Strengthening of a concrete masonry wall subject to lateral load with sprayed glass-fibre-reinforced polymer

Unreinforced hollow concrete masonry walls could be used to construct basements if strengthened to resist the lateral load. Two face-shell-bedded concrete masonry walls were constructed, 3 m high by 6 m long. As a simple strengthening technique, one wall was sprayed with glass-fibre-reinforced polymer (GFRP) on one side to a nominal average thickness of 5 mm. The walls were subjected to distributed point loading simulating increasing pressure from top to bottom of the wall. Support conditions were applied to simulate the walls being part of a basement. The plain wall failed with a failure line cracking pattern at a lateral load of 44 kN. The sprayed wall failed in a much more brittle fashion when the load reached 330 kN. The GFRP suffered a mode III tear at the bottom course. The results indicate that spraying a plain masonry wall with GFRP increases its ability to resist lateral load considerably, and that the process could be improved in terms of both the thickness of the layer and the area of wall covered to achieve a specific target. The two walls were analyzed using the yield-line, fracture-line, and failure-line methods. The failure-line method was improved by accounting for the stiffness orthotropy of masonry and gave the most accurate prediction of these plastic design methods. A finite element model of the masonry provided the most accurate prediction of capacity.