Report No.:
CCEER-01-4
- Analysis and Retrofit of Fixed Flared Columns
- With Glass Fiber-Reinforced Plastic Jacketing
Authors: M. Saiidi, J. Mortensen and F. Martinovic
Date: August 2001
- Sponsoring Agency: Nevada Department of Transportation (NDOT)
- Performing Organization:
- Department of Civil Engineering/258
- University of Nevada, Reno
- Reno, NV 89557
- Abstract:
- The main objectives of this study were to develop and analyze a
seismic retrofit method for flared columns that are fixed at both ends
and consist of a structural flare. The columns of Bridge I-1556 located
in Sparks, Nevada, were used in the study. A previous study of the
columns with respect to the seismic requirements had shown that the
confinement steel is inadequate and the shear capacity near the base of
the columns is marginal. Both of these deficiencies were addressed by
using a glass fiber-epoxy jacket. Because the columns are flared, a
continuous wrap over the flared segments is not appropriate. Therefore,
for the flared segments, a series of overlapping straps were recommended
. The FHWA and ACI procedures were used in design of the composite
jacket. To determine the effectiveness of the retrofit, the as-built and
retrofitted columns were analyzed for earthquakes loading using a nonlin
ear response history analysis computer program called RC-Shake. This
program accounts for stiffness and strength degradation of reinforced
concrete elements under cyclic loads. The 1994 Sylmar-Northridge
earthquake record was used. It was found that the retrofit reduced
the displacement ductility demand by 50 percent under an earthquake
with PGA of 1.2g.