Torsional behavior of spandrel beams
Mogbo, Nathan Chidozie
Jirsa, James O.
Master of Science
This investigation concerns the problem of load transfer from the slab through the spandrel beams (edge beams) to the exterior columns in flat plate construction. The load is transferred from the slab to the spandrel beam through a combination of shear and bending forces. The spandrel beam in turn transfers the load to the exterior column primarily by torsion. Hence the strength of the slab is controlled by the strength of its supporting members. The behavior and strength of the spandrel beams of nine 0.3 scale reinforced concrete flat plate specimens are described in this report. The influence of shear and bending moments on the torsional capacity of the beams is discussed and equations for predicting strength examined. The primary variables in the tests were the beam dimensions and reinforcements The results showed that the initial torsional stiffness of the spandrel beams was dependent on the size and shape of the spandrel beams while the post-cracking stiffness was a function of the beam torsional reinforcement. For design purposes, spandrel beams can be treated as isolated beams provided that the bending and shear forces on the beam are not significants Comparisons were made between the computed and measured torsional capacities of the spandrel beams and these comparisons showed that the extension developed by Hsu (3) are satisfactory for, predicting the torsional strength of spandrel beams.