Browsing by Author "Araya-Letelier, G."

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    (33, 33) Guzman, C.; Araya-Letelier, G.; Astroza, R.; Miranda, E.; Gallegos, M. F.; 33
    Extensive evidence indicates that steel-frame (SF) gypsum-board (GB) partitions are susceptible to seismic damage from very small story drift ratio (SDR) demands, which can lead to significant economic losses, environmental impacts, and downtime in buildings. To mitigate this risk, several innovations have been developed in SF-GB partitions, among which the use of adhesive connections (ACs) recently stands out as a replacement strategy to screw connections (SCs) for attaching GBs to SFs. The use of ACs has shown significant increments in both strength and stiffness of partitions, compared to partitions with SCs. However, the behavior of ACs has been studied mainly under in-plane loads and without a detailed analysis of the use of ACs in the reduction of damage states (DSs) neither the generation of fragility curves. This research presents an experimental study of 36 full-scale SF-GB panels, where the structural behavior under out-of-plane loads of SC-SF-GB and AC-SF-GB panels, as well as other design variables such as GB thickness and type of SF, are assessed and compared in terms of strength, stiffness, and DS evolution. The results of the test campaign show that the mean strength and stiffness of AC-SF-GB panels are 101 % and 47 % higher than those of the SC-SF-GB panels, respectively. In addition, AC-SF-GB panels exhibit a better performance compared to SC-SF-GB panels in terms of DS evolution. The results indicate that the type of connection is a design variable with significant impact on the strength, stiffness, and damage evolution of partitions, over the GB thickness and the type of SF. Finally, the developed fragility functions, which pass the goodness-of-fit tests, confirm the enhanced seismic performance of the AC-GB-SF panels and are a key component to perform future loss estimation studies for building-specific assessments.
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    (33, 33) Burbano-Garcia, C.; Araya-Letelier, G.; Astroza, R.; Silva, Y. F.; 33
    This study assesses the feasibility of the incorporation of fibrillated polypropylene fibers (FPFs), an engineered multidimensional and multifilament fiber mostly used to reinforce concrete mixtures, into adobe mixtures (AMs), a traditional and manually-made material used to produce adobe blocks. The incorporation of FPFs was assessed using increasing dosages (0%, 0.25%, 0.5%, and 1% in wt% of clay soil) of FPFs. These fibers were gradually added and mixed with the clayey soil prior to incorporation of water to promote uniform mixtures with adequate fiber distribution to reduce the formation of fiber clusters. The impact of FPFs was evaluated in terms of its effects on the bulk density (physical), compressive and flexural strength (mechanical), flexural toughness indices (fracture) and water erosion resistance (durability) of AMs. Results indicate that increasing dosages of FPFs monotonically reduce average values of bulk density, as well as compressive and flexural strength of AMs. On the other hand, these increasing dosages of FPFs monotonically increase average values of water erosion resistance as well as flexural toughness indices, varying the flexural failure mode from brittle (unreinforced AM) to ductile (reinforced AMs) because of the adequate bonding and FPF-bridging effect after the crack generation as confirmed by instrumentation as well as digital image correlation evaluations implemented in this study. The significant reductions of bulk densities and compressive and flexural strengths obtained for fiber-reinforced AMs were related to the increasing number of fiber clusters found for increasing dosages of FPFs within the fiber-reinforced mixtures, which was evaluated using scanning electron microscopy analyses. For example, positively the AM incorporating 1% of FPFs increased, on average, the flexural toughness by 674% and reduced the bulk density and water erosion depth by, on average, 9% and 64%, respectively, when compared to the unreinforced AM. However, this large dosage of FPFs also generated a significant reduction of the compressive strength (60% on average) and the flexural strength (43% on average) when compared to the plain mixture. On the other hand, a small dosage of FPFs (0.25%) generated less significant improvements in terms of flexural toughness, bulk density, and water erosion (on average, increment of 58% and reductions of 2% and of 38%, respectively, when compared to the unreinforced AM). Yet, the latter mixture presented reductions, on average, of compressive and flexural strengths of 24% and 16%, respectively, when compared to the plain mixture, and these reductions were significantly smaller than the reductions obtained by the largest FPF dosage, due to the significantly smaller number of fiber clusters presented by the 0.25% dosage when compared to the 1% dosage. Finally, the mechanical performance limitations exhibited by the incorporation of FPFs, especially in large dosages, are related to generated fiber clusters due to the inherent morphology of these FPFs as well as the traditional manual confection process of AMs. Therefore, this study recommends the implementation of FPFs in AMs, but in small dosages and/or suggests the implementation of a mechanical mixing/compaction process that guarantee a more uniform fiber distribution that reduces the generation of fiber clusters.