Browsing by Author "Contreras, Nicolás"

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    33
    (33, 33) Hernández Prado, Francisco Javier; Contreras, Nicolás; Zhang, Xihong; Hao, Hong; 33
    Interlocking bricks have emerged as a promising alternative to traditional masonry, primarily due to their self-aligning capabilities, which accelerate construction and reduce dependency on skilled labour—advantages particularly valuable for addressing Australia's labour shortages and high costs. However, dry-stacked interlocking brick assemblies inherently exhibit gaps between bricks arising from surface roughness and dimensional variations. Extensive research has shown that these gaps induce stress concentrations and initial non-linear behaviour under static compressive and shear loading while enhancing energy absorption and dissipation under dynamic loading. Despite their known influence on dynamic performance parameters, the impacts of inter-brick gaps on the dynamic response of dry-stacked interlocking bricks during impact loading remain unknown. This study characterises the dynamic response through a combination of experimental testing, analytical simplifications, and stochastic analysis of interlocking brick assemblies. Instrumented impact hammer tests conducted on interlocking assemblies revealed that the inherent gaps cause pounding between adjacent bricks, resulting in high-frequency dynamic responses. An analytical approach was developed to characterise the inter-brick pounding, with results indicating that the timing of pounding events primarily influences the dominant frequency of the assembly. A stochastic method was employed to directly assess the influence of inter-brick gaps on the Fourier spectrum and to establish the boundaries of the analytical analysis. Furthermore, a novel design integrating meta-concrete with interlocking bricks is proposed to exploit these high-frequency responses beneficially. Numerical simulations demonstrated that meta-concrete interlocking brick systems attenuated acceleration responses induced by impact forces by up to 26 %, highlighting the synergy between these technologies for potential applications.
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    (33, 33) Arellano, Benjamín; Hernández, Francisco; Massone, Leonardo M.; Astroza, Rodrigo; Soto, Pedro; Contreras, Nicolás; Garrido, Bastián; 33
    A novel system identification technique called Mod-? (var) is formulated, implemented, and validated to study the seismic response of a 3D R/C shear wall building during the 2010 central Chilean mega-earthquake (Mw = 8.8). The Mod-?(var) approach is an evolution of Least-Square modal system identification techniques, where modal parameters are adjusted through small data windows to fit seismic data in the frequency and time domains. This technique offers several advantages over traditional methods, including the estimation of time-variant dynamic properties during seismic events and the reliable assessment of continuous nonlinear modal responses. As a result, the Mod-?(var) approach allows for determining empirical response spectra related to each seismic input. The technique can also compute the local response of measured and unmeasured floors as the product between the nonlinear modal responses (obtained from the Mod-?(var) approach) and the normalized seismic mode shapes for all building floors, which can be estimated from ambient vibration data. Finally, the seismic floor deformations can be imposed on a FEM to determine relevant engineering quantities such as inter-story drift, inter-story forces, and local demand of structural elements (e.g., drift ratios, curvatures, internal forces, stresses, strains, etc.).
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    Application of elastic metamaterials/meta-structures in civil engineering: a review
    Contreras, Nicolás; Zhang, Xihong; Hao, Hong; Hernández, Francisco