Title:
On the Probable Moment Strength of Reinforced Concrete Columns
Author(s):
Jose I. Restrepo and Mario E. Rodriguez
Publication:
Structural Journal
Volume:
110
Issue:
4
Appears on pages(s):
681-690
Keywords:
biaxial bending; capacity design; codes; confinement plastic hinges; long-term concrete strength; probable moment strength; reinforced concrete columns; seismic design
DOI:
10.14359/51685753
Date:
7/1/2013
Abstract:
The probable moment strength (or flexural overstrength, as it is also known) is the theoretical maximum flexural strength that can be calculated for the critical section of a member, with or without axial load, subjected to bending in a given direction. In ACI 318, this strength is needed to capacity-design beams, columns of special-moment frames, and columns not designated as part of the seismic-resisting system. Supported on a column database, this paper provides evidence that the current method prescribed by ACI 318 to calculate this strength has a clear nonconservative bias and explains the reasons for this. To improve predictability, the authors propose a very simple, statistically calibrated mechanics model for determining the probable moment strength of rectangular and circular columns. An extension of the concept is made for computing the probable moment strength of rectangular columns subjected to bending along the two principal axes.