Stability of Tapered Cantilever Beam Under Torsion

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Title: Stability of Tapered Cantilever Beam Under Torsion

Author(s): T. AmirsoleymaniI

Publication: Special Publication

Volume: 128

Issue:

Appears on pages(s): 1033-1048

Keywords: bending moments; cantilever beams; cracking (fracturing); finite element method; loads (forces); reinforcing steels; repairs; shear properties; stability; stadiums; structural analysis; torsion; structural design; Structural Research

Date: 11/1/1991

Abstract:
The largest sports stadium of Iran consisting of 36 concrete cells was completed in 1974. As extensive cracks formed in the beams and walls, the repair work on concrete and post-tensioning of the beams were undertaken. After a few years, propagation of cracks was observed in most of the tapered cantilever beams. The re-evaluation of structural analysis and material tests showed that formation of horizontal cracks could be attributed to discontinuities in the materials such as dowels or sharp intrusion at the surface. In all of the tapered cantilever beams, the longitudinal reinforced bars were one-half to one-third of the required amount given in ACI 318-83. The actual load had been more than initial design load on numerous occasions throughout the last 15 years without resulting in total failure. Therefore, it is recommended to re-evaluate the minimum requirement for longitudinal reinforcement bars and to consider the use of balanced torsional stiffness for tapered cantilever beams under intensive torsion.