Nader Aly and Khaled Galal
Nader Aly, Owner’s Engineering Lead, Bruce Power, ON, Canada. Formerly, Postdoctoral Fellow, Department of Building, Civil and Environmental Engineering, Concordia University, 1515 St. Catherine West, Montreal, QC, Canada, Nader.essam.aly@gmail.com
Khaled Galal, Professor, Department of Building, Civil and Environmental Engineering, Concordia University, 1515 St. Catherine West, Montreal, QC, Canada, khaled.galal@concordia.ca
ABSTRACT
The ductile type of Reinforced Concrete Masonry (RCM) shear walls was added in the 2015 edition of the National Building Code of Canada (NBCC-15) and was assigned a ductility-related
response modification (Rd) factor of 3.0. Recent experimental studies demonstrated the capability of ductile RCM shear walls with masonry boundary elements in attaining displacement ductility
capacity higher than their rectangular counterparts. The objective of this study is to quantify the essential force and displacement-based design parameters of RCM shear walls with masonry boundary elements based on all reported experimental test results. The considered experimental studies included quasi-static cyclic testing of flexural dominant walls that varied in the shear spanto- depth ratios, the vertical reinforcement ratios, the confinement of end zones, and the axial load ratios. Based on an analysis of the experimental results, a ductility-related modification (Rd) factor and a stiffness reduction factor are proposed. The proposed factors are compared with the values of North American masonry design standards. It is noted that RCM shear walls with boundary elements can be assigned higher Rd values than the current value specified in the Canadian masonry design standard (i.e., CSA S304-14). Besides, the stiffness reduction factor provided by CSA S304-14 was found to provide reasonable estimates of the cracked stiffness. However, it slightly overestimated the cracked stiffness for the walls with high aspect ratios. Nevertheless, such crucial design parameters cannot be solely derived based on an analysis of the component-level response. As such, the study will be extended to quantify the seismic response parameters based on the overall (system-level) characteristics. It will account for the different system-level aspects, such as the slab coupling, the contribution of orthogonal (out-of-plane) walls, and the level of ductility demand in individual walls.
KEYWORDS: RCM walls, boundary elements, ductility, effective stiffness, stiffness degradation
