Modeling the Effects o9f Manufacturing Geometric Imperfections in the Buckling Analysis of Three-Dimensional Structure

Reticulated three-dimensional structures follow design practices based on the common assumption that joints are either rigid, or pinned. However, the actual non-linear behavior of the jointing system interaction is required to be incorporated into the analysis of the structure to accurately predict its buckling stability. Besides, currently, there is a concern on how manufacturing imperfections of these jointing systems affect the global behavior of three-dimensional structures. This dissertation incorporates and captures the effect that manufacturing geometric imperfections in the fir-tree jointing system produce in the non-linear buckling behavior of three-dimensional structures.;To understand the effect that initial manufacturing imperfections of the joints have in the buckling behavior and critical capacity of three-dimensional structures, experiments were conducted on small-scale structures to capture the actual buckling behavior of three-dimensional structures built using the GeometricaRTM 6Sd-00 fir-tree connection. Then, two finite element models identical in geometry and loading conditions to the tested structures were developed. One model was created using rigid joint connections while the other model was developed using the semi-rigid behavior of the Geometrica RTM 6Sd-00 fir-tree jointing system. These models were created to analytically: (1) asses how the rigidity of this jointing system influences the buckling behavior of three-dimensional structures and (2) predict the actual buckling behavior of three-dimensional structures built with these joints. The comparison of analytical to experimental results indicated that the finite element model that includes the semi-rigid properties of the fir-tree connections better predicted the experimentally observed buckling behavior of the tested structures than the model that uses completely rigid connections.;After the accuracy of the results obtained from the finite element model that uses the semi-rigid properties of the fir-tree jointing system were verified, finite element models of a 30-foot span three-dimensional structure were developed using this semi-rigid modeling technique under two different conditions: (1) incorporating the as-designed behavior of the jointing system and (2) using the manufactured imperfect as-built behavior of the jointing system. The semi-rigid properties of the fir-tree jointing system were obtained and utilized from a parallel research conducted at the same time as this study. The comparison of finite element simulation results of the as-designed vs. as-built three-dimensional structures modeled during this study demonstrated that manufacturing geometric imperfections in the jointing system do not have a remarkable effect on the buckling behavior and capacity of such structures.