Behavior and Design Aspects of FRP-Strengthened URM Walls under Out-of-Plane Loading

Abstract

The use of externally bonded fiber-reinforced polymer (FRP) composites for upgrading the out-of-plane flexural resistance of unreinforced masonry (URM) walls is experimentally and analytically investigated in this study. A total of six hollow concrete block walls were tested to failure using an airbag and a reaction frame to obtain a uniform load on the wall. The masonry walls were placed horizontally and tested as one-way slabs with span direction perpendicular to the bed joints. The first wall was left unstrengthened to be used as control specimen; the other five walls were strengthened using different schemes of externally attached glass-fiber-reinforced polymer (GFRP) sheets. The main parameters studied experimentally were FRP reinforcement ratio and stiffness. In addition to the experimental program, an analytical model was developed to predict the ultimate moment capacity of the URM walls. The procedure outlined in standard guidelines was also utilized to compute the flexural capacity of walls. Besides the URM wall specimens tested in this study, another 42 test results of URM walls available in literature were used for analytical model validation. A design model was also proposed and new design aspects were introduced.