Optimizing Steel Connections in Spatial Structures: Prototyping Joinery with a Focus on Wire Arc Additive Manufacturing for Structural Efficiency and Fabrication

Abstract

Structural steel joints are a critical component in design that can determine the success of any architectural project. Steel connections are fundamental to architectural design, impacting structural integrity, safety, and aesthetic quality. While typical joints at a smaller scale have been mastered in the construction industry, developing unique structures in a larger context with custom joinery often creates challenges with accuracy, efficiency, and manufacturing cost. An alternative to conventional techniques is Additive Manufacturing (3D printing), which can efficiently develop optimized and intricate structural components while adhering to time and budget constraints. In particular, additively manufactured steel nodes are the prime focus of this research, which looks into developing joint designs derived from topology optimization to answer the question of whether the structural integrity can be maintained while focusing on the aesthetic appeal of the connection design. Currently, some experimentation is underway utilizing 3D-printed steel structures on a large scale. However, this stream is still relatively undeveloped and requires further exploration for efficiency and sustainability in the construction industry. The research focuses on developing small-scale prototypes of design iterations to eliminate ambiguities, selecting the more efficient design in terms of aesthetics, structure, and fabrication ability with the available technology. For this, ten experiments were done, which included six topology optimized joints and two simplified final joints, in addition to two sectional parts. The selected joint design was further tested for its key features using the Wire Arc Additive Manufacturing (WAAM) with a six-axis robotic arm in two experiments that involved approximately twelve hours of total weld time. These tests specifically explored the impact of process parameters and the main features of the joint, including achieving curvature and examining the impact of gravity on the weld pool during the deposition process. The presented research provides critical insights into how curvature can be effectively achieved, while ensuring adequate integrity and structural performance. The findings from the presented experiments contribute to new possibilities of structural design to understand how different typologies of joints impact structural performance while not limiting design possibilities.