A performance-based approach to retrofitting unreinforced masonry structures for seismic loads

Abstract

The structural inadequacy of existing unreinforced masonry (URM) buildings to resist possible seismic loading is a serious problem in many parts of the United States, including the Northeast and Midwest. The fact that many of these buildings are deemed historic structures or house critical facilities, like firehouses, emphasizes the need for an effective retrofitting program. The Federal Emergency Management Agency published a performance-based design code - FEMA 356 - in 2000 to use for analyzing and retrofitting existing structures. This code includes procedures for URM buildings. This paper applies these performance-based analysis procedures to a URM shear wall and compares the results to a modified analysis proposed by researchers. The wall is then rehabilitated using two common retrofit methods and again analyzed using the code. Recommendations are made for practicing engineers when evaluating URM structures for seismic loads.