STRENGTHENING OF MASONRY WITH NEAR SURFACE MOUNTED FRP BARS

ABSTRACT

For the retrofitting of the civil infrastructure, an alternative to Fiber Reinforced Polymer (FRP) externally-bonded laminates is the use near surface mounted (NSM) FRP bars. This technique consists of placing a bar in a groove cut into the surface of the member being strengthened. The FRP bar may be embedded in an epoxy- or cementitious-based paste, which transfers stresses between the substrate and the bar. The successful use of NSM FRP bars in the strengthening of concrete members has been extended to unreinforced masonry (URM) walls, one of the building components most prone to failure during a seismic event. This paper describes three applications of FRP bars for the strengthening of URM and reports on the obtained experimental results. In the first application, FRP bars are applied vertically to resist out-of-plane forces acting on the masonry walls (i.e. flexural strengthening). In the second application, bars are inserted horizontally in the masonry joints to strengthen the wall when subjected to in-plane forces (i.e. shear strengthening). Finally, the third application deals with the retrofitting of masonry walls showing deficient anchorage to the base beam. In this application, FRP bars are placed in the toe region of the wall acting as anchors to increase flexural capacity. In each of these three applications, the strengthening was remarkably effective.