Structural behaviour of fabric reinforced cementitious matrix (FRCM) strengthened concrete columns under eccentric loading

The structural behaviour of eccentrically loaded reinforced concrete columns with rectangular crosssections strengthened with a cement based composite materials wrapping system, is analysed in thepaper, both experimentally and analytically.The main issues focussed in the paper were: i) the effectiveness of the cement based wrapping systemsto improve the strength of the reinforced concrete columns, ii) the influence of the load eccentricity andthe reinforcement ratio on the structural response of wrapped columns, iii) the prediction, by ananalytical procedure, of the structural behaviour of wrapped columns.A total of 8 reinforced concrete columns with end corbels, wrapped with fabric meshes of PBO (short ofPolypara-phenylene-benzo-bisthiazole) fibers embedded into a cement based matrix (PBO-FRCMsystem), were tested varying both the reinforcement ratio, rf, and the eccentricity-to-section height ratio(e/h). The influence of mechanical and geometrical parameters on the structural response of wrappedcolumns was analysed in terms of failure modes, strength and ductility.To predict the structural response of wrapped columns, a non linear second-order analysis that takesinto account the changes in geometry caused by lateral deformations is, also, developed. Theoreticalresults were compared with experimental ones to validate the effectiveness of the proposed procedure.