Title:
Seismic Upgrade with Carbon Fiber-Reinforced Polymer of
Columns Containing Lap-Spliced Reinforcing Bars
Author(s):
Kumar K. Ghosh and Shamim A. Sheikh
Publication:
Structural Journal
Volume:
104
Issue:
2
Appears on pages(s):
227-236
Keywords:
columns; confinement; ductility; lap splice; rehabilitation.
DOI:
10.14359/18535
Date:
3/1/2007
Abstract:
Existing reinforced concrete (RC) columns detailed with poor lap splices and inadequate transverse confinement reinforcement in the potential plastic hinge regions near beam-column joints, characteristic of pre-1970 design provisions, are found to be deficient for the strength and ductility demands imposed by earthquake loading. The work reported herein was directed toward the evaluation of the effectiveness of carbon fiber-reinforced polymer (CFRP) jackets in strengthening and repair of such columns under simulated earthquake loading. A total of 12 columns, six 356 mm (14 in.) diameter circular and six 305 mm (12 in.) square, were constructed and tested. The columns were 1.47 m (58 in.) long and had a 510 x 760 x 810 mm (20 x 30 x 32 in.) stub at one end with a construction joint at the interface and spliced longitudinal bars in the columns. The variables studied in this program included effect of the presence of lap splices, the effectiveness of CFRP in pre-earthquake strengthening and post-earthquake retrofitting of deficient columns, as well as effects of level of axial load, shape of column cross section, and transverse steel reinforcement details. The CFRP retrofitting technique was found to be effective in enhancing the seismic resistance of the columns and resulted in more stable hysteresis curves with lower stiffness and strength degradations as compared with the unretrofitted columns.