Title:
Evaluation of AASHTO-LRFD General Procedure for Torsion and Combined Loading
Author(s):
Khaldoun N. Rahal
Publication:
Structural Journal
Volume:
103
Issue:
5
Appears on pages(s):
683-692
Keywords:
beams; bending; reinforced concrete; shear; strength; torsion
DOI:
10.14359/16920
Date:
9/1/2006
Abstract:
The general procedure for torsion design in the AASHTO-LRFD is based on the general method, which is a simplification of the equations of the modified compression field theory. This paper presents an evaluation of this procedure by comparing the author’s results with available test data on beams subjected to various load combinations such as pure torsion, combined torsion and bending, combined torsion, bending and shear, and combined torsion and axial compression. Typical interaction diagrams between torsion, shear and bending, and axial load are also presented. The comparison shows that the method generally provides conservative results and accurate representations of the interaction between torsion and the other stress resultants. The strength of over-reinforced high-strength concrete beams (failing by crushing of the concrete before yielding of the reinforcement) can be over-estimated, however, unless the concrete strength is limited to 70 MPa (10,000 psi) in the code equation used to check crushing.