Longitudinal Steel Stresses in Beams Due to Shear and Torsion in AASHTO-LRFD Specifications

Accounting for the effects of shear and torsion (which cause diagonal cracks in concrete beams) on the reinforcing steel in concrete is necessary to ensure a safe design and to avoid the possibility of brittle failures. The current AASHTO-LRFD specifications and the Canadian A23.3 CSA building code use an alternative shear and torsion design method that requires a check on the adequacy of the longitudinal steel to resist the stresses not only from bending and axial loads, but also from shear and torsion. This article evaluates this general method equation for the calculation of the stresses in the longitudinal steel in members with adequate transverse reinforcement. Longitudinal steel strain readings from tests are compared with the values calculated based on the general method equation for longitudinal force. The study covers the cases of nonprestressed members subjected to combined shear and/or torsion and to prestressed and nonprestressed members subjected to combined torsion and bending. The author concludes that the AASHTO's equation provides accurate estimates of the longitudinal force in nonprestressed beams. Similar direct comparisons were not possible in partially prestressed beams, but the equation yielded conservative results in these beams. The author notes that the experimental and calculated results showed that the longitudinal steel stresses due to shear can be considerable.


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  • Accession Number: 01003914
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Sep 18 2005 11:27AM