Title:
Stiffness Modifiers to Support Seismic Design of Reinforced Concrete Circular Columns
Author(s):
Mario E. Rodriguez and Jose I. Restrepo
Publication:
Structural Journal
Volume:
122
Issue:
5
Appears on pages(s):
139-152
Keywords:
circular columns; effective lateral stiffness; reinforced concrete; seismic analysis; stiffness modifiers; test
DOI:
10.14359/51746758
Date:
9/1/2025
Abstract:
Linear structural analysis is the method of choice commonly used by practicing engineers to support the seismic design of a structure. The structural models are developed in commercial software and incorporate stiffness modifiers, which lower the stiffness of the members, in recognition of all the sources of flexibility that occur upon cracking of the concrete. This paper describes a mechanics-based model to compute the stiffness modifiers for columns with a circular cross section. The mechanics-based model accounts for five modes of deformation observed. Calibration of this model was performed with a database of tests reported in the literature on 22 circular-section columns that exhibited ductile response. The paper ends by describing a simplified method for use in design. The mechanics-based model and the design method yield an effective column lateral stiffness that closely aligns with the values obtained from the column database.
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