Thomas C. J. Vachon, and Lisa R. Feldman
Thomas C. J. Vachon, M.Sc. Student, Department of Civil, Geological, & Environmental Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK, Canada, thomas.vachon@usask.ca
Lisa R. Feldman, Professor and Director, Saskatchewan Center for Masonry Design, Department of Civil, Geological, & Environmental Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK, Canada, lisa.feldman@usask.ca
ABSTRACT
The χ-factors as included in Clauses 10.2.6 and 11.2.1.6 of CSA S304-14 – Design of Masonry Structures account for anisotropy and grout continuation in concrete block masonry construction
by reducing the resulting capacity of the flexural compression strength for members where loading is oriented parallel to bed joints. These factors were incorporated based on the results of experimental research programs. However, more recent research suggests that these χ-factors are overly conservative and so may lead to uneconomical designs. A test database was therefore assembled based upon experimental results as reported in the literature, and, of the 211 total specimens as included, was reduced to include data from 62 reinforced concrete block masonry
members representing cases in which block webs interrupted the depth of the compression stress block and loading was applied normal to the head face. A resulting analysis showed that the χ-
factor of 0.5 as currently included in CSA S304-14 for such scenarios may be more reasonably increased to 0.7 while still ensuring that adequate structural safety is provided. Additionally, this review highlighted the fact that past experimental programs neglected to include direct comparisons of geometrically similar wall and beam specimens with equivalent arrangements of
reinforcing steel and so provided the motivation for an updated experimental program as is currently underway at the University of Saskatchewan.
KEYWORDS: reinforced concrete block masonry, flexural compressive strength, direction of loading, web interruption, χ-factor
