Confinement model for concrete wrapped with fiber reinforced cementitious mortar

Abstract

Fiber reinforced cementitious mortar (FRCM) improves the performance of fiber-reinforce polymer (FRP) by replacing the organic matrix (e.g., epoxy) with inorganic one, resulting in a more sustainable alternative with a much improved fire resistance. While numerous models have been developed for FRP-confined concrete, FRCM-confined concrete have not received nearly as much attention. This study introduces a design-oriented model for FRCM-confined concrete. The model is the first to be derived from a very large database comprising 139 experimental specimens with various geometric and material properties, complemented with additional 144 numerical specimens obtained from finite element (FE) analysis. A nonlinear three-dimensional FE model was developed and verified with experimental results. It was used to examine the effects of mortar compressive strength (fm) and thickness (tm), type of FRP fabric, number of FRCM layers (n), compressive strength of unconfined concrete (fco), and height-to-diameter ratio (H/D). Results showed that the confined concrete strength (fcc) increases linearly as fm and tm increase, for all examined n, fco, and (H/D) values. fcc also varies almost linearly with n for all fabric types. A statistical analysis was performed on the combined database and a semi-empirical confinement model was developed to predict the peak strength and corresponding strain. It provided much better statistical performance and correlation with results than existing models and included a special coefficient for the effects of mortar properties.