Canada/US (CANUS) Comparison of Reinforced Masonry Shear Wall and Seismic Design Provisions

As part of a larger project titled, CANUS: Harmonization of Canadian and American Masonry Structures Design Standards Project, in this paper, the design provisions in TMS 402-16 and CSA S304-14 are compared for reinforced concrete masonry shear walls subject to in-plane forces. The scope of the work covers inplane bending and axial force interactions, shear capacity calculations, and seismic provisions for fully grouted reinforced concrete masonry shear walls. Seven parametric studies and two case studies are utilized to quantify the impact of some of the differences. The parametric studies include exploration of the effects of the wall aspect ratio, compressive strength of masonry, maximum reinforcement limitations and ductility requirements, material or capacity reduction factors, maximum compressive strain, and the artificial moment arm reduction considerations, as well as seismic wall categories and prescriptive seismic detailing requirements. The authors find that in most cases, the Canadian approach is more conservative than the U.S. The main contributor to this discrepancy is a large difference in the typical masonry compressive strength (f’m) values used in Canada and the U.S. By contrast, the maximum reinforcement ratio combined with a lower maximum strain in U.S. design can limit the height of reinforced masonry walls, especially in high seismic areas. The main product of this project is a list of potential future research studies for the resolution of some of the issues highlighted in this paper that can help improve and harmonize both countries’ masonry design provisions.