Title: Seismic Load Tests on Reinforced Concrete Columns Strengthened by Jacketing

Author(s): M. Rodriguez and R. Park

Publication: Structural Journal

Volume: 91

Issue: 2

Appears on pages(s): 150-159

Keywords: columns (supports); concrete; ductility; flexural strength; earthquake-resistant structures; loads (forces); reinforced concrete; Structural Research

DOI: 10.14359/4593

Date: 3/1/1994

Abstract:
Four reinforced concrete column units were tested, subjected to simulated seismic loading to investigate repair and strengthening techniques. The as-built columns were 350 mm (13.8 in.) square and contained low quantities of transverse reinforcement, as was typical of building columns designed and constructed prior to 1970. The column units represented the column region between the midheights of successive stories. A stub was present at the midheight of each unit to represent a portion of the two-way beams and slab of the beam-column joint. Two column units were tested, repaired, and strengthened by jacketing and retested. The other two column units were strengthened by jacketing and tested. The jacketing consisted of a 100-mm (3.94-in.) thickness of added reinforced concrete. The new longitudinal reinforcement was placed through the floor slab. Two arrangements of transverse reinforcement in the jacket were investigated. The as-built columns displayed low available ductility and significant degradation of strength during testing, whereas the jacketed columns behaved in a ductile manner with higher strength and much reduced strength degradation. The retrofit of columns using reinforced concrete jackets was found to be successful but labor-intensive.