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Urban areas located on complex geological formations, such as dune deposits, require detailed seismic risk assessments that extend beyond standard seismic codes. This study focuses on the city of Concón, Chile, where a significant portion of the urban area is situated on a coastal dune deposit. The research integrates seismic microzonation with a three-dimensional finite element model (3D FEM) to comprehensively evaluate the regional seismic response. Field data from 208 strategically distributed points were collected and combined with geotechnical and geomorphological information to construct a detailed 3D model of the region. This model allowed for the simulation of seismic behavior under various conditions, highlighting the limitations of general seismic codes in capturing local variations in seismic response. The results underscore the importance of considering local geological conditions in structural design, particularly in areas with irregular topography and complex subsurface conditions. This study concludes that incorporating microzonation into urban planning and seismic analysis can significantly enhance infrastructure resilience and disaster preparedness, providing a replicable approach for other cities facing similar geological challenges.

The fundamental period of a terrain is a key parameter for characterizing the maximum soil amplification. Since the 1960s, research has been conducted for sloping terrains with a focus on evaluating topographic effects. However, few studies have focused on identifying whether the site topography induces an amplification peak that is associated with a characteristic period of sloping terrain. This study conducts a parametric analysis to identify a potential amplification pattern attributable to terrain geometry, using two-dimensional finite element models subjected to the action of a dynamic signal. The periods in which amplification peaks are generated are evaluated and compared with the amplification response recorded in the free field on horizontal terrain. The results reveal that the dynamic response of sloping terrain is a combination of the response from the surrounding terrain to the sloping zone and vice versa, and a distinctive amplification peak linked to the topography is identified. A new expression is proposed to define a topographic seismic site period in terms of shear wave velocity and the total soil thickness from the bedrock to the crest of sloping terrain. This study advances the processes of characterizing the seismic response of sloping terrains by demonstrating that the topographic seismic site period is consistent regardless of the slope angle. This provides engineers with a new dimension of analysis for the practical definition of criteria to determine topographic effects in design spectra.

Esta Corrección es para aclarar y sustituir las diferencias en el artículo del Volumen 23, Número 2, julio-diciembre, p. 107-122, Gaceta Técnica, entre lo publicado y lo que posteriormente envía el autor como aclaratorias a fin de que se proceda a publicar como enmienda. El Comité editorial no es responsable de estas diferencias

La gran mayoría de los estudios sobre análisis de la capacidad de soporte de cimentaciones, tienen como base el trabajo de 1920 del profesor Ludwig Prandtl titulado “Über die härte plastischer körper” (Sobre la dureza de los cuerpos plásticos). Sin embargo, no es común encontrar referencias que presenten las diferentes consideraciones que hay detrás de la propuesta original. Como, por ejemplo, que el método exhibido es de origen teórico, sin validación empírica, no siendo formulado ni para suelos, ni para cimentaciones, ya que tenía como objetivo evaluar la dureza de un material sólido, mediante la determinación del esfuerzo que produce su plastificación total. Considerando lo anterior, se presenta una versión rigurosa del artículo original completo de Prandtl de 1920, adaptado del alemán al español, con lo cual se espera contribuir en el conocimiento sobre los principios, consideraciones y límites de validez, de la ampliamente conocida Cuña de Prandtl, la cual representa uno de los pilares de los métodos para el diseño geotécnico de cimentaciones superficiales.

El diseño de cimentaciones superficiales es quizás uno de los requerimientos más habituales en la práctica profesional en ingeniería geotécnica, lo que ha motivado el desarrollo de un importante número de investigaciones de tipo experimental, teórico y numérico, hasta la fecha. Los estudios sobre la respuesta de una cimentación superficial, inician con la propuesta del mecanismo de falla definido por Prandtl, y usado por Reissner en los años veinte del siglo XX, seguido de la formulación de la conocida ecuación polinómica de capacidad de soporte de Terzaghi en 1943. Basados en lo anterior, trabajos de pioneros en esta línea como Meyerhof, Skempton, Vesic y Brinch Hansen, por resaltar sólo algunos, han mantenido su vigencia a la fecha a nivel académico y profesional, debido a la naturaleza práctica de sus propuestas. Sin embargo, las metodologías derivadas de ellas, consideran indirectamente que la planta de cimentación está compuesta por elementos aislados, cuyo comportamiento es evaluado independiente de la estructuración y distribución de las cargas en la cimentación, lo que puede estar alejado de las solicitaciones que se tienen en un proyecto

Abstract In professional activities aimed at seismic site classification, geophysical methods based on measurements of surface waves are often used to measure the shear-wave velocity (Vs), with the MASW survey being one of the most common techniques employed for this purpose. An MASW survey is characterized by an in-field configuration that requires a relatively simple setup; however, several uncertainties that arise are related to the survey execution process. Thus, surface irregularities and/or obstacles on the ground surface in conjunction with possible human-related errors can result in alterations to the MASW survey execution. Therefore, it is necessary to possess a clear understanding of the variables that can potentially produce alterations in Vs profiles. The purpose of this study was to evaluate, based on a field measurement campaign, the effect of the repeatability of the sledgehammer trajectory prior to striking the plate and the effects of variations in the collinearity of the geophone arrays on the Vs profile in consideration of various forced alterations commonly encountered in practice. The repeatability of the active source trajectory plays a significant role in the quality and reliability of Vs measurements. Likewise, altering the collinearity of the geophone array leads to reductions in the amplitude at low frequencies, thereby hindering the interpretation of the test. The recorded effects become more relevant depending on the local conditions and whether the surveyed terrain exhibits possible heterogeneity.

Design codes establish seismic site classifications to determine the seismic demand of a structure according to the response of the soil foundation under the action of earthquake ground motions; the site classification can even condition the feasibility of a project. The occurrence of great earthquakes in Chile has tested its design codes, generating much information and experience regarding the seismic design of structures that have allowed researchers to identify variations in seismic demands according to the kind of ground foundation and to propose seismic site classification methods in Chilean regulations since the 1930s; countries in the vanguard of seismic design, such as the USA, Japan, and New Zealand, proposed methods even earlier. In this document, the evolution of methodologies for seismic site classification according to the criteria in Chilean codes is analysed from their implementation in the 1930s to the most recently proposed design code NCh 433, 2018–2021. Although the distinctive features of each country shape the criteria in their design codes, clear knowledge of the evolution of established criteria from their origins is considered an important tool that contributes to the better understanding, interpretation and application of the seismic site classification methodologies contained in a design code with better criteria. Likewise, the review indicates a distinct need to conduct a continuous evaluation of the classification criteria supported by records of new earthquakes, as well as by physical and numerical models that allow incorporating variables which condition the response of the terrain such as topography, lateral heterogeneities, and basic effects.