Basic mechanisms for hybrid masonry structures

A relatively new innovative concept in building construction known as "hybrid masonry" combines conventional steel framing with reinforced concrete masonry structural panels. The system has been used for construction of several low-rise buildings in the eastern and mid-western United States, but has not been implemented in regions of moderate or high seismicity as yet. Unlike a traditional masonry infill-frame system, hybrid masonry panels are explicitly designed as structural elements rather than as an afterthought or non-structural element. The masonry panels can be treated as a surrogate for conventional steel bracing at a far reduced construction cost. As well, masonry panels can be designed to stiffen a bare frame so that performance-based objectives of immediate occupancy can be met for low levels of seismic input, and to provide sufficient lateral strength so that life-safety and collapse-prevention objectives can be met for moderate to high levels of seismic input. Before hybrid masonry can be fully embraced as a seismic structural solution, a simple understanding and confirmation of how it responds to reversed lateral forces is needed. The purpose of this paper is to briefly describe hybrid masonry, its basic governing mechanisms, the impediments to its implementation, and research needs. A new research project is described that will test the concept of hybrid masonry and provide the necessary confirmations for its practical implementation.