Strengthening masonry columns: steel strands versus FRP

Masonry structures are prone to brittle failure due to seismic forces or compressive overloads. A novel retrofitting technique is presented for the confinement of masonry columns subjected to compressive loads. The use of steel strands immersed in a cementitious matrix is described in terms of the mechanical properties of steel-confined columns. The structural behaviour of steel-confined columns was also compared with that of fibre-reinforced plastic (FRP)-confined columns. Experimental results showed the effectiveness of the proposed technique in terms of structural efficiency and installation procedure. The mechanical behaviour of steel-confined masonry and FRP-confined masonry was found to be very similar. The advantages of the proposed techniques with respect to confinement with FRP consist of the use of a cementitious matrix that does not require specialised labour and dry surface, allows moisture migration through the masonry surface of the column, is not prone to premature degradation or debonding under fire events, and is easily removable with mechanical tools without damaging the masonry core.