RC-1386, Michigan Department of Transportation, Lansing, Michigan. Executive Summary Many bridge columns in Michigan are damaged by chloride contamination resulting in the corrosion of the steel reinforcement, and swelling and spalling of the concrete and use of the bridges is typically continued. This in itself may not be a serious problem since most columns in Michigan are over-designed and the loss of strength is not a significant issue. However, the lack of any method to minimize or prevent corrosion of the steel results in continued deterioration and unsightly columns. They offer a rapid repair technique with the potential to enhance the long-term durability and compression strength of damaged columns due to the confinement that is provided when fibers are oriented in the hoop direction.
Fibers oriented in the vertical direction can enhance the bending strength.
Experiments were conducted to assess the effects of using FRP wraps with fibers oriented in the hoop direction for rehabilitating corrosion-damaged columns. For round specimens, glass and carbon wraps increased the strength by a factor of about 2.3 and 2.6, respectively. For square specimens, glass and carbon wraps increased the strength by a factor of 1.4-1.5. Freeze-thaw conditioning generally reduced the longitudinal failure strain of wrapped specimens. The square wrapped specimens had lower compressive strength compared to the round specimens, even though the cross sectional area of the square prisms is higher than that of the round cylinders.