Title:
Seismic Design and Behavior of Reinforced Concrete Columns With Interlocking Spirals
Author(s):
H. Tanaka and R. Park
Publication:
Structural Journal
Volume:
90
Issue:
2
Appears on pages(s):
192-203
Keywords:
columns (supports); ductility; earthquake-resistant structures; confined concrete; reinforced concrete; shear strength; spiral reinforcement; Structural Research
DOI:
10.14359/4125
Date:
3/1/1993
Abstract:
Transverse reinforcing details for concrete columns using interlocking spirals have been introduced in the standard specifications for highway bridges adopted by AASHTO:1977 and revisions by CALTRANS:1990. Those specifications are intended to insure ductile behavior of reinforced concrete columns subjected to severe earthquakes; however, those specifications are based on limited xperimental evidence. In this study, a series of methods to evaluate effectiveness of interlocking spirals as shear and lateral confining reinforcement is proposed. The adequacy of those proposed methods is assessed by carrying out cyclic horizontal loading tests on three columns with rectangular hoops and cross ties. All columns had a rectangular or near- rectangular cross section of dimensions 400 x 600 mm (15.7 x 23.6 in.) and the ratio of shear span length to overall depth of column section was 3. The tested columns with interlocking spirals were designed using the methods proposed and applying the provisions for columns with single spirals in the New Zealand concrete design code where those are applicable. All the measured lateral load- lateral displacement hysteresis loops showed good energy dissipation and limited reduction in strength up to the end of the test at a displacement ductility factor of more than 10. Thus, the adequacy of the proposed methods was verified as far as the columns tested were concerned.