Comparative analyses of reinforced masonry and reinforced concrete shear walls with different end configurations: Seismic performance and economic assessment

Abstract

Recent research has been demonstrating that fully-grouted reinforced masonry (RM) shear walls possess high ductile capacity levels that resulted in excellent performance under seismic loading. Considering the results of these studies, the current ductility modification factors assigned to such shear walls in relevant building codes and design standards are excessively conservative compared to the corresponding higher values assigned to their reinforced concrete (RC) counterparts. These conservative factors are mainly attributed to the lack of research studies that have been conducted to present direct comparisons between the performance of the two seismic force-resisting systems. To address this current knowledge gap and guide future editions of their relevant design standards based on experimental and analytical evidence, the objective of the current study is to show detailed comparative analyses between the performance of several RC and RM shear walls with different end configurations when both wall systems are subjected to similar seismic demands. These analyses also include a comprehensive economic assessment to equip practicing engineers and other relevant stakeholders with detailed comparisons between the two wall systems in terms of their construction costs. In this respect, six half-scaled RC shear walls were compared to three half-scaled RM shear walls, where all nine walls were tested under a quasi-static cyclic fully-reversed loading. The six RC shear walls were tested in two phases, where each phase consisted of three different wall types (i.e., rectangular, flanged, and boundary element walls) that had identical dimensions to their RM counterparts. To allow for direct comparison between the walls, Phase I RC walls with low vertical reinforcement ratios had similar lateral strength capacities as the RM walls, whereas Phase II RC walls with high vertical reinforcement ratios had similar ultimate curvature values as the RM walls. The comparison results are presented in the current study in terms of the crack patterns, load–displacement envelopes, curvature profiles, and wall displacements. Displacement ductility values, normalized periods, and equivalent viscous damping ratios are also presented for the nine walls. Finally, an economic assessment is performed to compare the walls in terms of their total rebar weights and approximate construction costs. The results demonstrate that RM shear walls can achieve an enhanced seismic performance similar to that of RC shear walls if the former walls are well-detailed (e.g., adequate confinement). Such an enhanced performance of RM shear walls is also coupled with low construction costs when compared to their RC counterparts. The current study enlarges the database of results that will facilitate assigning effective seismic performance metrics (e.g., ductility-related force modification factors) for RM shear wall buildings in future editions of building codes and design standards.