Discontinuous CFRP-jacketing of masonry columns

Existing masonry columns are often susceptible to cracking due to overloading. Moreover, their fragility under earthquakes’ forces is of particular concern in seismic-prone regions. In order to mitigate these structural deficiencies, Fiber Reinforced Polymers (FRPs) are commonly used for external confinement. Full-jacketing, by means of FRP-wrapping is recognized to be very effective in improving the load bearing capacity and the ductility of masonry columns. Unfortunately, long-term effects seem to be detrimental for the masonry core, since its breathability is obstructed by the polymeric resin. Thus, a discontinuous application of the FRP-confinement appears to be more indicated in stone-masonry columns, allowing the humidity cycles to recur. On the other hand, the discontinuous wrapping negatively affects the confinement effectiveness, since both confined and unconfined masonry regions participate in the bearing capacity. In this sense, the present research is aimed to study the discontinuous confinement of half-scale masonry columns by means of Carbon-FRP strips. Unconfined and confined specimens were tested under uniaxial compression. The CFRP-confinement was studied by investigating the lateral strain in the confined and unconfined portions of the specimens. The results are reported and discussed in the paper in terms of failure modes, axial stress-strain and axial stress versus lateral strain relationships. The outcomes are reasonably convenient for a proper analytical interpretation of the phenomenon.