the models have been created. This first part of the project aims to achieve a good, workable and practical model that can satisfy the requirements and meet the goals of this study. The boundary conditions, contact between the profiles, meshing and the parameters to choose for the analysis, all raised different problems during this process, which needed a closer look and study, in order to get a more realistic model that can behave in the end as the experimental study. In this study there are presented all the results of the analyses that have been carried out to develop the most suitable finite element model. Also, this paper contains the macros that have been generated in order to create automatically all the models needed later for the further study. The steps and the additional explanations for each of them is also included for a better understanding. All the analytical parameters are explained and studied according to their relationship with other parameters. Comparisons with similar studies and a final check with another software was also carried out to check our assumptions.