Title: Torsional Limit Design of Spandrel Beams
Author(s): Thomas T. C. Hsu and Ching-Sheng Hwang
Publication: Journal Proceedings
Appears on pages(s): 71-79
Keywords: angle of twist;beams (supports);bending;columns (supports);cracking (fracturing);hinges (structural);limit design method;reinforced concrete;shear properties;shear stress;spandrel beams;structural design;torsion;torsion tests; ultimate strength method.
Based on moment redistribution, limit design criteria for spandrel beam subjected to torsion in addition to shear and bending have been developed by ACI Committee 438, Torsion, and are being considered by ACI Committee 318 for the incorporation into the ACI Building Code. These criteria require a critical section to resist a specified torsional cracking stress of so as to insoure the formation of a torsional plastic hinge. This paper reviews this proposed esign criteria particularly in its application to the critical sections in a continous spandrel beam near the column faces where both torques and shears are large. An alternate method to provide a minimum amount of torsional web reinforcement is also given. The application of the new torsional design provisions are illustrated by an example problem in a separate appendix.