Design and testing of steel additive-manufactured moment-resistant beam-to-column connection

The objective of this research is to study an alternative to conventional moment-resisting beam-to-column steel joints through the design of optimised connections made by additive manufacturing using steel. The proposed design is intended to fulfil design criteria such as the following: the connection has to be moment-resistant, and the different structural elements should join as easily as possible, enabling them to be attached and detached and consequently allowing the reuse of steel. The design is achieved by the application of Structural Topological Optimisation tools from the software TOSCA, and it is verified by finite element analysis using ABAQUS. The proposed design reshapes the material and leads to a uniform and optimised distribution of stresses. Blind bolts are no longer necessary and a significant weight reduction is achieved. The final design was printed with S316 stainless steel using the Selective Laser Melting technique, and it was tested under proportional loads until failure. The finite element models were validated with the experimental results. Then, the behaviour of the proposed connection under proportional and non-proportional loads is compared with that of a connection executed by traditional means (welded and bolted plates), as well as a conventional fully welded connection. The proposed connection exhibits a better behaviour than the other connections in terms of stiffness and resistance. In fact, when compared with the conventional welded connection, the values of the stiffness and strength of the optimised design are much higher. In addition, the significantly larger values of the stiffness/weight and strength/weight ratios highlight the efficiency of the proposed design.