Effect of corner radius on the axial behavior of FRCM-confined concrete members

Recent research has shown that an increase in the axial strength of concrete compression members can be achieved with the confinement of such members by means of fibre reinforced cementitious matrix (FRCM) composites. Unfortunately, the available experimental evidence on the topic is still scarce, and a significant research effort is needed in order to fully understand the behaviour of FRCM-confined members. For instance, for the case of fibre reinforced polymer (FRP) composites it has been shown that the gain in strength is directly proportional to the corner radius of the elements. However, the influence of this parameter on the effectiveness of the FRCM-confinement has not been deeply investigated. Based on this need, the results of an experimental campaign on FRCM-confined concrete members with four different radius corners (i.e., four different cross-sections) tested under monotonic compression are presented in this paper. Values of axial strength of the confined members are compared to that of unconfined control specimens and the influence of the confinement and the corner radius in the gain in axial strength is discussed. In addition, the behaviour of the confined members is analysed in terms of type of failure mode attained depending on the corner radius of each specimen.