Title:
Seismic Shear Strength of Circular Reinforced Concrete Columns
Author(s):
Ang Beng Ghee, M. J. N. Priestley, and T. Paulay
Publication:
Structural Journal
Volume:
86
Issue:
1
Appears on pages(s):
45-59
Keywords:
columns (supports); ductility; dynamic loads; flexural strength; earthquake-resistant structures; lateral pressure; reinforced concrete; shear strength; structural design; tests; Structural Research
DOI:
10.14359/2634
Date:
1/1/1989
Abstract:
The need for a consistent seismic design philosophy to establish design shear forces for reinforced concrete columns of bridges and buildings under seismic attack is discussed. It is shown that because of a combination of the effects of conservatism in flexural strength design equations and approximations in representation of seismic loads for analysis purposes, real shear forces generated during earthquakes may exceed three times the shear corresponding to code levels of seismic lateral loads. Existing U. S. and New Zealand design expressions for shear strength of circular columns are discussed and compared with results from a comprehensive test program involving 25 circular columns tested under axial load and cyclic lateral inelastic displacements. It is shown that existing design equations are inconsistent and very conservative for initial shear strength. The experimental results indicate, however, that the shear strength reduced with increasing flexural ductility for displacement ductility factors in excess of two. A model is presented for the influence of flexural ductility on shear strength applicable for low flexural ductilities and for fully ductile flexural designs.