A cradle-to-site life cycle analysis of laser-cut passing-through tubular joints under different seismic conditions

Steel circular hollow sections (CHS) offer a number of advantages compared to their open section counterparts such as better resistance under tension, compression, bending in all directions and an overall reduction of structural weight, required material for corrosion and fire protection. Nevertheless, the traditional methods to connect open section beams to CHS columns often demand a significant amount of fabrication work, leading to high expenditure and resource consumption – therefore limiting their use in the current industry. These issues can be solved with an automatized joint fabrication. To that purpose, this article proposes two innovative “passing-through” I-to-CHS joints, achieved via laser cutting technology (LCT). Experimental and numerical studies were conducted to assess the joint fabrication aspects as well as the structural performance of the proposed joints. The results showed that the proposed joints can offer respectively 2.5- and 10-times larger strength and stiffness properties compared to a conventional directly welded I-to-CHS joint having similar section properties for the beam and the column. However, this study focuses on the environmental sustainability and economic feasibility of the proposed joints. A cradle-to-site life cycle analysis is conducted using multi-storey frame structures. The environmental and economic impact of the proposed joints are compared with different types of existing I-to-CHS joints in order to assess their possible benefits and limitations. Thanks to the savings in the raw material, surface treatment and transportation resources, it could be stated that, the passing-through approach with LCT offers approximately 32−42% reduction in the construction and fabrication costs of the multi-storey structures while reducing the CO2 emissions by 24−28%, compared to the directly welded I-to-CHS joints.