Use of carbon fiber reinforced polymers for the repair of impact damaged prestressed concrete bridges
As a result of frequent vehicular collisions to prestressed concrete (P/C) bridge structures around the state of Iowa, a project was begun to investigate the capabilities of carbon fiber reinforced polymers (CFRP) as a method to repair and/or strengthen damaged bridges. A full-sized P/C beam was tested in the laboratory. Impact damage was simulated by removing a section of the bottom flange as well as cutting two prestressing strands, and the beams were repaired using a standard mortar and CFRP. The beam was subjected to cyclic loading simulating traffic before being statistically tested to failure. The load testing showed that the CFRP increased the cracking load and restored a portion of lost flexural strength. Three bridges, southbound I-65 near Altoona, Iowa; westbound IA-34 near Osceola, Iowa; and westbound I-80 near De Soto, Iowa were damaged by impact of overheight vehicles. They were load tested in their damaged condition and then repaired using CFRP. The Altoona bridge was retested to observe the differences in strains and deflections, and some of the results showed minor improvement from the damaged to the repaired tests for certain heavier load cases. A design/application guide was developed based on the Osceola Bridge work for design using CFRP and to provide documentation for repair. This includes a working design software template as well as a design example of a previously designed repair.