Twenty full-scale unreinforced masonry walls were constructed and tested to failure in the Structures Laboratory at the University of Saskatchewan. The focus of the testing related to two primary objectives. The first objective was to study the effects that the support conditions of the walls had on their behaviour. The masonry wall specimens tested spanned vertically under the application of out-of-plane loads. Ten of the full scale walls were tested with support conditions that modeled ideal pinned connections at the top and bottom of the wall, while the remaining half of the walls were tested with nominally “pinned” supports that were similar to the supports typically encountered in practice. The second objective was to determine the effects that dynamic loads had on the behaviour of the walls. Half of the masonry specimens for each group of support conditions were loaded laterally with monotonically increasing quasi-static loads representative of the effects of uniform wind pressure, while the remaining specimens were loaded laterally with dynamic time histories that varied randomly in a manner that was representative of real “gusty” winds. The research was therefore done to determine the influence of load and connection type on the behavior of the masonry walls. When comparing the effects of the support conditions, it was found that the walls constructed with realistic support conditions were able to resist larger out-of-plane loads, with greater ductility than the walls that had ideally-pinned supports. Specifically, the realistically-pinned walls required an average moment (of both the statically and dynamically loaded walls) that was 63% larger to cause mid-height cracking than the average mid-height moment required to cause mid-height cracking in the ideally-pinned walls. After mid-height cracking occurred, the realistically-pinned walls exhibited reserve capacity, resulting in additional strength, such that the ultimate moment capacity of the realistically-pinned walls was 140% greater than the ultimate strength of the ideally-pinned walls, where the ultimate strength was the capacity of the wall at mid-height cracking. As a result, the ductility of the realistically-pinned walls was also significantly larger than that of the ideally-pinned walls. Specifically, the ductility ratio of the realistically-pinned walls was 70 (where the ductility ratio is defined as the displacement at the ultimate load divided by the displacement at mid-height cracking), while the ductility ratio of the ideally-pinned walls was unity (the ultimate load coincided with formation of the mid-height crack). The results of the dynamically and quasi-statically loaded walls were harder to evaluate. In comparing the ideally-pinned walls it was found that the specimens that were loaded dynamically had an average moment capacity that was approximately 10% larger than the walls that were loaded quasi-statically, which was found to be statistically significant at the 90% level. However, the results from the realistically-pinned walls were not as conclusive. At mid-height cracking the dynamically loaded walls had an average moment capacity that was 24% lower than the quasi-statically loaded walls, which seems to contradict with the data from the ideally-pinned walls and from the literature suggesting that dynamic strengths should be higher. At the ultimate condition, the dynamically loaded walls had an average strength that was 12% larger than the quasi-statically loaded walls; however, these comparative results were not statistically significant at the 90% confidence level. It was also found that the dynamic loading failed the wall specimens as a result of sustained, large amplitude “gusts” rather than at the largest instantaneous peak load. The displacement behaviour of the walls was generally independent of the method of loading, but, rather, largely dependent on the support conditions. The collapse of the wall specimens were all initiated when they reached a geometrically unstable displaced shape that was fairly consistent for a given support configuration, regardless of the type of load that was applied. Lastly, results from a numerical model suggested that the dynamically loaded walls exhibited higher apparent stiffness properties as compared to the quasi-statically loaded walls. The difference in the apparent stiffness between the dynamic and quasi-static specimens decreased with increasing damage levels until the dynamic stiffness converged to the static stiffness near the collapse of the walls.

Cold weather masonry construction is a major concern for contractors as they either have to implement heating practices for laying and curing masonry systems or postpone the construction to warmer periods. This can lead to loss of productivity rate and delays in construction schedules with associated extra costs. This thesis explores a novel approach for mitigating the adverse effects of cold weather on masonry construction in early fall periods through the application of nano-alumina (NA) and nano-silica (NS) in mortar joints. The assessment criteria were based on the fresh properties, hardened properties and microstructural features of mortar mixtures and mechanical behaviour of concrete masonry prisms at early and later ages. Various test results show that NS can be successfully used to minimize the adverse effects of cold temperature on mortar joints by speeding up the hydration of cement, shortening the setting time, and increasing the strength up to 72 h.

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No description available.

Thesis (M.S. in civil engineering)--Washington State University, December 2008. / Title from PDF title page (viewed on Feb. 19, 2009). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 56-57).

Thesis (M.S. in civil engineering)--Washington State University, May 2010. / Title from PDF title page (viewed on July 14, 2010). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 72-73).

Thesis (M.S. in civil engineering)--Washington State University, May 2010. / Title from PDF title page (viewed on July 21, 2010). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 96-97).

Unreinforced masonry (URM) walls are commonly found in existing and heritage buildings in Canada, either as infill or load-bearing walls. Such walls are vulnerable to sudden and brittle failure under blast loads due to their insufficient out-of-plane strength. The failure of such walls under blast pressures can also result in fragmentation and wall debris which can injure building occupants. Over the years, researchers have conducted experimental tests to evaluate the structural behaviour of unreinforced masonry walls under out-of-plane loading. Various strengthening methods have been proposed, including the use of concrete overlays, polyurea coatings and advanced fiber-reinforced polymer (FRP) composites. Fabric-reinforced cementitious matrix (FRCM) is an emerging material which can also be used to strengthen and remove the deficiencies in unreinforced masonry walls. This composite material consists of a sequence of one or multiple layers of cement-based mortar reinforced with an open mesh of dry fibers (fabric). This thesis presents an experimental and analytical study which investigates the effectiveness of using FRCM composites to improve the out-of-plane resistance of URM walls when subjected to blast loading. As part of the experimental program, two large-scale URM masonry walls were constructed and strengthened with the 3-plies of unidirectional carbon FRCM retrofit. The specimens included one infill concrete masonry (CMU) wall, and one load-bearing stone wall. The University of Ottawa Shock Tube was used to test the walls under gradually increasing blast pressures until failure, and the results were compared to those of control (un-retrofitted) walls tested in previous research. Overall, the FRCM strengthening method was found to be a promising retrofit technique to increase the blast resistance of unreinforced masonry walls. In particular, the retrofit was effective in increasing the out-of-plane strength, stiffness and ultimate blast capacity of the walls, while delaying brittle failure and reducing fragmentation. As part of the analytical research, Single Degree of Freedom (SDOF) analysis was performed to predict the blast behaviour of the stone load-bearing retrofit wall. This was done by computing wall flexural strength using Plane Section Analysis, and developing an idealized resistance curve for use in the SDOF analysis. Overall, the dynamic analysis results were found to be in reasonable agreement with the experimental maximum displacements.

No description available.

No description available.