Numerical modeling of deteriorated concrete bridge bent caps with externally bonded CFRP retrofit

Deterioration of old concrete bridge bent caps due to spalling and rebar corrosion is a common occurrence. Carbon fiber-reinforced polymer (CFRP) laminate external retrofit is a viable option for regaining such bent cap capacity and serviceability. In this study, a three-dimensional numerical modeling of significantly deteriorated bent caps from a 78-year old cast-in-place bridge in Forney, Texas, was performed. The purpose was to determine the effectiveness of the repair and strengthening process. Numerical models of the bent caps in the original undamaged, damaged, epoxy mortar repaired and CFRP strengthened states were created and calibrated using strain data obtained from full-scale live load testing. The calibrated model strains showed good agreement with those from the load testing. With short span lengths and deep sections, the model strains were small and the effect of the repair/strengthening at modest levels. The neutral axes of the bent cap sections, found from numerical modeling, moved slightly downward after the repair/strengthening process. The model with no section loss showed the highest tensile capacity, and subsequent levels of concrete spalling resulted in progressively smaller capacity. After the first crack initiation, inelastic behavior set in along with crack opening, which explains the increased rate of strains. Truck live loads were adequately represented in the developed numerical models.