In-Plane Performance of Unreinforced Concrete Masonry Strengthened with Prestressed GFRP Bars

This research investigates the feasibility of using prestressed glass fiber reinforced polymer (GFRP) bars for enhancing the in-plane shear strength of unreinforced masonry (URM) walls. In this application, URM walls were strengthened with prestressed GFRP bars by using the near-surface mounted reinforcement (NSM) technique. Prestressed GFRP bars would be used for repointing/closing wide open cracks in existing masonry structures. In total, eight URM walls were tested under in-plane diagonal compression. Experimental results validated the higher shear capacity of the strengthened URM walls and this increase was more pronounced for walls strengthened with prestressed GFRP bars. Furthermore, the calculated drift ratio in strengthened walls was considerably higher when failure was along stair-stepped diagonal cracks. Experimental results were used to modify and calibrate a theoretical shear friction model for predicting the in-plane shear capacity of strengthened URM walls with NSM prestressed GFRP bars. The model was capable of predicting reasonably well the shear capacity of strengthened URM walls.