Parametric 3D finite element analysis of FRCM-confined RC columns under eccentric loading

Abstract

Fiber reinforced cementitious matrix (FRCM) is emerging as a viable retrofit and confinement technique, in lieu of fiber reinforced polymer (FRP) system which suffers from a number of issues related to the use of synthetic binders. While many studies have been conducted on the use of FRCM in shear and flexural applications, few were dedicated to confinement of slender columns, particularly those related to finite element (FE) analysis. In this study, a nonlinear three-dimensional FE model has been developed to study the behavior of reinforced concrete (RC) columns confined by (FRCM) jackets, and loaded concentrically and eccentrically. Drucker-Prager (DP) concrete model, which has several improvements over traditional DP models, was used to model the concrete core. Composite failure in the fibers comprising FRCM system and column buckling were also considered in the developed FE model. The model was validated by comparing its predictions with those of three control and 8 FRCM-confined RC columns from literature. Consequently, a parametric study utilizing 96 additional models, was performed on five parameters, namely: cross-sectional shape (square, circle, hexagon, and octagon), and for rectangular columns; aspect (h/b) ranging from 0.5 to 3, at 0.5 increment; slenderness (KL/r) ratio, considering four values, 10, 25, 50, and 75; load eccentricity (e) as a ratio (e/h) to side length (h), varying from 0 to 2.5; and concrete compressive strength (f́c), studying three values: 20, 35, and 50 MPa. Effects of these parameters on the column’s maximum load (Pmax) and general behavior, are discussed in details in Section 6 and summarised in the conclusions part. In general, Pmax increased by 0–32% as a result of applying one layer of FRCM jacket, and showed great dependence on the examined parameters.