Case Study: Strengthening of Parking Garage Decks with Near-Surface-Mounted CFRP Bars

This paper describes a parking garage retrofitting project where near-surface-mounted carbon fiber-reinforced polymer (FRP) bars were used to strengthen the reinforced-concrete decks. The garage reportedly exhibited numerous signs of deterioration, such as excessive deflections of the decks at bay midspans, extensive concrete cracking, concrete spalling, etc. The results of the structural analyses indicated that several negative-moment slab regions were deficient to support the design loads. The amount of overstressing was up to 50% in some areas. The structural analysis considered as-built conditions and showed that deficiencies were predominantly due to misplacement of the negative-moment steel reinforcement. The paper summarizes the design approach for carbon FRP strengthening of the concrete decks and describes a load testing program used to evaluate their performance. Finally, a description of parameters and considerations used in development and implementation of the adopted strengthening strategy is also presented.