Unreinforced masonry walls subjected to blast loading are vulnerable to collapse and fragmentation. The objective of this thesis is to conduct experimental and analytical research for developing a blast retrofit methodology that utilizes polyurea. A total of four unreinforced masonry walls were constructed and tested under various shock tube induced blast pressures at the University of Ottawa Shock Tube Testing Facility. Two of the retrofitted walls had surface-sprayed polyurea. The results indicate that the use of polyurea effectively controlled fragmentation while significantly increased the load capacity and stiffness of masonry walls. Polyurea proved to be an excellent retrofit material for dissipating blast induced energy by providing ductility to the system and changing the failure mode from brittle to ductile. Single degree of freedom (SDOF) dynamic analyses were conducted as part of the analytical investigation. The results show that the analytical model provides reasonably accurate predictions of the specimen response.

This creative project creates a preservation plan for Dwenger Hall, located on the campus of Saint Joseph's College of Rensselaer, Indiana. The building was designed by the college's first president and constructed by students of the college in 1907-08. Vacant since 1998, the building is an excellent example of decorative concrete block construction. Because of its architectural and historical significance, the building merits the attention to develop an appropriate preservation plan.The plan contains a physical and social history of the building placing it in the historic context of Saint Joseph's College. The history includes early activities of the college with specifics on the construction and use of Dwenger Hall. The plan also includes a physical description of the building in its current state. The final sections of the plan describe the existing conditions, and prioritize recommendations for the preservation of the building.The recommendations for preservation are designed to preserve the building in three stages; immediate work, mothballing, and minimal general reuse requirements. The Plan's goal is to emphasize the value of this architectural and historical landmark by defining what makes it significant and how to preserve it for future generations. / Department of Architecture

Unreinforced masonry walls subjected to blast loading are vulnerable to collapse and fragmentation. The objective of this thesis is to conduct experimental and analytical research for developing a blast retrofit methodology that utilizes polyurea. A total of four unreinforced masonry walls were constructed and tested under various shock tube induced blast pressures at the University of Ottawa Shock Tube Testing Facility. Two of the retrofitted walls had surface-sprayed polyurea. The results indicate that the use of polyurea effectively controlled fragmentation while significantly increased the load capacity and stiffness of masonry walls. Polyurea proved to be an excellent retrofit material for dissipating blast induced energy by providing ductility to the system and changing the failure mode from brittle to ductile. Single degree of freedom (SDOF) dynamic analyses were conducted as part of the analytical investigation. The results show that the analytical model provides reasonably accurate predictions of the specimen response.

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)