Masonry infilled walls have been commonly used as interior partitions as well as exterior walls infilled in either steel or reinforced concrete frames in the modern building constructions. In recent years, much research involving both experimentation and numerical modeling has been conducted in an effort to better understand the infill-frame interaction and to provide some rational design approaches. Studies have shown that infill walls can develop a number of possible failure mechanisms, depending on the strength and stiffness of the bounding frames with respect to those of the infills and the geometric configuration of the framing system. Most of models proposed for analysis of infill walls focused on one type of mechanism or the other, and they were not universally applicable to all infilled structures.