<p>The existing gap between minimum reinforcing requirements specified in the current Canadian masonry design standard (CSA S304.1 2004) and the provision for unreinforced masonry limits engineers to use the same minimum requirements for regions with low or moderate seismic demands. As a result, this restricts the use of reinforced masonry construction as a cost-efficient building system in regions with moderate seismic risks. In this research program, the performance of partially grouted reinforced masonry (PG-RM) shear walls, having larger reinforcement spacing than specified as minimum seismic requirements, has been evaluated to help in future efforts to offer some relief from the code's limitation.</p> <p>As the first phase of this research study, a computationally efficient numerical tool (finite element model) capable of predicting the pre- and post-peak response of PG-RM shear walls under in-plane loading was developed. The performance of the numerical model was evaluated by simulating available shear wall tests from other studies as well as the shear wall tests done as part of experimental program of this work. In general, acceptable accuracy was observed in numerically predicting both the pre- and post-peak behaviour of the shear wall specimens and the model was shown to be a reliable tool for further studies.</p> <p>The experimental program was intended to document the effects of reinforcement spacing and aspect ratio on the response of PG-RM shear wall under cyclic reversed loading. Direct small scale modelling using half-scale model concrete masonry units was chosen for the experiments. Two stages of testing were conducted. The first stage was designed to investigate the performance of masonry wallettes (panels) under the action of diagonal compression loading. Various patterns of grouting and reinforcing were studied by testing nine diagonal compression specimens. The second stage of the experimental research focused on the response of PG-RM shear walls under constant axial load and fully reversed cyclic lateral loading. The test matrix consisted of five masonry shear walls with nearly the same reinforcement ratios. The walls included three aspect ratios and three reinforcement spacings. Visual observations, loading, displacements, and crack pattern were recorded throughout the tests.</p> <p>The developed numerical model was used to expand the scope of the study to include the effects of level of axial load and amounts of horizontal and vertical reinforcement on the behaviour of PG-RM shear walls. In addition, the effect of reinforcing two cells at the ends of a PG-RM shear wall was also simulated. Close agreement was observed between the shear resistance estimated based on the Canadian masonry design standard (CSA 2004) and the experimental results of the PG-RM shear walls dominated by the shear failure mode. However, it was shown that the seismic load reduction factor, R value, suggested by CSA (2004) underestimates the energy dissipation ability of PG-RM shear walls despite the shear dominated behaviour observed for the test walls.</p> <p>The finding of this research study indicates a relatively ductile behaviour with satisfactory energy dissipation capability for PG-RM shear walls. This emphasises potential application of this type of wall as a more cost-efficient alternative in the future of masonry construction.</p> / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/13702 |
| Date | January 2008 |
| Creators | Maleki, Majid |
| Contributors | Drysdale, R. G., Civil Engineering |
| Source Sets | McMaster University |
| Detected Language | English |
| Type | thesis |
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