Computers and Concrete

Techno-Press (테크노프레스)
권호 표지
DOI QR코드

DOI QR Code

A partial factors methodology for structural safety assessment in non-linear analysis

  • Castro, Paula M.R.P. (Faculty of Architecture, Porto University) ;
  • Delgado, Raimundo M. (Faculty of Engineering, Porto University) ;
  • Cesar de Sa, Jose M.A. (Faculty of Engineering, Porto University)
  • Received : 2004.07.01
  • Accepted : 2005.01.15
  • Published : 2005.02.25
⟨ Previous Next ⟩

Abstract

In the present structural codes the safety verification is based on a linear analysis of the structure and the satisfaction of ultimate and serviceability limit states, using a semi-probabilistic security format through the consideration of partial safety factors, which affect the action values and the characteristic values of the material properties. In this context, if a non-linear structural analysis is wanted a difficulty arises, because the global safety coefficient, which could be obtained in a straightforward way from the non-linear analysis, is not directly relatable to the different safety coefficient values usually used for the different materials, as is the case for reinforced concrete structures. The work here presented aims to overcome this difficulty by proposing a methodology that generalises the format of safety verification based on partial safety factors, well established in structural codes within the scope of linear analysis, for cases where non-linear analysis is needed. The methodology preserves the principal assumptions made in the codes as well as a reasonable simplicity in its use, including a realistic definition of the material properties and the structural behaviour, and it is based on the evaluation of a global safety coefficient. Some examples are presented aiming to clarify and synthesise all the options that were taken in the application of the proposed methodology, namely how to transpose the force distributions obtained with a non-linear analysis into design force distributions. One of the most important features of the proposed methodology, the ability for comparing the simplified procedures for second order effects evaluation prescribed in the structural codes, is also presented in a simple and systematic way. The potential of the methodology for the development and assessment of alternative and more accurate procedures to those already established in codes of practice, where non-linear effects must be considered, is also indicated.

Keywords

References

  1. EC2, Eurocode 2 (2002), "Design of concrete structures- Part I: General rules and rules for buildings", European Committee for Standardization, Ref. No. prEN 1992-1-1.
  2. MC90 - Comite Euro-International du Beton. (1990), CEB-Fip Model Code 1990, Bulletin dInformation, 204.
  3. Ferry-Borges, J. Castanheta, M. (1962), Structural safety. Laboratorio Nacional de Engenharia Civil, Lisboa.
  4. Ayyub, B. M., White G. J. (1987), "Reliability conditioned partial safety factors", J. Struct. Div., ASCE, 113(2), 279-294. https://doi.org/10.1061/(ASCE)0733-9445(1987)113:2(279)
  5. Pinto, A. (1997), "Earthquake performance of structures", Ph. D Thesis, Instituto Superior Tecnico, Lisboa.
  6. Veneziano, D. (1976), "Basic principles and methods of structural safety", Comite Euro-International du Beton, CEB, Bulletin dInformation 112.
  7. Eibl, J. (1991), "Safety considerations for nonlinear analysis", Proc. IABSE Colloquium Struct. Conc. Stuttgart, 337-348.
  8. CEB-FIP Comite Euro-International du Beton. (1988), "General principles on reliability for structures", Bulletin dInformation, 191.
  9. Liu, P. L., Kiureghian A. D. (1989), "Finite element reliability methods for geometrically nonlinear stochastic structure", Report UCB/SEMM-89/05, Department of Civil Engineering, Division of Structural Mechanics, University of California, Berkeley.
  10. Teigen, J. G., Frangopol, D. M. (1991a), "Sture S. Probabilistic FEM for nonlinear concrete structures - I Theory", J. Struct. Div., ASCE, 117(9), 2674-2689. https://doi.org/10.1061/(ASCE)0733-9445(1991)117:9(2674)
  11. Teigen, J. G., Frangopol, D. M. (1991b), "Sture S. Probabilistic FEM for nonlinear concrete structures - II Applications", J. Struct. Div., ASCE, 117(9), 2690-2707. https://doi.org/10.1061/(ASCE)0733-9445(1991)117:9(2690)
  12. Rajashekhar, M. R., Ellingwood, B. R. (1995), "Reliability of reinforced-concrete cylindrical shells", J. Struct. Div., ASCE, 121(2), 336-347. https://doi.org/10.1061/(ASCE)0733-9445(1995)121:2(336)
  13. Eibl, J, Schmidt-Hurtienne, B. (1995), "General outline of a new safety format, new developments in non-linear analysis methods", Comite Euro-International du Beton, CEB, Bulletin dInformation, 229, 33-48.
  14. Zhang, J, Ellingwood, B. (1996), "SFEM for reliability with material nonlinearities", J. Struct. Div., ASCE, 122(6), 701-70. https://doi.org/10.1061/(ASCE)0733-9445(1996)122:6(701)
  15. Macchi, G. "Nonlinear analysis. the CEB approach, new developments in non-linear analysis methods", Comite Euro-International du Beton, CEB. 1995, Bulletin dInformation, 229, 7-11.
  16. Levi, F., Marro, P., Viara, G. "Nonlinear analysis of beams and frames, new developments in non-linear analysis methods", Comite Euro-International du Beton, CEB 1995, Bulletin dInformation 227.
  17. Konig, G., Fischer, J. (1995), "Model uncertainties of design equations for the shear capacity of concrete members without shear reinforcement", Model Uncertainties. Comite Euro-International du Beton, CEB, Bulletin dInformation, 224, 49-100.
  18. Konig, G., Nguyem, T., Ahner, C. (1997), "Consistent safety format", Comite Euro-International du Beton, CEB, Bulletin dInformation, 239, 1-16.
  19. Castro, PMRP. (1998), "Models for buckling analysis of reinforced concrete framed structures", Ph. D Thesis (in portuguese), Faculdade de Engenharia da Universidade do Porto, Portugal.
  20. REBAP - Regulamento de Estruturas de Betao Armado e Pre-esforcado (1983), Decreto-lei 349-C/83, Imprensa Nacional Casa da Moeda, Lisboa, Portugal.