Effectiveness of Rehabilitation on Seismic Behavior of Masonry Piers

This paper summarizes research done to evaluate the effect of axial compression on unreinforced brick masonry (URM) walls and various rehabilitation techniques for enhancing seismic performance of URM structures. Flexural behavior of slender piers subjected to repeated and reversed in-plane deflections, and varied axial compression, is summarized relative to FEMA 356. The effectiveness of four rehabilitation techniques for improving seismic resistance are examined: (1) adhered fiber-reinforced polymer strips; (2) reinforced shotcrete overlay; (3) ferrocement surface coating; and (4) grouted reinforcing bars within drilled cores. The effectiveness of each technique is judged relative to the lateral strength and ductility of control piers with no rehabilitation, which are governed by a nonlinear, elastic rocking mode of behavior. Experimental results suggest that rocking behavior may be equal to, or superior to that of retrofitted piers because of the large ductility capacity at the component level. Test results also indicate that the FEMA 356 document conservatively characterizes seismic capacity for both nonrehabilitated and rehabilitated unreinforced masonry piers.