Automated off-site fabrication of steel structures
Steel joint fabrication using laser cutting
We aim to improve both the fabrication process and structural characteristics of tubular joints. In the recently concluded EU-RFCS LASTEICON project we achieved this by Laser Cutting Technology (LCT).
In the project, we tested 36 two-way steel joints under monotonic gravity, opposite bending and shear loading conditions. The new joint configurations performed better than the conventional tubular joint options with up to 2.5x more resistance and 10x more stiffness. The superior structural performance translated in significant economic and environmental benefits (up to 35% saving in steel frame costs).
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Our latest article on the subject: Couchaux M., Vyhlas V., Kanyilmaz A., Hjiaj M., Passing-through I-beam-to-CHS column joints made by laser cutting technology: Experimental tests and design model, Journal of Constructional Steel Research, Volume 176, 2021, 106298, ISSN 0143-974X, https://doi.org/10.1016/j.jcsr.2020.106298.
Bio-inspired topology optimization and additive manufacturing
Nature’s structures are often tubular. Their joints (e.g. the knees of a human body, the nodes of trees and plants) are intrinsically optimized to maximize stiffness, resistance, and robustness. The 3D metal printing technology can enable a custom optimization of steel tubular joints, saving material waste and decreasing fabrication costs, since it is free from the constraints of traditional manufacturing.
In cooperation with multiple players (architects, manufacturers, producers), we have been studying new tubular joint shapes using solid isotropic material with the penalization method (SIMP) to maximize the structural performance and minimize fabrication complexity to reduce costs, increase customization and cut waste as well as the carbon footprint of the sector.
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Here we presented a ‘hybrid’ manufacturing approach by welding optimized printed nodes to conventional steel elements, and our numerical modeling approach for its structural integrity study:
Conceptual design using machine learning
More on this will be published soon.
Mitigation of dynamic actions (seismic, fatigue) on structures
Earthquake-resistant structures using repairable connections with increased lifetime and sustainability
We have been developing and testing seismic resistant composite steel frames with dissipative fuses, where the earthquake damage can concentrate during the seismic event, after which the repair work will be limited only to replacing the fuses. Currently, our team in Politecnico di Milano is coordinating the research project DISSIPABLE “Fully Dissipative and Easily Repairable Devices for Resilient Buildings with Composite Steel-Concrete Structures”, funded by EU-RFCS with contract n. RFCS-PDP 800699, 2018-2021. DISSIPABLE team is performing large scale demonstration of the steel-concrete composite structures with anti-seismic reparable systems. In the project, systematic post-earthquake repair and reassembly procedures are being developed and will be provided as “instructions for use” in the end. We are quantifying the economic and environmental benefits of the tested systems.
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Advanced structural solutions for automated steel rack supported warehouses
Automated Rack Supported Warehouses (ARSW) represents the future of storage technology, providing substantial savings in terms of cost, space and energy with respect to traditional warehouses. Currently, designers refer to building codes, without controlling their applicability to the specific typologies of such structures. This creates safety and efficiency problems being ARSWs’ structural characteristics considerably different from those of steel structures for normal buildings. Objective of the research is to analyse actual design practices, to investigate logistics’ imposed loading strategies, unconventional loading conditions, constructional phases and seismic design and to propose new approaches aiming at increasing ARSW safety, reliability and economy.
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Seismic design of concentrically braced frames under low-to-moderate seismicity
Within MEAKADO research project, we proposed an adjusted design approach for the low-to-moderate seismicity design of Concentrically Braced Frame (CBF) structures. With the new approach, we aim to satisfy both economy and safety criteria, based on the exploitation of the three features of CBFs, which had not been deeply examined before: “frame action provided by gusset plates”, “contribution of compression diagonal and its post-buckling strength and stiffness”, and “energy dissipation capacity of non-ductile bracing joint connections”.
We investigated these aspects by means of incremental dynamic analysis of case studies, based on the numerical models calibrated on full-scale experimental tests published elsewhere by us.
Based on the results of full-scale experiments, we quantified the ductility provided by the bolt hole ovalization and the slippage of preloaded bolts of standard bracing joints of concentrically braced frames that are not fulfilling the current over-strength design criteria.
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