Materials and Structures

, 21:425 | Cite as

Size effect tests of torsional failure of plain and reinforced concrete beams

  • Zdeněk P. Bažant
  • Siddik Şener
  • Pere C. Prat


The current design code formulae for the torsional failure of plain or longitudinally reinforced beams exhibit no size effect, i.e. the failure of geometrically similar beams of different sizes is supposed to occur at the same nominal stress. Experiments on reduced-scale beams were carried out, and the results confirm that there is a significant size effect, such that the nominal stress at failure decreases as the beam size increases. This is found for both plain and longitudinally reinforced beams. The results are consistent with the recently proposed Bažant's size-effect law. However, the scatter of the results and the scope, and range limitations prevent it from being concluded that the applicability of this law is proven.


Concrete Beam Nominal Stress Significant Size Effect Unreinforced Specimen Nominal Shear Stress 
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  1. 1.
    ACI Standard, ‘Commentary on Building Code Requirements for Reinforced Concrete’, ACI 318M-83J (ACI, Detroit, 1984).Google Scholar
  2. 2.
    Bažant, Z. P. and Şener, S., ‘Size effect in torsional failure of concrete beams’,J. Struct. Engng. Proc. ASCE 113 (1987) 2125–2136.CrossRefGoogle Scholar
  3. 3.
    Hsu, T. T. C., ‘Torsion of structural concrete-plain concrete rectangular sections, in ‘Torsion of Structural concrete’, SP-18 (American Concrete Institute, Detroit, 1968) pp. 203–238.Google Scholar
  4. 4.
    Idem.,, ‘Torsion of Reinforced Concrete’ (Van Nostrand Reinhold, New York, 1984).Google Scholar
  5. 5.
    Humphreys, R., ‘Torsional properties of prestressed concrete’,Struct. Engnr 35 (6) (1957) 213–224.Google Scholar
  6. 6.
    McMullen, A. E. and Daniel, H. R., ‘Torsional strength of longitudinally reinforced beams containing an opening’,ACI J. 72 (8) (1975) 415–420.Google Scholar
  7. 7.
    Park, P. and Paulay, T., ‘Reinforced Concrete Structures’, (Wiley, New York, 1975).Google Scholar
  8. 8.
    Bažant, Z. P., ‘Size effect in blunt fracture: concrete, rock, metal’,J. Engng Mech., Proc. ASCE 110 (1984) 518–535.CrossRefGoogle Scholar
  9. 9.
    Idem,, ‘Mechanics of fracture, and progressive cracking in concrete structures’, in ‘Fracture Mechanics Applied to Engineering Problems,’ edited by G. C. Sih (Nijhoff, The Hague, 1985) pp. 1–94.Google Scholar

Copyright information

© RILEM 1988

Authors and Affiliations

  • Zdeněk P. Bažant
    • 1
  • Siddik Şener
    • 1
  • Pere C. Prat
    • 1
  1. 1.Center for Concrete and GeomaterialsNorthwestern UniversityEvanstonUSA

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