Pages vi, 34, 68, 158, 208 and 226 are blank and therefore omitted. / <p> To assess the ductility of shear walls under earthquake loading, more experimental evidence is strongly needed. Ductile response can be achieved through the development of a flexural plastic hinge at the base characterized by yielding of the vertical reinforcement. The length of the plastic hinge and the ultimate curvatures within this region are the essential parameters affecting the ductility and ultimate displacements of reinforced masonry shear walls. The discrepancies in existing information regarding the length of plastic hinges and ultimate curvature may be attributed to the effects of many shear wall parameters such as distribution and amount of vertical and horizontal steel, level of axial load, and wall aspect ratio. </p> <p> The focus of this study was to evaluate the effect of different parameters on plastic hinge length, energy dissipation, and on general ductility of masonry shear walls. To address the aforementioned goal, six fully grouted reinforced masonry walls were tested under fully reversed cyclic lateral loading. All walls were designed to experience ductile flexural failure. The test matrix was chosen to investigate the effects of the amount and distribution of vertical reinforcement and the level of applied axial load on the lateral loading response and ductility of reinforced masonry shear walls. To examine the effects of these parameters, measurements of the applied loads, vertical and horizontal displacements as well as strains in the reinforcing bars were used to analyze the behaviour of the walls. Also, from these measurements, other quantities used in analysis were determined, including displacement ductilities, curvature profiles, energy dissipation and equivalent plastic hinge length. </p> <p> The results show high ductile capability in the plastic hinge region and very little degradation of strength for cyclic loading. High levels of energy dissipation in the reinforced concrete masonry shear walls were achieved by flexural yielding of the vertical reinforcement. All walls showed increasing hysteretic damping ratios with increase in displacement. Results showed that displacement ductility and energy dissipation were highly sensitive to increases in amount of vertical reinforcement but were less dependent on the level of applied axial stress. The results of this study also showed that the measured plastic zone length decreases with increase of the amount of reinforcement while it is almost the same for the different levels of axial stress. Based on the test results, it was shown that reinforced concrete masonry shear walls may be utilized in high intensity seismic areas with performance meeting or exceeding current expectations. </p> / Thesis / Master of Applied Science (MASc)

The current thesis focuses on estimating the damage levels and evaluating the out-of-plane behavior of fully-grouted reinforced masonry (RM) structural walls under blast loading, a load that they are typically not designed to resist. Twelve third-scale RM walls were constructed and tested under free-field blast tests. Three different reinforcement ratios and three different charge weights have been used on the walls, with scaled distances down to 1.7 m/kg1/3 and two different boundary conditions, to evaluate the walls’ performances. In general, the results show that the walls are capable of withstanding substantial blast load levels with different extents of damage depending on their vertical reinforcement ratio and scaled distance. It worth mention that the current definitions of damage states, specified in ASCE/SEI 59-11 (ASCE 2011) and CAN/CSA S850-12 (CSA 2012) standards, involve global response limits such as the component support rotations that are relatively simple to calculate. However, these quantitative damage state descriptors can be less relevant for cost–benefit analysis. Moreover, the reported experimental results showed that the use of quantitative versus qualitative damage descriptors specified by North American blast standards [ASCE 59-11 (ASCE 2011) and CSA S850-12 (CSA 2012)] can result in inconstancies in terms of damage state categorization. Therefore, revised damage states that are more suitable for a cost–benefit analysis, including repair technique and building downtime, were presented. These damage states are currently considered more meaningful and have been used to quantify the post-earthquake performance of buildings. In addition, a nonlinear single-degree-of-freedom (SDOF) model is developed to predict the out-of-plane behavior of RM structural walls under blast loading. The proposed SDOF model is first verified using quasi-static and free-field blast tests and then subsequently used to extend the results of the reported experimental test results with different design parameters such as threat level, reinforcement ratio, available block width, wall height, and material characteristics. In general, brittle behavior was observed in the walls with a reinforcement ratio higher than 0.6%. This is attributed to the fact that seismically detailed structural masonry walls designed to respond in a ductile manner under in-plane loads might develop brittle failure under out-of-plane loads because of their reduced reinforcement moment arm. In addition, increased ductility can be achieved by using two reinforcement layers instead of a single layer, even if the reinforcement ratio is reduced. Also, it is recommended to consider the use of larger concrete masonry blocks for the construction of RM structural walls that are expected to experience blast loads in order to reduce the slenderness ratio and for the placement of two reinforcement layers. Finally, a probabilistic risk assessment (PRA) framework is proposed in order to develop design basis threat (DBT) fragility curves for reinforced concrete block shear wall buildings, which can be utilized to meet different probabilities of failure targets. To illustrate the proposed methodology, an application is presented involving a medium–rise reinforced masonry building, under different DBT levels. The DBT fragility curves are obtained via Monte Carlo sampling of the random variables and are used to infer the locations, within the building premises, that are most suitable for the erection of barriers for blast hardening. / Thesis / Doctor of Philosophy (PhD)