Title:
Relationship between Strain, Curvature, and Drift in Reinforced Concrete Moment Frames in Support of Performance-Based Seismic Design
Author(s):
Aidcer L. Vidot-Vega and Mervyn J. Kowalsky
Publication:
Structural Journal
Volume:
107
Issue:
3
Appears on pages(s):
291-299
Keywords:
limit states; performance-based design; reinforced concrete frames.
DOI:
10.14359/51663694
Date:
5/1/2010
Abstract:
Through the use of moment-curvature analyses, trends between strain and curvature for rectangular reinforced concrete (RC) sections are explored. Variables in the analyses included section dimensions, axial load ratio (ALR) and longitudinal steel ratio (?long). Curvature-strain relationships that depend on ALR and ?long are developed from the results. These expressions are subsequently used to develop equations to compute interstory drift as a function of material strains for RC moment frames. The resultant equations can be used in performance-based design approaches such as direct displacement-based seismic design to compute target drifts and system displacements based on concrete and reinforcing steel strains. The interstory drift equations were correlated against 54 frame building analyses using a fiber-based analysis program. The drift expressions are shown to be accurate to within ±12% and ±20% for steel tension and concrete compression strain, respectively. Lastly, the implications of the proposed expressions on current code-based drift and ductility limits are explored.