Seismic Design Parameters for Special Masonry Structural Walls Detailed with Confined Boundary Elements

In this paper, the results from a test program focusing on the behavior of eleven fully grouted reinforced masonry (RM) structural walls containing confined boundary elements are analyzed and presented according to force, displacement, and performance-based seismic design considerations. To be consistent with current force-based seismic design codes, analysis is presented to predict the strength, stiffness, displacements, and ductility-related force modification factors using the eleven test specimens. A new estimate of the plastic hinge region for displacement calculations is also proposed which considers the inherent planes of weakness in masonry mortar joints as well as the angle of inclination of shear cracks. Finally, within the context of performance-based design methodologies, the occurrence of specific damage states is identified. A methodology is proposed to estimate crack width in the walls based on curvature measurements which is also verified using digital image correlation analysis. The paper presents key seismic design parameters that are expected to contribute to the adoption of RM walls with boundary elements in the next-generation of North American seismic design codes.