New Frp and Adhesive Materials for Strengthening Infill Masonry Structures

ABSTRACT: This paper explores the behavior of infill masonry structures strengthened with a new type of Fiber Reinforced Polymer (FRP) strengthening system with high fracture strain know as PET (Polyethylene Teraphthalate) and a new near-surface mounted (NSM) Carbon fiber strengthening system using a cementitious material as the adhesive as compared to a Glass Fiber (GFRP) strengthening system (with epoxy adhesive). An experimental program, comprising twelve unidirectional infill masonry wall specimens was conducted to investigate the behavior of PET, CFRP, and GFRP strengthening and various FRP anchorage systems. In all cases tested, strengthening increased the load carrying capacity by at least 60% and by as much as seven times that of the unstrengthened wall. The PET system developed large strains prior to failure, enhancing the ductility of the strengthened wall. The CFRP system was effective in increasing the load carrying capacity with either epoxy or cementitious adhesive. The key advantage to using the cementitious adhesive is to enhance the fire resistance of the strengthening system. The results of the experimental program are compared with the design guidelines from the American Concrete Institute’s ACI 440.7R-10, which is used for FRP strengthening of masonry structures but does not currently apply to infill walls. Several modifications to the design approach are suggested to expand their use to include infill masonry.