| Résumé | As part of a major rehabilitation project on the Centre Block of Parliamentary Buildings of Canada, an experimental investigation of the seismic behaviour of its existing terra cotta flat arch diaphragms is performed at the National Research Council Canada (NRC). Terra cotta flat arch diaphragms are a brittle floor system used in North America in the early 1900s. This system has demonstrated adequate behaviour to gravity loads as well as providing fire separation; however, its response to seismic loads has not been well assessed. An experimental program was needed to obtain data that will support the consulting design team in assessing the existing seismic performance of the floor diaphragms, as well as selecting appropriate retrofitting strategies for rehabilitating to meet the design objectives in mitigating seismic hazards. The overall testing program included obtaining samples of existing 100-year-old terra cotta tiles and determining material properties and exact physical dimensions of tiles. This information was needed to replicate existing tiles to be used in full-scale samples. To study the seismic performance of existing terra cotta flat arch diaphragms, several tests were performed on tiles, mortar mixes, tiles assemblies, and full-scale single-panel and multi-panel frames infilled with terra cotta tiles. Several single-panel and multi-panel samples were tested with different length-to-width ratios to resemble different on-site conditions. The single-panel frames were loaded diagonally under quasi-static loads, while the multi-panel frames are loaded laterally under cyclic loading. In this paper, the experimental results from the testing of multi-panel frames are presented. The load-displacement responses obtained from the testing can be used as input parameters by the consulting design team for the analysis and design of retrofitting alternatives for the floor system. Three multi-panel frames are tested with overall dimensions of approximately 4.5 m × 4.5 m. Testing is conducted to establish the capacity and behaviour of sliding shear within the terra cotta arches. The testing of multi-panel frames including peak and post-peak states of the frames, load-displacement response, and the sliding shear capacity are discussed. |
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