Browsing by Author "Crempien, J. G. F."

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    Performance of an RC building under seismic and tsunami actions in sequence via nonlinear dynamic analysis including soil-structure interaction
    (2022) Cortez, C.; Junemann, R.; Fernandez, C.; Urrutia, A.; Crempien, J. G. F.; Cienfuegos, R.
    This research presents a methodology to study the behavior of buildings subjected to seismic and tsunami loading in sequence, considering soil structure interaction effects through a complete dynamic analysis. The case-study building is an RC frame, which is assumed to be located in a coastal city in Chile, and built on sandy soil. A 3D Soil-Structure Interaction (SSI) model, including the non-linear behavior of both the structure and the soil using finite element method (FEM) was presented. Synthetic seismic ground motion records and tsunami inundation time histories were generated, consistent with the same earthquake source. Building performance was first assessed considering the SSI model for each hazard separately and compared to a Fixed Base (FB) model. Then, the SSI model was subjected to seismic and tsunami loading in sequence. Engineering Demand Parameters (EDPs) of roof displacement, interstory drift ratio (IDR) and reinforcement strain in beams and columns were analyzed. These EDPs presented a larger response to the tsunami when the response to the previous earthquake was larger. Finally, two vertical evacuation building scenarios were studied: the location of the refugees and the effect of an aftershock occurring simultaneously with the tsunami inundation. Results showed that the location of the ref-ugees did not generate significant differences in the building response, and the aftershock increased the response only when it coincided with the maximum tsunami force.
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    Plate-Locking, Uncertainty Estimation and Spatial Correlations Revealed With a Bayesian Model Selection Method: Application to the Central Chile Subduction Zone
    (2022) Becerra-Carreno, V; Crempien, J. G. F.; Benavente, R.; Moreno, M.
    Inversions of geodetic data are regularly used to estimate interseismic locking in subduction zones. However, the ill-posed nature of these problems motivates us to include prior information, physically consistent with processes of the subduction seismic cycle. To deal with model instabilities, we present an inversion method to estimate both plate-locking and model uncertainties by inverting Global Navigation Satellite System derived velocities based on a Bayesian model selection scheme. Our method allows us to impose positivity constraints via a multivariate folded-normal distribution, with a specified covariance matrix. Model spatial correlations are explored and ranked to find models that best explain the observed data and for a better understanding of locking models. This approach searches for hyperparameters of the prior joint multivariate probability density function (PDF) of model parameters that minimize the Akaike Bayesian Information Criterion (ABIC). To validate our approach, we invert synthetic displacements from analytic models, yielding satisfactory results. We then apply the method to estimate the plate-locking in Central Chile (28 degrees-39 degrees S) and its relation to the coseismic slip distribution of earthquakes with magnitudes M-w > 8.0, on the subduction zone since 2010. We also search among different prior PDFs for a single ductile-fragile limit depth. Our results confirms a spatial correlation between locked asperities and the 2010 M-w 8.8 Maule and 2015 M-w 8.3 Illapel earthquake rupture zones. The robustness of our locking model shows potential to improve future seismic and tsunami hazard estimations.