Stiffness assessment of bases of off-centre loaded steel columns according to EN 1993-1-8

Introduction. The practice of metal structure design shows that the actual performance of nodal joint structures is almost never a “pure” hinge, and there is no “absolutely rigid” connection of elements. In EN 1993-1-8, metal structure assemblies are classified as rigid, nominally hinged and semi-rigid depending on the ratio of the initial rotational stiffness of the assembly to the reduced linear stiffness. The relevance of this study lies in the clarification of the criteria for classifying the bases of off-centre compressed columns as rigid, which will allow the EN 1993-1-8 methodology to be used in domestic design practice.

Materials and methods. The study uses comparative analysis of typical solutions for the bases of off-centre compressed columns and assesses their stiffness according to EN 1993-1-8. An analysis of the influence of the pliability of the bases of off-centre compressed columns of single-storey industrial buildings with a sway frames on the design length of the column and the yield strength reduction factor has been performed.

Results. Classification of steel structure assemblies from the point of view of structural performance is given, in accordance with the domestic practice of steel structure design based on SNiP II-23 (СP 16.13330). Differences in the classification of assemblies depending on their rotational stiffness according to EN 1993-1-8 are presented. The stiffness of bases of typical columns is evaluated and recommendations for changing the criterion of their classification are developed.

Conclusions. The stiffness of typical off-centre loaded column bases was assessed. It was found that more than 50 per cent of typical column bases are semi-rigid, which is unacceptable according to EN 1993-1-8. The stiffness of the column bases is less affected by the thickness of the slab and the strength class of the foundation concrete. The stiffness is 60 % dependent on the steel grade and diameter of the anchor bolts and the height of the column. Based on this, it is recommended to revise the design solutions adopted in the standard solutions or the criteria for classifying the column base type as rigid.

1. Shuryn A.B., Tusnin A.R., Zinkevich I.V., Muk­hin A.V. Design of steel structures in accordance with EUROCODES requirements : tutorial. Moscow, ASV, 2021; 222. (rus.).

2. Shuryn A.B., Nadolski V.V. Experience of implementation of Eurocodes in the design of steel structures in the Republic of Belarus. Vestnik MGSU [Monthly Journal on Construction and Architecture]. 2024; 19(5):740-751. DOI: 10.22227/1997-0935.2024.5.740-751. EDN JAVYTK. (rus.).

3. Shuryn A.B., Mukhin A.V. Experience in designing trusses from bent-welded profiles in accordance with the requirements of EN 1993-1. Everyday structures from metal and wood : collection of scientific works. 2020; 24:141-149. (rus.).

4. Tusnina V.M. Semi-rigid steel beam-to-column connections. Magazine of Civil Engineering. 2017; 5(73):25-39. DOI: 10.18720/MCE.73.3. EDN ZNLKNH.

5. Ferdous W. Effect of beam-column joint stiffness on the design of beams. 23rd Australian Conference on the Mechanics of Structures and Materials. 2014; 701-706.

6. Bandyopadhyay M., Banik A. Numerical analysis of semi-rigid jointed steel frame using rotational springs. International Conference on Structural Engineering and Mechanics (ICSEM). 2013.

7. Tusnina V.M., Platonova V.D. Numerical analysis of the stiffness of the “beam-column” flange joints. Industrial and Civil Engineering. 2020; 9:28-33. DOI: 10.33622/0869-7019.2020.09.28-33. EDN ELLLJF. (rus.).

8. Wald F., Gresnigt A.M., Weynand K., Jaspart J.P. Application of the Component Method to Column Bases. COST C1 Conference Liege 1998. 1999; 155-166.

9. Column Bases in Steel Building Frames / ed. K. Weynand. Brussels, 1999.

10. Wald F., Seifert J. The Column-Bases Stiffness Classification. Nordic Steel Colloquium. 1991; 309-316.

11. Bijlaard F., Steenhuis M. Prediction of the influence of connection behaviour on the strength, deformations and stability of frames, by classification of connections. Proceedings of the Second International Workshop on Connections in Steel Structures. 1992; 307-318.

12. Jaspart J.P., Wald F.A.E., Weynand K., Gres­nigt N. Steel column base classification. HERON. 2008; 53(1/2):69-86.

13. Ghosh U.K. Design of welded steel structures: principles and practice. Taylor & Francis, 2016; 244.

14. Degertekin S.O., Hayalioglu M.S. Design of non-linear semi-rigid steel frames with semi-rigid column bases. Electronic Journal of Structural Engineering. 2004; 4:1-16. DOI: 10.56748/ejse.437

15. Alpatov V.Yu., Lukin A.O., Saharov A.A. The study of rigidity of a steel column base assembly consisting of a support plate. Industrial and Civil Engineering. 2015; 9:9-14. EDN UKFKDV. (rus.).

16. Fisher J.M., Kloiber L.A. Steel Design Guide 1. Base Plate and Anchor Rod Design. 2nd Edition. AISC, 2006; 62.

17. Wald F., Sokol Z. Column Base Stiffness Classification. Stability and Ductility of Steel Structures. 1997; 675-682.