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Materials and Structures

, Volume 25, Issue 7, pp 423–428 | Cite as

Reliability of testing procedures for reinforced concrete structures experimentally checked on bending-stressed beams

  • B. De Nicolo
  • F. Mistretta
  • E. Pozzo
Article
  • 69 Downloads

Abstract

The investigation, carried out to check the reliability of testing procedures for reinforced concrete structures reported in Eurocode 2 (1988), has revealed situations in which bending-stressed beams, even when seriously defective, could be judged correctly built because residual deflections after the first or second short-term loading may remain within the limit set by EC2 for passing the test. Even an eventual check on elastic deformability, at least as usually carried out, does not substantially improve the reliability, which definitely improves only if the theoretical deflections are calculated with particular care (among other things, by experimentally measuring the concrete elastic modulus and by introducing the real value for the homogenization coefficient for steel areas instead of the conventional one); but, though it appears capable of revealing anomalies in the stress level in concrete, it fails to reveal a lack of concrete strength. It can be concluded that these procedures need improvement.

Keywords

Concrete Structure Concrete Strength Concrete Beam Elastic Deformability Elastic Deflection 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Resume

Les études menées pour vérifier la fiabilité des modes opératoires d’essai des structures de béton armé, décrites par l’Eurocode 2 (1988), ont mis en évidence des cas où des poutres contraintes en flexion, même lorsqu’elles étaient très défectueuses, ont pu être jugées correctes, du fait que, après le premier ou le deuxième chargement de courte durée, des courbures résiduelles peuvent subsister dans la limite admissible de l’Eurocode 2.

Même une vérification éventuelle de la déformabilité, du moins telle qu’elle est effectuée en général, n’améliore pas notablement la fiabilité, qui ne progresse nettement qui si les flèches théoriques sont calculées avec un soin particulier, notamment en mesurant expérimentalement le module élastique du béton et en introduisant la valeur réelle du coefficient d’homogénéisation pour les zones d’armature au lieu du coefficient conventionnel; cependant, si on peut ainsi détecter des anomalies dans le niveau de contrainte du béton, on ne peut déceler un défaut de résistance du béton. En conclusion, ces méthodes demandent à être améliorées.

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References

  1. 1.
    Eurocode No. 2—Second Consolidated Draft (EC2 Editorial Group, April 1988).Google Scholar
  2. 2.
    Pozzo, E., ‘A new methodology for safety evaluation in reinforced concrete structures by experimental tests’, Ist Scienza Costr., R.R.42 (1978).Google Scholar
  3. 3.
    Idem, ‘Studio di nuove metodologie di collaudo delle strutture in calcestruzzo semplice ed armato’, Giornate AICAP, Bari, May 1983.Google Scholar
  4. 4.
    Martinez y Cabrera, F. and Pozzo, E., ‘Experimental control of deformability at short-term loadings in testing large-span prestressed structures’,Mater. Struct.,25 (1992) 231–238.Google Scholar
  5. 5.
    Cruciani, G., Pinna, M. and Pozzo, E., ‘Testing procedures for prestressed structures checked for reliability on bending-stressed elements’, CESMASOC, University of Cagliari, R.R. 27 (1990).Google Scholar
  6. 6.
    ‘Norme tecniche per l’esecuzione di opere in c.a. normale, precompresso e metalliche’, Decr. Min. (1987).Google Scholar
  7. 7.
    Yu, Wein Wen and Winter, G. ‘Instantaneous and long-time deflections of reinforced concrete beams under working loads’,ACI J. Proc. 57 (2) (1960) 29–50.Google Scholar
  8. 8.
    ACI Comm. 435, ‘Variability of deflections of simply supported reinforced concrete beams’ (ACI, Detroit, reapproved 1984).Google Scholar
  9. 9.
    Branson, D. E., ‘Deformation of Concrete Structures’ (McGraw-Hill, New York, 1977).Google Scholar
  10. 10.
    Favre, R., Koprna, M. and Putallaz, J. C., ‘Deformations of concrete structures: theoretical basis for the calculation’, IABSE Periodica No. S-16/81 (Zürich, 1981).Google Scholar
  11. 11.
    Jaccoud, J. O. and Favre, R., ‘Deflection of reinforced concrete structures: experimental confirmation of a computing method’,Ann. Inst. Tech. Bât. Trav. Pub. (Paris) No. 406, (Beton 208) (1982).Google Scholar
  12. 12.
    ‘CEB manual on cracking and deformation’, Bull. No. 158-E (Comité Euro-international du Béton, Lausanne, 1985).Google Scholar
  13. 13.
    CEB-FIP Model Code (1978).Google Scholar
  14. 14.
    CP110: Part 1, ‘Code of practice for the structural use of concrete’, (British Standards Institution, 1972).Google Scholar
  15. 15.
    Consenza, C. and Greco, C., ‘Comparison and optimization of different methods of evaluation of displacements in cracked reinforced beams’Mater. Struct. 23 (1990) 196–203.CrossRefGoogle Scholar
  16. 16.
    ‘CEB design manual on structural effects of time-dependent behaviour of concrete (Georgi Saint-Sapharin, 1984).Google Scholar
  17. 17.
    Espion, B., ‘Long-term sustained loading tests on reinforced concrete beams: a selected data base’,Bull. Service Génie Civil No. 88-1 (Université Libre de Bruxelles, 1988).Google Scholar
  18. 18.
    Espion, B. and Halleux, P., ‘Long term deflections on reinforced concrete beams: reconsideration of their variability’ACI J. (March–April 1990).Google Scholar
  19. 19.
    Como, M. and Malangone, P., ‘Sulla risposta delle sezioni in c.a., ad incrementi istantanei di sforzo successivi a sollecitazioni permanenti,Giorn. Genio Civile 120 (Jan 1982) 3–24.Google Scholar

Copyright information

© RILEM 1992

Authors and Affiliations

  • B. De Nicolo
    • 1
  • F. Mistretta
    • 2
  • E. Pozzo
    • 1
  1. 1.Department of Structural EngineeringUniversity of CagliariCagliariItaly
  2. 2.University of CagliariCagliariItaly

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