The University of Navarra (UNAV) is a non-profit private university founded in 1952 based in Pamplona, Spain. It confers 56 official degrees and administers more than 90 postgraduate programs (including 20 doctoral programs and 42 master’s programs) through 10 schools, two superior colleges, the IESE Business School and its 5 comprehensive Research Centres: CCUN (Cancer Centre Clínica Universidad de Navarra), BIOMA (Biodiversity and Environment Institute) and DATAI (Institute of Data Science and Artificial Intelligence), ICS (INSTITUTE FOR CULTURE AND SOCIETY and CIN (Centre for Nutrition Research).

UNAV has more than 14.000 students in 5 campuses: Pamplona, San Sebastian, Madrid, Barcelona and New York with a wide network of international universities and research centres.

UNAV has a sound track record in participating in European Research Programs. The university has participated in 126 European projects from FP4 to Horizon Europe, including LIFE, ERASMUS+ and INTERREG Programs; of which 22 projects were coordinated by the university. The University also counts with a thorough experience in MSCA and ERC grants with over 26 signed grants.

UNAV been awarded with the HR Excellence in Research quality seal (HRS4R) that guarantees the implementation of the European Charter for Researchers and the Code of Conduct for the Recruitment of Researchers.

Hosting Research Group and Background

The research team has been researching 2D and 3D semi-rigid steel joints for more than 2 decades. In the beginning, the research line was based on the components method proposed by Eurocode 3. This regulation assumes that real joints behave in an intermediate way between pinned joints (zero stiffness and moment) and rigid ones (infinite stiffness and total moment). In other words, the structural elements, beams and columns, are really connected by joints of finite stiffness and strength. These joints transmit part or all of the bending moment and have a rotation capacity that contributes to the redistribution of forces throughout the structure. Therefore, the stiffness and strength of the joint must be characterized in an iterative way with the global analysis of the structure. This characterization is based on the decomposition of the joint into components, each of which is in turn characterized as a spring, with an axial stiffness and strength that is assembled to obtain rotational stiffness and strength.

This method lacks the desired reliability as it incorporates interaction parameters that lead to certain inaccuracies in the calculation. That is why the research group has been proposing the implementation of alternative calculation approaches, such as the 12 degrees of freedom cruciform element. This model eliminates the interaction parameter and, at the same time, it is much easier to implement than a mechanical model by components. Initially, this model was developed considering the stiffnesses provided by the components method. In the last projects the element was built by means of a direct substructure method from a finite element model thus avoiding the simplifications and weak points of the component model. The more complex the joints, the more necessary these alternatives are, that is, in  3D joints, or joints under out-of-plane loads, for example. However, these alternative methods also become very complex by having to consider all the interactions that occur between the different degrees of freedom of the joint.

On the other hand, when it comes to designing a steel structure, the structural designer finds the added difficulty that many of the joints frequently used in daily practice are not defined in the current regulations, and there are no tools available for their correct characterisation.

In the last project, the research group has been exploring the design of moment-transmitting beam-column connections taking advantage of new additive manufacturing technologies and applying optimisation techniques. Instead of searching for ways to characterize complex connections in order to design the steel structures in which they are involved reliably, it is sought to design the beam-column connection that responds to complex situations, responding with the characteristics required, without the geometric limitations imposed by traditional manufacturing techniques based on welded profiles and plates. Metal Additive manufacturing, combined with structural topological optimization, can allow to create the joint element with the characteristics we need for a given structure, in terms of geometry, stiffness and strength. Hence, this combination may represent an advance in the industrialization of construction, the execution of singular elements that are complex to carry out by means of traditional methods, efficiency in the use of the material, as well as enabling the possibility of assembly and disassembly, favoring the reuse of structural elements, with the consequent contribution to sustainability.

Highlighted Publications

1. Proposal and experimental verification of additive manufactured beam‐column connection designed by topological optimization, 2023, B Gil, R Goñi, M Fábregas, E Bayo, ce/papers 6 (3-4), 702-707
2. Preliminary study of axial‐moment interaction diagrams for semi‐rigid end plate bolted connections, 2023, J Gracia, B Gil, E Bayo, ce/papers 6 (3-4), 1381-1386
3. Axial-moment interaction for 2D extended end plate bolted steel connections. Experimental investigation and assessment of the initial imperfections, 2022, B Gil, J Gracia, E Bayo, Journal of Building Engineering 60, 105134
4. Major axis steel joint with additional plates subjected to torsion: Stiffness characterization, 2020, B Gil, R Goñi, E Bayo, Engineering Structures 220, 111021
5. Major axis steel joint under torsion: Stiffness and strength characterization, 2019, B Gil, R Goñi, F Bijlaard, E Bayo, Engineering Structures 180, 586-602       
6. Initial stiffness and strength characterization of minor axis T-stub under out-of-plane bending, 2018, B Gil, R Goñi, E Bayo, Journal of Constructional Steel Research 140, 208-221      
7. Progress in the Characterization of Three-Dimensional Semi-Rigid Steel Connections, 2016, E Bayo, B Gil, R Goñi, J Gracia, Connections VIII 8, 373-382
8. T-stub behaviour under out-of-plane bending. I: Experimental research and finite element modelling, 2015, B Gil, R Goñi, Engineering Structures 98, 230-240
9. T-stub behavior under out-of-plane bending. II: Parametric study and analytical characterization, 2015, B Gil, F Bijlaard, E Bayo, Engineering Structures 98, 241-250
10. Experimental and numerical validation of a new design for three-dimensional semi-rigid composite joints, 2013, B Gil, R Goñi, E Bayo, Engineering Structures 48, 55-69      
11. An efficient cruciform element to model semirigid composite connections for frame analysis, 2012, E Bayo, J Gracia, B Gil, R Goñi, Journal of Constructional Steel Research 72, 97-104 
12. An alternative design for internal and external semi-rigid composite joints. Part I: Experimental research, 2008, B Gil, E Bayo, Engineering Structures 30 (1), 218-231
13. An alternative design for internal and external semi-rigid composite joints. Part II: Finite element modelling and analytical study, 2008, B Gil, E Bayo, Engineering Structures 30 (1), 232-246           
14. Practical and efficient approaches for semi-rigid design of composite frames, 2007, B Gil, E Bayo, Steel and Composite Structures 7 (2), 161-184                   
15. An effective component-based method to model semi-rigid connections for the global analysis of steel and composite structures, 2006, E Bayo, JM Cabrero, B Gil, Engineering structures 28 (1), 97-108          

Laboratory equipment

• Double loading structure for tests type PEV-2/400-W from Ibertest with servohydraulic system and computerized control with capacity of 400 kN per gantry.
• Vishay 7100 data adquisition system with 8 channels capacity with StrainSmart Data Acquisition System Software for readings of inclinometers, load cells, displacement sensors, strain gauges, etc. And Vishay 5000 data acquisition system with 64-channel capacity.
• Four 200 kN capacity Tedea-Huntleigh model 220 load measuring cells.
• Five Hoskin ES 261-OP inclinometers for the measurement of turning angles.
• Six Unimeasure LX-PA wire sensors with ranges between 10 and 20 cm for measurement of displacements.
• A Waycon laser sensor model LAS-T5-500-10V with a range of 500 mm. for measuring displacements.
• 5 LVDT Schreiber SM260.100.2ST for displacement measurement.
• 1 LVDT Schreiber SM260.40.2ST for displacement measurement.
• Electromechanical press tracc-comp 20/5 t Ibertest STIB 200 with capacity for loads of 200 kN.
• Workstations.
• ABAQUS® (Simulia Research Suite) finite element analysis software.
• BQ Witbox 3D printer and Sidewinder Artillery printer, for printing with PLA filament, UPbox 3D Printer, for printing with ABS; Prusa i3 3D printer, for printing with filament, multimaterial. 3D FormLab Form 3 printer, for printing with resins. 3D printer, Mark Forged, Mark 2, for carbon fiber printing.

REQUIREMENTS OF THE CANDIDATE