Browsing by Author "Escribano, Daniella"

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    Analysis of wood fly ash as sustainable alternative to cement replacement on concrete
    (2024) Ewert, Harold; Guinez, Felipe; Escribano, Daniella; Pradena-Miquel, Mauricio
    Supplementary cementitious materials (SCM) can contribute to reducing the carbon footprint of concrete. One of this SCM is the biomass fly ash (BFA) which is a waste of the wood production. Although different researchers have used BFA as SCM it is fundamental to know the concrete behaviour with local materials (including the available BFAs) to reduce the environmental impact of transportation. In particular, the Biobio region produces 57% of the Chilean wood, concentrated in Eucalyptus Globulus (E) and Pine Radiate (P) production. This paper describes the behaviour of concrete mixtures with replacements of BFAE or BFAP in 0%, 10% and 20% by weight of cement. Workability, compressive and flexural tests were performed, and the specimens were examined by scanning electronic microscopic (SEM) as well. The results show that BFAE reduced slump of fresh concrete and BFAP increased it on all cases due to their morphology. An increase in resistance at later ages is evident due to the increase in pozzolanic activity and BFAs morphology. The results indicate that BFAE and BFAP are suitable to replace at least 10% of cement, because those mixes present similar, and even higher, compressive and flexural strength than the control mix.
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    Two-dimensional nonlinear dynamic analysis of a liquefaction case history considering spatial variability and long-duration megathrust earthquakes
    (2024) Saldana-Sotelo, Hector; Montalva, Gonzalo; Escribano, Daniella; Nunez-Jara, Sebastian; Tiznado, Juan Carlos
    We analyzed the unusual liquefaction response of the Los Presidentes site in Concepci ' on, Chile, during the 2010 Mw 8.8 Maule earthquake, using a series of twodimensional nonlinear dynamic analyses (NDAs) on a well characterized subsurface. This site, characterized by interbedded clean and silty sands followed by a dense sand unit, included four identical towers that experienced different settlements, with maximum values reaching 40 cm for the most damaged tower to zero for the less affected one. We used SPT, CPTu, and Vs tests to characterize the soil's spatial variability. The NDAs used the PM4Sand and PM4Silt soil constitutive models implemented in OpenSees. The results suggest that the shear-induced deformation mechanism controls the dynamic response. The computed settlements matched post-earthquake LiDAR and field measurements, while liquefaction vulnerability indexes underestimated observed manifestations. Our results show that liquefactioninduced settlements due to megathrust earthquakes greatly differ from those induced by crustal ground motions.