Behavior of Confined Masonry Walls with Openings under In-Plane and Out-of-Plane Loads

Six half-scaled wall panels were tested to investigate the effect of openings on their load-carrying capacity; these walls were subjected to a sequence of slow cyclic in-plane drifts and shake table-generated out-of-plane ground motions. Two specimens were masonry-infilled frames with and without openings. The other four specimens were confined-masonry (CM) walls, with one solid wall and three walls with openings bounded by reinforced-concrete (RC) confining elements on all sides. The infill walls demonstrated higher risk of out-of-plane collapse, whereas the CM walls maintained structural integrity and out-of-plane stability. The test results clearly indicate the necessity of confinement all around the openings for good seismic performance. The confining scheme with no continuous horizontal bands was ineffective in confining wall piers at large drifts, and piers remain vulnerable to out-of-plane collapse due to severe damage. However, the wall with continuous horizontal bands at the lintel and sill levels was not only able to compensate for deficiencies in strength due to the presence of openings, but also achieved a better overall behavior due to more distributed damage and greater ductility.