An experimental study on the influence of composite materials used to reinforce masonry ring beams

For historic masonry constructions the out-of-plane wall behavior is critical to seismic performance. Because the main cause of out-of-plane collapses is the wall-to-wall level of connection, the application of a reinforced concrete (RC) ring beam at the eaves level of historic masonry buildings is an effective method to prevent an out-of-plane mechanism of a wall panel. However this effective reinforcing method presents some drawbacks. In order to address this, this paper describes the problems associated with this “traditional” reinforcing method and introduces a new retrofitting technique for historic masonry buildings by realizing a new type of ring beam made of recycled old stones or bricks reinforced at the bed joints with glass-fiber sheets, GFRP (Glass Fiber Reinforced Polymer) grids or/and PBO (polybenzoxazole: poly-p-phenylene benzobisoxazole) cords. An experimental investigation has been carried out on 10 full-scale rubble-stone or brickwork masonry ring beams. The testing included the use of composite materials inserted into the mortar joints during the fabrication phase of the beams and pinned end conditions (four-point bending configuration). Beams were reinforced with different composite layouts.