Performance Evaluation of a Reinforced Concrete Slab Bridge Retrofitted with Carbon Fiber Reinforcement Polymer Laminate System

As a result of a drawing oversight, a nine-span continuous reinforced concrete slab bridge on westbound I-10 near Lordsburg, New Mexico, was built with only half of the required positive moment steel reinforcement. Bridge 9367, constructed in April 2006, was retrofitted with a carbon fiber–reinforced polymer (CFRP) laminate system in November 2006 to correct for this error. Diagnostic load tests were conducted before and immediately after the retrofitting of the bridge. A finite element analysis of the bridge was also conducted to evaluate the strength and serviceability of the slab bridge and to determine whether the addition of the CFRP system effectively met these limit states. The addition of the CFRP to the bridge increased the rating factors to greater than the legal load limit. Before the bridge retrofit, stresses in the steel reinforcement exceeded the limits set to control excessive concrete cracking and inelastic deformations. Inclusion of the CFRP reduced these stresses but only slightly below the limits. Creep rupture and fatigue of the CFRP were not considered issues. Two additional load tests were conducted 8 months and approximately 9 years after the retrofit. The first evaluation showed that in the short term, the slab stiffness was increased with a decrease in measured strains immediately after the installation of the CFRP. However, comparison of the strains from the load tests conducted later showed that the magnitudes had greatly increased and were approximately equal to the preretrofit strains. Ultimately, Bridge 9367 was replaced due to excessive cracking and large measured strains.