FRP wraps for the confinement of concrete members in compression

This paper deals with the behavior of short R/C members in compression, externally wrapped with carbon-fiber reinforced-plastic (CFRP) sheets. Some results of an experimental investigation on concrete cylinders and prisms with square and rectangular cross-section, externally wrapped with CFRP sheets are presented. The effects of the following parameters are investigated: (a) concrete grade; (b) type and arrangement of the longitudinal and transverse steel bars; (c) local reinforcement with CFRP strips at the comers and continuous layers; (d) horizontal and vertical discontinuous strips; (e) number of continuous layers; (f) length of specimens; and (g) specimen type (cylinders and prisms). The analytical methods for the determination of the bearing capacity of wrapped members recently proposed by CEB-FIP Bulletin and by the Italian Research Council CNR are presented and discussed. Moreover, the results obtained in recent experimental and analytical investigations by the author are also presented. These studies are focused on the determination of the bearing capacity of concrete members in compression, having circular, square, rectangular or elliptical cross-section and being externally-wrapped with FRP sheets, size effect included. Also a mechanical model recently proposed by the author for the evaluation of the bearing capacity of members with smoothed or sharp comers, reinforced with single or continuous wraps is presented and discussed.