Experimental study on seismic behavior of reinforced hollow concrete block masonry walls strengthened with carbon fiber sheets

In order to propose a retrofit method for improving the seismic behavior of existing reinforced hollow concrete block masonry walls with poor seismic resistance, four different bearing wall specimens with and without strengthening were tested under constant gravity load and repeated lateral forces. In the strengthened specimens, carbon fiber sheets are bonded to the surface(s) of concrete block wall panels by using epoxy resin. The test results obtained from three specimens in the first test series indicated that if the walls are strengthened by the carbon fiber sheets, then the ultimate lateral strength of the walls increase approximately 20 to 25 percent. However, the strengthened specimens failed in sliding failure mode at the connection part of wall and foundation beams and could not reach their ultimate shear strengths. In order to increase sliding resistance of the wall, anchor bolts were installed at the weakness part of another strengthened specimen. As the result, this specimen developed its ultimate shear strength, which is approximately 40 percent higher than that of the specimen without any strengthening.