Flexural Strengthening of Substandard Reinforced Concrete Bridge Wall Piers with CFRP Systems under Cyclic Loads

Reinforced concrete bridge wall piers constructed according to older codes experience damage during earthquakes, which can lead to bridge collapse. Deficiencies include inadequate design and detailing of longitudinal and transverse steel reinforcement and deficient lap splices. Three wall piers were constructed using as-built reinforcement details conforming to pre-1973 requirements to evaluate flexural strengthening strategies. The first wall pier was used as the control specimen. The second wall pier was retrofitted using carbon fiber-reinforced polymer (CFRP) jackets and transverse CFRP anchors placed through the section for the confinement of the lap-spliced region and vertical CFRP anchors to improve flexural capacity. The third wall pier was retrofitted similarly to the second pier by using vertical near-surface mounted (NSM) CFRP rods. The piers were tested under cyclic lateral load until failure. Both retrofitted wall piers were able to achieve significantly higher flexural capacity, stiffness, and hysteretic energy dissipation when compared with the control wall pier specimen. The as-built wall specimen was not able to develop the theoretical flexural capacity due to lap splice clamping failure; both retrofitted specimens exceeded the theoretical flexural capacity of the as-built wall specimen.