Browsing by Author "Jaimes, Miguel A."
Now showing 1 - 7 of 7
Results Per Page
Sort Options
Item A New State-of-the-Art Platform for Probabilistic and Deterministic Seismic Hazard Assessment(2019) Candia, Gabriel; Macedo, Jorge; Jaimes, Miguel A.; Magna-Verdugo, CarolinaA 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 performancebased 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.Item Cost-Benefit Analysis of Seismic Mitigation Measures for Wine Barrel Stacks(2017) Jaimes, Miguel A.; Candia, Gabriel; Favier, PhilomèneThis study conducts a cost-benefit analysis of alternative seismic risk mitigation methods for wine barrel stacks. The Chilean wine industry is presented as an illustrative case study, in which performance metrics such as the expected annual loss and benefit-cost ratios are computed for wineries at different locations. By computing seismic risk within a consistent framework, this study shows the value of cost-benefit simulations for defining the best mitigation strategies and allocating economic resources. Likewise, this approach helps to communicate information to decision-makers because it is presented in a simple and transparent way, even if they are not familiar with formal risk studies. For 3-level wine barrel stacks, it was observed that the Cradle Extender® (MS1) prevents a large number of barrel collapses and provides the highest benefit-cost ratio. On the other hand, for 6-level wine barrel stacks, the pre-stressed cable (MS2) is more effective than MS1 as it prevents the barrel stack from overturning. No significant reduction of loss is apparent in 4 and 5-level wine barrel stacks with the use of mitigation strategies; indeed the mitigation strategies could generate greater losses and, therefore, other alternatives must beItem Ground Motion Correlations from Recorded Mexican Intermediate-depth, Intraslab Earthquakes(2021) Jaimes, Miguel A.; Candia, Gabriel; López-Castañeda, Alhelí; Macedo, JorgePredictive models to estimate correlation coefficients between peak ground acceleration, peak ground velocity, and spectral acceleration residuals for Mexican intermediate-depth, intraslab earthquakes recorded on rock sites are presented in this study. The models were developed for the total, between-events, and within-event residuals using a recent ground-motion prediction equation (GMPE) and an updated ground-motion database. The results support the use of region- and mechanism-specific correlation models for the subduction intraslab zone of Mexico. An example of the application of the proposed correlation coefficient models consisting in evaluating a conditional mean spectrum (CMS), based on the Mexican seismic design normative, is presented.Item Interperiod correlation model for Mexican interface earthquakes(2019) Jaimes, Miguel A.; Candia, GabrielThis 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.Item Seismic risk of sliding ground-mounted rigid equipment(2020) Jaimes, Miguel A.; Candia, GabrielThis study discusses a general formulation for risk assessment of ground-mounted rigid sliding equipment and contents during earthquakes. The displacement and acceleration response of blocks during earthquakes and risk were examined for four types of support conditions: (1) equipment simply supported on a foundation; (2) equipment restrained to a fixed base; (3) equipment supported on a linear viscoelastic isolation system; and (4) equipment supported on a single concave spherical sliding (SCSS) isolation system. Because empirical fragility functions for sliding-dominated equipment remain insufficient, the present study relies on numerical analysis and a solid physical background to compute risk. These results should aid designers in the selection of appropriate support conditions or mitigation measures for rigid equipment and contents in seismic-prone regions. As an example, the seismic response of rigid equipment is illustrated using ground motions from the recent (2017) Mexico earthquakes, which damaged several pieces of equipment in the largest oil refinery in Mexico. Furthermore, the effects of site-to-source distance for sites located on firm soil are studied in detail, as the frequency content of these ground motions differ significantly and play a key role in the reliability of sliding blocks. The results of the seismic risk assessment show that low-frequency ground motions (i.e., far-field site) generally yield lower maximum and residual equipment displacements compared to those from high-frequency ground motions (i.e., near-source site). This investigation also concludes that the reliability of freestanding and base-isolated equipment in terms of maximum absolute block accelerations is higher than that of anchored equipment.Item Seismic Vulnerability of Wine Barrel Stacks(01/11/2016) Candia, Gabriel; Jaimes, Miguel A.; Arredondo, César; de la Llera, Juan Carlos; Favierc, PhilomèneRecent earthquakes have shown that wine barrel stacks are highly susceptible to collapse, leading to large economic losses, downtime, and longer recovery periods. This study presents a methodology using a probabilistic approach for estimating the fragility functions and economic losses in barrel stacks. The seismic response of these systems was determined from the dynamic equilibrium equations that describe the position and orientation of each element. The analysis considered ground motions scaled at different intensity levels and different barrel stack configurations; the simulations enabled reproducing the most common collapse mechanisms observed in the field and in shaking table experiments. From a statistical analysis of the results, vulnerability functions were evaluated as the probability of being within a specific damage state for a given ground motion intensity. Additional numerical simulations were performed to study the effects of the inherent uncertainty of the interface parameters controlling the dynamic response and collapse sequence of the barrel stacks. Furthermore, this methodology was used to evaluate the impact effect and improvement of a base isolation solution as a damage mitigation measureItem Toppling of Rigid Electric Equipment during Earthquakes(2018) Jaimes, Miguel A.; Candia, GabrielThis study presents a general formulation for toppling risk assessment of rigid electrical equipment during earthquakes. The seismic response, toppling fragility functions and toppling risk were examined for three types of support conditions, namely: 1) equipment simply supported on the foundation; 2) equipment anchored to the foundation; and 3) equipment supported on a seismic base isolator. Because empirical fragility functions for overturning equipment remain insufficient, the present study relies on numerical analysis and a solid physical background to compute risk. These results should aid designers in the selection of appropriate support conditions or mitigation measures for rigid electric equipment in seismic prone regions. As an example, the toppling risk methodology is presented using Mexican seismicity and a set of nine electrical equipment commonly used throughout Mexican power stations, with heights between 3 and 5 m, covering an ample range of frequency parameters (1.54 < p < 2.16 rad/s), and block dimensions (1.58 m < R < 2.49 m). Further, the effects of site-to-source distance for sites located on firm soil are studied in detail, as the frequency content of these ground motions differ significantly and play a key role in the toppling vulnerability of the blocks. The study shows that the reliability index increases monotonically with increasing block aspect ratio and block size for the nine equipment and the three support conditions studied. This investigation also demonstrates that the reliability of free-standing equipment due to near-source ground motions is slightly higher than that of anchored equipment or base isolated equipment. In contrast, for far-field ground motions, the reliability for anchored equipment is slightly higher than that of free- standing or base isolated equipment.