Will Pahl, and Lisa Feldman
i M.Sc. Student, University of Saskatchewan, Saskatoon, Canada, wrp447@mail.usask.ca
ii Professor and Department Head, University of Saskatchewan, Saskatoon, Canada, lisa.feldman@usask.ca
ABSTRACT
The current standards governing concrete masonry unit (CMU) geometry in Canada and the United States are CSA A165-14 – Concrete Masonry Units and ASTM C90-24 – Standard Specification for Loadbearing Concrete Masonry Units, respectively. Starting with its 2011 edition, ASTM C90 allows for a minimum web thickness of 19 mm irrespective of CMU size. In contrast, CSA A165 has maintained historically used minimum web thicknesses that increase with CMU size, starting at 26 mm for 100 mm nominally sized CMUs. The reduced CMU weight resulting from minimizing web geometry reduces the likelihood and severity of workplace injuries to masons. Additionally, the use of thinner webs increases the energy efficiency of masonry walls. Webs are responsible for the transfer of shear forces within masonry assemblages. However, limited information was identified during a literature review relating to out-of-plane shear behavior and test
methods for shear transfer in masonry assemblages. A recent experimental investigation at the University of Saskatchewan showed that grout columns in partially grouted and reinforced walls as typically constructed obscured the behavior of the CMU webs. This paper therefore provides the background and experimental design of a novel investigation underway at the University of Saskatchewan. Walls with unbonded reinforcement anchored at their top and bottom are being constructed and subject to out-of-plane loading to evaluate the shear capacity of CMUs with varying web geometries. The use of unbonded reinforcement isolates the effect of varying web geometry on shear capacity. Four CMU geometries are included for evaluation: regular stretcher CMUs meeting the minimum web thickness requirements specified in either CSA A165 or ASTM C90, and two types of knock-out CMUs. The experimental investigation as described herein will begin in Spring 2025.
KEYWORDS: Concrete masonry units, out-of-plane loading, shear, web geometry, unbonded reinforcement.
005-Pahl.pdf
