Combined Torsion, Bending, and Shear on L-Beams

by K. S. Rajagopalan, (F.ASCE), Vice Pres.; Mullen & Powell, Inc., Consulting Engrs., Dallas, Tex.;also Adjunct Prof. of Civ. Engrg., Southern Methodist Univ., Dallas Tex.,

Serial Information: Journal of the Structural Division, 1980, Vol. 106, Issue 12, Pg. 2475-2492

Document Type: Journal Paper


Tests are reported on 15 semicontinous L-beams with stirrups under concentrated loads creating torsion combined with flexure and shear. The main variables were the amount of stirrups, torque-to-shear ratio, and the ratio of support moment to the span moment. The ultimate capacities of these beams could be predicted by the interaction proposed by Behera and ferguson. However, these tests indicate lower stresses at first diagonal cracking for beams with larger depth-to-width ratios. The postcracking torsional stiffness is only a small fraction of the precracking stiffness. Strain-gage measurements indicate that the stress induced by torsion alone (stress at a point of inflection) varies with torque in a manner similar to the variation of the twist angle. At the maximum moment section, the additional stress due to torque can be conservatively estimated as the stress at a point of inflection.

Subject Headings: Torsion | Bending (structural) | Beams | Load tests | Cracking | Stiffening | Concentrated loads | Shear tests

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