Nonlinear mechanics and design of prestressed stayed columns

Research Team

• Professor Ahmer Wadee: Imperial College London
• Professor Leroy Gardner: Imperial College London
• Dr Daisuke Saito: Mott McDonald (former PhD student)
• Dr Adelaja Osofero: Atkins Hong Kong (former RA)
• Professor Roger Hobbs: Imperial College London
• Mr Jialiang Yu: Imperial College London

Background

Prestressed stayed columns are cable stiffened struts that are used in practice to increase the buckling resistance. They are often used in practice in shoring applications where the deployment of trestle structures would be uneconomical. However, because of their optimized nature the behaviour of such structures is likely to be less than obvious - increasing the prestress within the stays only increasing the stability in some cases. The work conducted by Professor Wadee and his former research student Daisuke Saito has quantified this into zones [1,8] directly connected with the level of prestress applied to the cables where the post-buckling behaviour is strongly stable and, more dangerously, strongly unstable. In fact, the most unstable case seems to be the one which the previous literature had identified to be the best design configuration [1,4].

Work has continued to examine the effects of imperfections and inelasticity in the response [2], modal interactions [3,5,9-12], experimental validation [5,6] and the development of design guidance [7].

Methodology

The analytical work employs energy methods such as Rayleigh-Ritz in conjunction with the symbolic computation package Maple to develop mathematical models that account for the nonlinear buckling response of the prestressed stayed strut. The models are validated using full-scale physical experiments in Imperial's Structures Laboratory and the extensive use of the commercial finite element code ABAQUS.

Seminars and Conference Presentations

• July 2015
  Lisbon, Portugal. 8th International Conference on Advances in Steel Structures (ICASS 2015).
• June 2015
  Stanford University, California. ASCE Engineering Mechanics Institute Conference (EMI 2015). Talk delivered by Jialiang Yu.
• September 2012
  London, UK. 14th International Symposium of Tubular Structures (ISTS-14).
• July 2012
  London, UK. Arup Research Seminar.
• July 2011
  Rome, Italy. 7th European Nonlinear Dynamics conference (ENOC 2011).
• September 2010
  Cape Town, South Africa. Fourth International Conference on Structural Engineering,
  Mechanics and Computation (SEMC 2010).
• August 2010
  Pretoria, South Africa. Joint Structural Division of the South African Institution of Civil Engineers. Research Seminar.
  
• July 2010
  1) Johannesburg, South Africa. Joint Structural Division of the South African Institution of Civil Engineers. Research Seminar.
  2) School of Civil and Environmental Engineering, University of the Witwatersrand, Johannesburg, South Africa. Research Seminar.
• July 2009
  Leeds, UK. Ninth International Conference on Steel Concrete Composite and Hybrid Structures (ASCCS 2009).
• January 2008
  University of Bath, Centre for Nonlinear Mechanics. Brooke Session (Delivered by Daisuke Saito).
• September 2007
  Cape Town, South Africa. Third International Conference on Structural Engineering,
  Mechanics and Computation (SEMC 2007).
  

References

1. Saito, D. and Wadee, M. A., 2008. Post-buckling behaviour of prestressed steel stayed columns. Eng. Struct. 30:1224-1239.
2. Saito, D. and Wadee, M. A., 2009. Buckling behaviour of prestressed steel stayed columns with imperfections and stress limitation. Eng. Struct. 31:1-15.
3. Saito, D. and Wadee, M. A., 2009. Numerical studies of interactive buckling behaviour in prestressed steel stayed columns. Eng. Struct. 31:432-443.
4. Saito, D. and Wadee, M. A., 2010. Optimal prestressing and configuration of stayed columns. Proc ICE -Struct. Build. 163:343-355.
5. Osofero, A. I., Wadee, M. A. and Gardner, L., 2012. Experimental study of critical and post-buckling behaviour of prestressed steel stayed columns. J. Constr. Steel Res. 79:226-241.
6. Osofero, A. I., Wadee, M. A. and Gardner, L., 2013. Numerical studies on the buckling resistance of prestressed stayed columns. Adv. Struct. Eng. 16:487-498.
7. Wadee, M. A., Gardner, L. and Osofero, A. I., 2013. Design of prestressed stayed columns. J. Constr. Steel Res. 80:287-298.
   
8. Wadee, M. A. and Saito, D., 2007. Zones of nonlinear buckling responses in prestressed stayed columns. In A. Zingoni, editor, Recent developments in structural engineering, mechanics and computation, Rotterdam, Millpress, Pages: 291-292.
9. Wadee, M. A. and Saito, D., 2009. Interactive buckling in prestressed stayed columns. In: D. Lam, editor, Steel concrete composite and hybrid structures, Singapore, Research Publishing Services, Pages:690-696.
10. Wadee, M. A., Gardner, L. and Hunt, T. A., 2011. Mode jumping in prestressed stayed columns: A spring and link model approach. ENOC 2011: 7th European Nonlinear Dynamics Conference, Rome, Italy, European Mechanics Society.
11. Wadee, M. A., Hunt, T. A. and Gardner, L., 2012. Analytical modelling of mode jumping in the buckling of prestressed stayed columns. In: L. Gardner, editor,Tubular structures XIV: Proceedings of the 14th international symposium on tubular structures. Pages 663-670.
12. Wadee, M. A., Gardner, L. and Hunt, T. A., 2013. Buckling mode interaction in prestressed stayed colunns. Proc. ICE - Struct. Build. 166(SB8):403-412. Special issue.

Doctoral Theses

• Daisuke Saito. Post-buckling behaviour of prestressed steel stayed columns, PhD thesis, University of London, 2008. Winner of the Unwin Postgraduate Prize.
• Adelaja I Osofero. Behaviour and design of prestressed stayed columns, PhD thesis, Imperial College London, 2012.

Winner of 2nd prize in GSEPS Poster Competition 2007
Daisuke won one of the major prizes in the poster competition run by the Graduate School of Engineering and Physical Sciences (GSEPS) for research students in July 2007. His poster (PDF: 5.6 Mb) is downloadable.