Live Experimental Test
Thursday, September 3, 2009, 11:00 AM (PDT)
Emergency Repair of Damaged Bridge Columns Using Fiber Reinforced Polymer (FRP) Materials
OLS-R
(1/3-Scale Old-Design Low Shear Column)
Previous Experiments - NHS2 - NHS2-R - OHS - OHS-R - OLS
PI
M. Saiid Saiidi, Professor, Civil and Environmental Engineering
Graduate Research Assistant:
Ashkan Vosooghi, PhD Candidate
Sponsored by
California Department of Transportation (CalTrans)CalTrans Research Program Manager:
Dr. Saad El-Azazy
ABSTRACT
Past effort in the seismic design of concrete bridges has been on detailing of bridges to prevent collapse. During earthquakes, reinforced concrete bridge columns are designed to undergo cracking, spalling, and yielding of steel and provide significant rotational capacity at plastic hinges so that the integrity of the overall structure is maintained. With proper design and construction, this objective can be met. However, the serviceability of the bridge after the earthquake is in question. The level of damage to different columns of a bridge varies depending on the intensity of the ground shaking, type of earthquake, and the force/deformation demand on individual members. Based on the inspection of the damaged columns engineers have to determine whether the bridge is sufficiently safe to be kept open to traffic. They should also recommend repair methods for the columns. Any delay in opening of the bridge to traffic can have severe consequences on the passage of emergency vehicles, detour lengths, and traffic congestion in the area. Rapid and effective repair methods are needed to enable quick opening of the bridge to minimize impact on the community.
In this study, a one-third scale old design column which was damaged to the highest repairable level in the previous tests, was repaired using CFRP wrapping. At this level of the damage, major ring cracks merged to shear cracks appeared at the column base at the end of the lap splice. At the compression side of the column base, extensive spalling was observed.
The entire repair process consists of the following steps:
- Remove the loose concrete and repair the spalled area using a fast set / non shrink mortar.
- Pressurized epoxy injection of the cracks.
- CFRP wrapping.
- Curing.
The repaired column (OLS-R) is subjected to Sylmar earthquake with gradually increasing PGA, using one of the UNR shake tables and the mass-rig setup. The objective of the test is to evaluate the performance of the repair process.
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