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Item type:Publication, Damping modification factors for the design of seismic isolation systems in Peru(SAGE Publishing, 2020-11-01)This study proposed a simple nonlinear equation to estimate damping modification factors (DMFs) to modify the elastic response spectral values for damping ratios between 10% and 50%. The DMFs are computed from the displacement, acceleration, and velocity response spectral of single-degree-of-freedom (SDOF) systems of 198 earthquake acceleration time histories from 40 earthquakes events of Peruvian database, grouped into three types of soil: hard soil, intermediate soil, and soft soil. For each soil group, 11 scaled records were selected according to the ASCE 7-16 standard to match the design spectrum of the Peruvian technical standard for seismically isolated structures E.031. Simplified approximate nonlinear period-dependent expressions were provided to compute DMFs from the Peruvian strong-motion database and were compared with DMFs available in the literature and national seismic design codes. The study showed discrepancies with the regulations worldwide. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Uso de anclajes FRP en vigas de concreto armado reforzados externamente con bandas CFRP sometidas a cargas cíclicas(University of Costa Rica, 2020-05-28)En Perú existe una demanda creciente de mejorar, ampliar o remodelar la infraestructura existente, que generalmente ha sido diseñada con estándares estructurales menos exigentes que los actuales. Es por esta razón que se utilizan diversas técnicas entre las que se destaca el reforzamiento mediante sistemas FRP (fiber reinforced polymer). Entre las aplicaciones predominantes de este sistema se tiene el refuerzo a flexión de elementos de concreto armado (CA) tales como muros, losas y en especial las vigas. Durante la aplicación del FRP se pueden presentar diversas interferencias o limitaciones constructivas, lo que ha dado lugar al planteamiento de soluciones prácticas y modernas como el uso de sistemas de bandas de FRP, platinas y barras de FRP, sistemas FRP del tipo NSM, y el uso de anclajes de FRP. Estos procedimientos están contemplados en la guía ACI 440.2R (ACI, 2017), utilizada para la construcción y el diseño de refuerzo externo con FRP. El presente artículo muestra los resultados sobre la experiencia en laboratorio de cuatro vigas de CA, considerando que solamente tres fueron externamente reforzadas a flexión, además incluye el uso de anclajes hechos de FRP, para desarrollar el comportamiento a tracción de la banda FRP de refuerzo externo. Los especímenes se sometieron a cargas cíclicas mediante un ensayo cuasi-estático. Los resultados indican que estos elementos, reforzados con bandas y anclajes FRP, poseen una capacidad de resistencia superior a la capacidad nominal a flexión. Además, el comportamiento exhibido durante el ensayo fue estable y sin anomalías inesperadas que se hayan observado. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Parametric evaluation of the response modification factor R considering bidirectional ground motions(Elsevier Ltd, 2024-11-01)The current research on evaluating the response modification factor R, related to the lateral strength demand of structures, has been generally based on inelastic single-degree-of-freedom systems. Nevertheless, most structures have more than one main analysis component and will be subjected to bidirectional ground motions. In this study, the results of the parametric evaluation of the response modification factor considering the bidirectional interaction (Rb) of inelastic two-degree-of-freedom systems (2DOF) are presented. The effects on the factor Rb of the vibration period, the ductility capacity, the hysteretic model, the seismic incidence angle, and the period ratio were evaluated. Analysis results show that the bidirectional interaction could increase the lateral strength demand of the 2DOF systems because of the coupling effect of the two components’ responses. To make this research useful for improving engineering practice and code provisions, the main contribution is the proposal of a simplified expression for estimating the factor Rb. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Respuesta sísmica de edificios de 8 niveles de concreto armado con irregularidad en planta(University of Costa Rica, 2024-04-30)Para el modelamiento de estructuras, la hipótesis de diafragma rígido (DR) es empleada frecuentemente en el diseño sismorresistente, sin considerar si dicha hipótesis refleja una respuesta real de la edificación ante cargas de sismo. Desde una concepción arquitectónica, las edificaciones con tipologías de plantas irregulares satisfacen necesidades espaciales, funcionales y bioclimáticas; sin embargo, dichas estructuras se contraponen con su desempeño sísmico por tener respuestas diferentes. Además, se debe asumir una hipótesis para la losa de entrepiso que puede ser diafragma rígido (DR) o diafragma flexible (DF). Por lo tanto, es necesario conocer las respuestas lineales de estructuras con plantas irregulares. El objetivo del presente estudio es evaluar las configuraciones irregulares en plantas tipo L, H, T y U sobre el comportamiento sísmico de estructuras de ocho niveles, considerando las hipótesis de DR y DF. A partir de las respuestas globales y locales, se determinó que los casos de estudio con DF presentaron periodos de vibración más largos, que generaron mayores deflexiones de las estructuras, provocados por la deformación de la losa en su plano. Sin embargo, los valores de las fuerzas cortantes con DF fueron menores en comparación con los modelos con DR, debido a que la losa de entrepiso se deformó en su plano, lo que repercutió en la disminución del coeficiente de amplificación sísmica (C). Así, también, las tipologías L, T y U presentaron mayores demandas sísmicas, desplazamientos laterales y aceleraciones en los bordes en comparación al modelo H, que presentó desplazamientos laterales menores y uniformes. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Comportamiento sísmico de edificios irregulares en planta considerando sistemas de aislación con excentricidad de rigidez(University of Costa Rica, 2024-03-15)El objetivo de la presente investigación es evaluar el efecto de los parámetros dinámicos del sistema de aislación (el grado de acoplamiento torsional [Wb], el periodo de vibración [Tb], la razón de amortiguamiento crítico [xb] y la excentricidad de rigidez de la base de aislación [erb]) en el comportamiento torsional de una familia de edificios con seis pisos y aislados en la base de concreto armado, considerando las excentricidades de rigidez o masa (er o em, respectivamente) en la superestructura. Estas modifican su comportamiento estructural ante sismos severos e incrementan los desplazamientos laterales y las derivas de manera significativa. Para ello, se realizó un análisis no lineal tiempo-historia a cada modelo estructural, por lo que estos se sometieron a un conjunto de siete registros de aceleraciones sísmicas, medidos en la costa de Perú y Chile, los cuales fueron escalados según el espectro de diseño de pseudoaceleraciones vigente en Perú. Como respuestas globales de interés, se consideran los desplazamientos laterales máximos y las derivas de entrepiso. Así pues, se observó que el efecto de em generó mayores amplificaciones en los desplazamientos laterales y derivas que er. Similarmente, el parámetro erb fue muy influyente en el comportamiento torsional de los edificios aislados con em y er, pues amplificó los desplazamientos laterales hasta en un 50 %. Además, el parámetro Tb impactó notablemente las derivas de entrepiso, ya que las redujo hasta en un 55 %. Por otro lado, los parámetros Wb y xb fueron poco influyentes en dichas respuestas. - Some of the metrics are blocked by yourconsent settings
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Item type:Publication, Displacement-Based Seismic Performance of RC Bridge Pier(Springer, 2023-12-01)To correctly manage the road infrastructure before and after an earthquake, it is necessary to estimate and even predict the seismic performance of the bridge. The quantification of the bridge's seismic performance response was present in terms of displacement and also based on previous research of reinforced concrete bridge pier models. The displacement did define from a force lateral-displacement response diagram corresponding to the capacity curve, calculated through a non-linear static pushover analysis of the reinforced concrete bridge pier model for each limit state, from intact state to collapse. Thus, six defined displacements correspond to the cracking displacement, the yielding displacement, the spalling displacement, the crushing displacement, the buckling displacement, and the fracturing displacement. The six defined limit states correspond to the cracking limit state, the yielding limit state, the spalling limit state, the crushing limit state, the buckling limit state, and the fracturing limit state. Also, parametric analysis did carry out to evaluate the influence, relative importance, and trend of the input parameters in response to the seismic performance of the reinforced concrete bridge pier model. Eleven input parameters did analyze as the concrete compressive strength, the yield stress of reinforcing steel, the concrete cover thickness, the pier aspect ratio, the configuration of the transverse reinforcement, the spacing of the transverse reinforcing steel, the transversal diameter of the transverse reinforcing steel, the longitudinal reinforcement ratio, the transversal diameter of the longitudinal reinforcing steel, the axial load ratio, and coefficient of subgrade reaction. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Scale Factor Model to Estimate the Maximum Bidirectional Spectral Demand in the South American Region(Wiley, 2025-09-01)The intensity of seismic motion varies considerably with changes in direction, which is commonly known as the directionality of ground motion (GM). Different seismic design codes have adopted various methods for combining the intensity of horizontal GMs. These methods typically use the median spectral ordinate over all non‐redundant orientations, referred to as RotD50, and the maximum spectral ordinate over all non‐redundant orientations, referred to as RotD100. More recently, an intensity measure called MaxRotD50 has also been proposed and considered, which is calculated as the 50th percentile of the maximum spectral ordinates from two orthogonal horizontal directions for all non‐redundant rotation angles. This measure, which always lies between RotD50 and RotD100, offers several advantages over other intensity measures. In contrast to the approach in ASCE 7 (2010, 2022), which uses RotD100 for the design of all structures, this study proposes to use RotD100 only for the design of axisymmetric structures, that is, structures with vertical cylindrical symmetry and similar properties in terms of mass, lateral stiffness and strength. It is also proposed to use MaxRotD50 for the design of structures where the probability of exceeding the intensity of GM in at least one of the two horizontal principal components is high. Likewise, this study complements and compares the RotD100/RotD50 and MaxRotD50/RotD50 ratios, which can be used as a multiplicative factor with the RotD50 predictions to predict the RotD100 or MaxRotD50 of the GM intensity. A database of 3853 seismic acceleration records from 283 events in the South American subduction region is used for this purpose. The influence of GM parameters such as moment magnitude, significant duration, rupture distance, and mean soil period, was evaluated. The results were compared with those of previous studies for different regions of the world. It was found that the RotD100/RotD50 ratios in South America are like those in other subduction regions such as Taiwan and Japan and that the Max RotD50/RotD50 ratios are comparable to other shallow crustal earthquakes in active tectonic regions. Finally, equations are also proposed to estimate ratios depending on the different parameters of the evaluated GM to account for the found influence on the ratios.3 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Numerical study on frequency limit states in seismic performance of RC bridge pier(Springer Nature, 2026-12-01)This study presents a numerical investigation of the natural frequency of Reinforced Concrete (RC) bridge piers, which progressively decreases as seismic damage develops. The objective was to evaluate whether variations in natural frequency can reliably identify post-seismic damage states. To this end, a numerical RC bridge pier model was developed to quantify the evolution of its natural frequency across different stages of seismic performance, considering the full range of collapse mechanisms from undamaged to severely damaged conditions. Two post-seismic indicators, such as the Frequency Reduction Coefficient and the Frequency Decay Index, were defined to characterize changes in the natural frequency of bridge piers. Based on these indicators, six progressive frequency limit states were systematically established: Cracking, Yielding, Spalling, Crushing, Buckling, and Fracturing, providing a logical framework for post-seismic structural evaluation. A backbone curve of the numerical RC bridge pier was developed to assess stiffness degradation and the evolution of natural frequency during damage progression. In addition, an extensive literature synthesis was conducted to compile an experimental database to develop a baseline RC bridge pier model for comparative analysis. Results show that the natural frequency declines consistently with increasing damage, decreasing by approximately 30% from the elastic condition to the cracking stage and by nearly 70% at the fracturing stage, corresponding to overall structural collapse. The findings confirm that natural frequency thresholds can provide a systematic framework for assessing the condition of RC bridge piers after severe earthquakes. A key contribution of this study is the proposal of initial natural frequency thresholds associated with different damage levels, offering practical guidelines for bridge structural engineers. Furthermore, the compiled tables integrate experimental and numerical frequency data from multiple studies, forming a valuable reference dataset for future research on frequency-based seismic damage assessment.1