Influence of Web Geometry on Concrete Masonry Walls Subject to Out-of-Plane Loading
Date
2024-01-22
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0009-0001-3805-2231
Type
Thesis
Degree Level
Masters
Abstract
Concrete masonry walls are often required to resist out-of-plane loading from a variety of sources. The concrete masonry units (CMUs) used to construct these walls must have an adequate web geometry as the webs are responsible for the transfer of internal shear forces. However, reducing the area of web that connects the face shells of a CMU provides an increased thermal resistance and a decreased CMU weight. The minimum allowable web geometries for CMUs are specified in Canada and the United States in CSA A165 and ASTM C90, respectively. CSA A165 currently requires a larger web geometry than ASTM C90: minimum web thicknesses that increase with CMU size and range from 20 mm to 30 mm are specified in CSA A165, while a minimum web thickness of only 19 mm is specified in ASTM C90 regardless of CMU size. Furthermore, ASTM C90 allows for any combination of web height, thickness, and number of webs that meet both the minimum web thickness and a minimum normalised web area. CMUs with webs meeting the web geometry requirements specified in ASTM C90 have not been experimentally evaluated, and it is possible that they could experience premature web failure in masonry walls subject to out-of-plane loading.
An experimental program was therefore conducted to investigate the influence of web geometry on the structural performance of masonry assemblages and to determine the feasibility of reductions to the web geometry requirements in CSA A165. An investigation of the influence of web geometry on masonry walls subject to out-of-plane loading is described herein and was conducted as part of an overall program of study. Twenty-seven partially grouted, 13 course tall, 2.5 CMU wide, and reinforced concrete masonry walls were constructed and tested subject to four point out-of-plane loading. Web geometry, reinforcement ratio, and spacing of reinforcement were varied to create nine unique wall configurations. Crack patterns, applied loading, and deflections were recorded to allow for the determination of moment resistances, deflected shapes, ductility ratios, and post-cracking flexural stiffnesses. Test results were compared between walls and to a theoretical model. No instances of premature web cracking were identified and web geometry was not found to notably influence the behaviour of the walls. The results therefore support reductions to the web geometry requirements specified in CSA A165 pending further investigation.
Description
Keywords
CMU, Masonry, Out-of-Plane Loading, Web Geometry
Citation
Degree
Master of Science (M.Sc.)
Department
Civil and Geological Engineering
Program
Civil Engineering