Due to their good sound and thermal insulation properties, unreinforced masonry (URM) walls are widely used in partitioning many of the commercial and residential buildings worldwide, either as in-fill or stand-alone. URM is considered one of the most common types of partition wall systems in many of the mid-age, low-rise to mid-rise, school and hospital buildings in North America. URM is still a very common and major building material, in many of the developing countries, being used in many

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... idential and commercial buildings. URM partition walls are known to have very low drift capacity in seismic events and the failure mechanisms are known to be mostly brittle and of catastrophic nature, during earthquake ground motion. Compared to other partitioning systems, URM walls tend to perform poorly during earthquake events, leaving many injuries, casualties, and fatalities behind. This dissertation elaborates on development of a novel, effective, and practical methodology for a robust out-of-plane seismic strengthening technique toward seismically upgrading URM partition walls, using a thin plaster layer of sprayable Ecofriendly Ductile Cementitious Composite (EDCC). The EDCC layer is devoted to secure such walls, which exist in most parts of the world; specially, in developing countries, where world's most population density is concentrated. In many of these countries, retrofit is the only option, since building replacement is not practical nor an economically feasible solution. The EDCC material can be applied in three different methods: hand troweled, hopper sprayed, or pump sprayed. The thickness of the layer can vary between 10mm to 20mm, depending on the design variables. iv Full-scale URM walls are built, strengthened, and tested on a shake table, using the strongest real historical earthquake records. The EDCC layer is providing nearly full out-of-plane detention for the wall's building blocks, as well as minor but uniform shear capacity enhancements for the in-plane action; therefore, holding the masonry units together from falling apart and being thrown during an earthquake generated ground motion. The newly developed high performance material is sprayable, ductile, and resilient, while being affordable, and easy to apply, with much less carbon footprint compared to other similar repair materials. v Lay Summary Every year hundreds of thousands of lives are taken away worldwide by natural disasters such as earthquakes. Walls made of concrete blocks or bricks, are amongst the most vulnerable type of walls, which tend to collapse during an earthquake. Debris from collapsing walls fall on pedestrians and building occupants, leaving behind a great deal of injuries and fatalities, even if the building frame is still standing. This research work has been devoted to develop an effective, practical, and affordable technology to help secure such walls, which exist in most parts of the world and, specifically, in developing countries, where the world's highest population density is concentrated. Through this doctoral work, a novel sprayable material, called Ecofriendly Ductile Cementitious Composite (EDCC), has been developed, used to strengthen real-scale versions of such walls, which were subsequently tested on a shake table, using the strongest actual historical earthquake records. The developed technology aims to save millions of lives worldwide. vi