LAUSR

Abstract Fiber reinforced cementitious matrix (FRCM), a noncorrosive two-dimensional high strength fiber reinforced polymer (FRP) mesh saturated with inorganic cementitious mortar is evolving as a viable option for retrofitting damaged RC structures . While numerous studies investigated the potential of FRCM strengthening in shear and flexural applications, limited studies explored the confinement of short and slender columns, particularly using finite element (FE) analysis. In this study, a three-dimensional (3D) nonlinear finite element (FE) model is developed using ABAQUS to study the behavior of corrosion damaged RC columns retrofitted with poly-paraphenylene-ben-zobisoxazole (PBO) FRCM systems. Geometric and material nonlinearities in concrete, cement mortar and composite are incorporated in the FE model that is validated through axial capacity and failure mode comparisons against published literature. A comprehensive parametric study involving 180 models is conducted considering the effects of five parameters: (a) cross section type (square vs circular), (b) FRCM wraps (1, 2, 3 and 4 layers), (c) pre-damage level (mild, moderate and severe), (d) eccentricity ratio (0.0, 0.3, 0.5, 0.75, 1.0, 1.25 and 1.5) and (e) column length (short and slender). Concrete compressive strength of 30 MPa and a longitudinal reinforcement ratio of 2% are adapted in all models. Results indicated that retrofitting corrosion damaged RC columns with PBO-FRCM effectively resorted and enhanced the original axial capacity and ductility of all column specimens and at all damage levels. A positive correlation between number of FRCM layers and axial capacity and ductility enhancement was observed and was more pronounced in circular columns. Increasing the number of FRCM layers also increased the axial capacity of eccentrically loaded columns irrespective of damage level and eccentricity ratio. Finally, comparison of axial capacity using ACI 549.4R-13 provisions against FE results disclosed that the code provisions underestimated the axial capacity of short RC columns retrofitted with PBO-FRCM by about 20%.