Rivera Figueroa, Alan A.

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    Clasificación de suelos según el NEHRP para el municipio de Arecibo
    (2009-05) Rivera Figueroa, Alan A.; Ramos Cabeza, Ricardo; College of Engineering; Martínez Cruzado, José A.; Pando López, Miguel A.; Department of Civil Engineering; O’Hallorans Castillo, Julia M.
    Este proyecto es parte de un proyecto de investigación realizada para la oficina del Comisionado de Seguros de Puerto Rico. El proyecto consiste en la generación de mapas de tipos de suelo para el municipio de Arecibo. Las suelos se clasifican según el NEHRP (National Earthquake Hazards Reduction Program). El generar estas zonas envuelve la recopilación y organización de información sobre los suelos a ser estudiados. Para suelos tipo F, la evaluación se apoya en aplicar la metodología propuesta por Youd et al. (2002) combinado con el uso del índice potencial de licuación (Liquefaction Potential Index, LPI) propuesto por Iwasaki et al. (1982). Las herramientas utilizadas para la organización de la información y análisis de licuación son los programas LicuadoPR y ARCGIS 9.0. El mapa de clasificación de suelo tipo NEHRP generado incluye los suelos tipo F susceptibles a la licuación.
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    On the use of RotD100 spectrally matched records as seismic input for bidirectional nonlinear response history analyses
    (2022-12-12) Rivera Figueroa, Alan A.; Montejo Valencia, Luis A.; College of Engineering; Vidot Vega, Aidcer L.; Suárez, Luis E.; Ramos Cabeza, Ricardo; Department of Civil Engineering; Acuña Guzmán, Salvador F.
    Different methodologies for the generation of ground motion pairs compatible with a target RotD100 spectrum and their use as seismic input for bidirectional nonlinear response history analyses of civil structures are investigated. The methodologies studied include the traditional approach of separately matching of each horizontal component to the target RotD100, and a more recently proposed approach based on the simultaneous modification of both horizontal components to tightly match the target RotD100. Input sets were also generated using widely accepted amplitude-scaling approaches and are used as baseline for comparison of the results obtained from the spectral match strategies. Two types of structural systems were studied, idealized single-column pier bridges and multistory buildings comprised of space frames. The numerical models were developed in OpenSeesPy using a fiber-based approach that account for axial load – moment capacity interaction, second order (P-Delta) effects, and the strength and stiffness degradation due to increasing levels of lateral demand and low cycle fatigue. The strong motion characteristics of the developed ground motion pairs were examined individually and their spectral amplitude variability as suites of input records. It was found that the ground motion pairs generated by simultaneously modifying both horizontal components, attained the closest match to the target RotD100, retained better the strong motion characteristics of the seed records and their horizontal components exhibited a spectral variability comparable to the observed in suites of amplitude-scaled records. Conversely, matching separately each horizontal component generated records disproportionated intensities as measured by the Arias Intensity and the RotD100 spectral amplitudes, which greatly surpassed the target spectrum. The effect on seismic response was evaluated based on the predicted peak lateral drift and total rebar strain energy. The records generated by separate matching of the components caused unrealistic large inelastic demands when compared to the results expected from amplitude-scaled records. On the other hand, the sets generated by simultaneous modification of the horizontal components to directly match the target RotD100 imposed the mean peak drift and mean total energy demands closest to the imposed by the amplitude-scale sets, however, for some structures the mean peak drift demand was slightly but consistently below the expected from amplitude-scaled sets. This unconservative bias vanished when the same approach was implemented using 110% the target spectrum to comply with the ASCE7 minimum spectral amplitude requirement for spectrally matched records. Finally, the effect of rotating the horizontal components was also studied. It was found that the directionality in the structural response is dominated by the azimuth dependency of the structure lateral load resisting system. Results obtained for individual records show that rotating the horizontal components at different angles generated maximum peak drifts 30% larger, in average, than the average peak drift from all rotations studied. However, the directionality effect is reduced when considering mean results from sets of 11 records, the expected demand from a set with motions at a fixed rotation was ±10% the expected demand when rotations were included. No correlation was found between the response directionality and the level of inelastic lateral demand, the methodology used to generate the seismic input or the directionality in the input record.