DOE OSTI2011
This paper presents a strengthening technique for traditional load-bearing stone masonry walls. The technique consists in the application of GFRP strips on masonry wall faces, bonded to the substrate and further connected to it through mechanical anchorages. The effectiveness of this technique is highly dependent on the capability of developing high stresses on the composite reinforcement, which, in turn, depends on bonding and anchorage effectiveness. For this reason, an extensive experimental program devoted to the study of interface bonding was conducted. An innovative test setup was developed, consisting of modifications carried out on the “beam test” configuration, with the use of a dummy steel block, thus leading to a reduction of the number of manufactured masonry blocks. A total number of 29 specimens were tested, varying, amongst other things, the number and spacing of anchorages. As a general conclusion of the experimental program, it can be stated that the existence of anchorages proves to be highly beneficial in increasing the strength and deformation capacity of strengthened masonry walls. Tests have shown that the strengthening technique is extremely effective, leading to high tensile stresses in the GFRP strips, which, in turn, led to premature failure modes in some of the tests. Specimens with multiple anchorages have shown higher deformation capacity than those with single anchorage. Maximum composite force showed no significant dependency on the anchorage spacing and a consistent decrease in strength in specimens subjected to cyclic load history was not identified. Increasing anchorage spacing may lead to debonding failure, whereas decreasing spacing leads to an increase in cost and workmanship. An intermediate spacing—in the order of magnitude of the wall thickness—is recommended.