Now showing 1 - 10 of 14
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An integrated platform for seismic hazard evaluation

2018 , CANDIA AGUSTI, GABRIEL , MacEdo J. , Magna-Verdugo C.

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Performance-based assessment of the seismic pseudo-static coefficient used in slope stability analysis

2020 , Jorge Macedo , CANDIA AGUSTI, GABRIEL ALFONSO

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Interperiod Correlation Model for Mexican Interface Earthquakes

2019 , Miguel A. Jaimes , CANDIA AGUSTI, GABRIEL ALFONSO

This article presents a correlation model for pseudo-acceleration, peak ground acceleration, and peak ground velocity residuals using a database of Mexican subduction interface earthquakes at rock sites (NEHRP Class B). A mixed-effect regression model, a ground motion model, and 40 event recordings (418 records) with moment magnitude between five and eight were used to develop a magnitude-independent correlation model. This region-specific model yields consistently higher correlation values compared with similar studies developed for shallow crustal regions and other subduction zones worldwide, particularly for pseudo-acceleration values at distant periods. These results support the idea of using a region-specific and mechanism-specific correlation model for Mexico's subduction zone.

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Performance-based analysis of Transit tunnels in the Chilean subduction zone

2022 , Benjamín Lyon , CANDIA AGUSTI, GABRIEL ALFONSO , Carlos Gutiérrez , Jorge Macedo

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A simplified and versatile element model for elastomeric seismic isolation bearings

2021 , Sebastián Miranda , Eduardo Miranda , Juan Carlos de la Llera

A novel approach for two-dimensional modeling of elastomeric bearings using three springs in parallel is presented. This simplified element model considers as follows: (1) an elastoplastic spring with a smooth transition between branches; (2) a linear elastic spring; and (3) a non-linear elastic spring, and is fully defined by only six parameters. The main advantages of the simplified model are twofold: (1) versatility, as a single model is capable of accurately reproducing the main characteristics of the hysteretic behavior of different types of rubber-based seismic isolators, including low damping rubber bearings (LDRBs), high damping rubber bearings (HDRBs), and lead-core rubber bearings (LRBs) and (2) simplicity, as it requires fewer parameters and it is easier to calibrate from experimental cyclic test results than most currently available models. Model parameters’ identification is illustrated using quasi-static cyclic and earthquake simulator tests of HDRBs and LRBs, demonstrating that the model shows a good agreement between the test-measured and model-predicted hysteretic behavior. Different objective functions are evaluated in the optimization procedure, and their effect on the identified parameters is studied and discussed. This practitioner-oriented model is particularly amenable for implementation in general-purpose structural analysis software. Its usage is strongly recommended as an initial-stage design tool to select the optimal isolation system for a specific project.

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Uncertainty on measurement of elastomeric isolators effective properties

2021 , Sebastián Miranda , Juan Carlos de la Llera , Eduardo Miranda

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Correlations of spectral accelerations in the Chilean subduction zone

2020 , CANDIA AGUSTI, GABRIEL ALFONSO , Alan Poulos , Juan Carlos de la Llera , Jorge G.F. Crempien , Jorge Macedo

The correlation between spectral accelerations is key in the construction of conditional mean spectra, the computation of vector-valued seismic hazard, and the assessment of seismic risk of spatially distributed systems, among other applications. Spectral correlations are highly dependent on the earthquake database used, and thus, region-specific correlation models have been developed mainly for earthquakes in western United States, Europe, Middle East, and Japan. Correlation models based on global data sets for crustal and subduction zones have also become available, but there is no consensus about their applicability on a specific region. This study proposes a new correlation model for 5% damped spectral accelerations and peak ground velocity in the Chilean subduction zone. The correlations obtained were generally higher than those observed from shallow crustal earthquakes and subduction zones such as Japan and Taiwan. The study provides two illustrative applications of the correlation model: (1) computation of conditional spectra for a firm soil site located in Santiago, Chile and (2) computation of bivariate hazard for spectral accelerations at two structural periods.

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New developments for the performance-based assessment of seismically-induced slope displacements

2020 , Jorge Macedo , CANDIA AGUSTI, GABRIEL ALFONSO , Maxime Lacour , Chenying Liu

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A New State‐of‐the‐Art Platform for Probabilistic and Deterministic Seismic Hazard Assessment

2019 , CANDIA AGUSTI, GABRIEL ALFONSO , Jorge Macedo , Miguel A. Jaimes , Carolina Magna‐Verdugo

ABSTRACTA new computational platform for seismic hazard assessment is presented. The platform, named SeismicHazard, allows characterizing the intensity, uncertainty, and likelihood of ground motions from subduction‐zone (shallow interface and intraslab) and crustal‐zone earthquakes, considering site‐specific as well as regional‐based assessments. The platform is developed as an object‐oriented MATLAB graphical user interface, and it features several state‐of‐the‐art capabilities for probabilistic and deterministic (scenario‐based) seismic hazard assessment. The platform integrates the latest developments in performance‐based earthquake engineering for seismic hazard assessment, including seismic zonation models, ground‐motion models (GMMs), ground‐motion correlation structures, and the estimation of design spectra (uniform hazard spectra, classical conditional mean spectrum (CMS) for a unique tectonic setting). In addition to these standard capabilities, the platform supports advanced features, not commonly found in existing seismic hazard codes, such as (a) computation of source parameters from earthquake catalogs, (b) vector‐probabilistic seismic hazard assessment, (c) hazard evaluation based on conditional GMMs and user‐defined GMMs, (d) uncertainty treatment in the median ground motions through continuous GMM distributions, (e) regional shaking fields, and (f) estimation of CMS considering multiple GMMs and multiple tectonic settings. The results from the platform have been validated against accepted and well‐documented benchmark solutions.

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The effect of spectral shape on damping modification factors

2020 , Sebastián Ignacio Miranda , Eduardo Miranda , Juan Carlos de la Llera

The main objective of this study is to investigate the effect of spectral shape on damping modification factors η used in equivalent static and response spectrum analyses of structures with damping ratios that are different from 5% critical damping. Record-to-record variability of η is also evaluated through a statistical analysis of 5270 ground motions records from 1137 interface earthquakes recorded in Chile. The effect of spectral shape is studied using recently developed spectral shape metrics SaRatio and epsilon [Formula: see text] and evaluating their use as possible predictors for η. Similarly to previous investigations, this article also examines the effect of oscillator period, earthquake magnitude, and earthquake duration for different levels of damping ratio. Results suggest that SaRatio is an effective predictor of η, particularly for highly damped structures. However, results also indicate that for rock and firm sites, earthquake faulting mechanism and site class do not have a significant influence on η. A simple period-independent regression model for η as a function of SaRatio and damping ratio is proposed. A comparison between median η from this study and those in current Chilean seismic codes shows that code factors are unconservative.