Abstract Nowadays, despite the implementation of new wind farms in Brazil, it still is difficult to form partnerships with companies in the sector, which significantly contributes to the gap in information provided by national literature and the lack of knowledge about the mechanical behavior of wind turbines subjected to transient wind effects. Therefore, through a Research and Development Project to optimize and improve modeling in wind systems, the Brazilian electric power company Eletrobras Furnas aims to facilitate the construction of smaller wind turbines to supply energy to regions far from the Brazilian coast that do not have high generation potential due to the incidence of low-speed winds. Two relevant aspects directly linked to the performance of this kind of structures are: (i) determining their natural frequency and (ii) ensuring that this frequency does not coincide with any external vibration frequency that the structure may experience in its lifetime. Wind turbines are complex systems with many degrees of freedom and their own frequencies associated with the respective mode shapes in which they naturally vibrate. These frequencies are inversely related to the mass and directly related to the stiffness of the structure. Thus, through numerical modeling using the Finite Element Method, the present article aims to list some of the main factors that can affect the prediction of the natural frequency of a real-scale wind turbine prototype and to evaluate its dynamic behavior, considering its rotor revolution frequency, its blade passing frequency and the wind characteristics of its operating area. Nowadays Brazil sector effects Therefore lowspeed low speed winds i (i ii (ii lifetime vibrate Thus Method realscale real scale area

Abstract This paper focuses on the use of the agglomerate technique to simulate crushable particles in the Discrete Element Method. A novel approach is proposed to design a Weibullian agglomerate by mimicking flaws within the crushable particle. The particle is designed with a constant number of sub-spheres in contrast to the approach widely used in the literature. However, the adhesion bonds between sub-spheres within the particle are selected randomly from a normal distribution. The normal distribution is designed to generate negative adhesion values, which are replaced by zero adhesion to mimic flaws within the particle. It is shown that the particle designed in this fashion exhibits a tensile strength that follows the Weibull probability function. This includes the effect of particle size that is remarkably captured quantitatively. Finally, a simple method is proposed to derive the parameters of the adhesion normal distribution from the Weibull parameters determined experimentally on single particle diametral compression tests. Method subspheres sub spheres literature However values function quantitatively Finally tests

Abstract The slope stability analyses are important to predict environmental, financial, and human life impacts. The Limit Equilibrium Method (LEM) is commonly used to estimate a slope’s Safety Factor (SF). However, the Finite Element Method (FEM) is increasingly applied to slope stability analyses, using different approaches, among which the technique of Shear Strength Reduction (SSR) is commonly used in perfectly plastic elastic models. The objective of this study is to present a discussion about these two methodologies, using critical state models with or without hardening will be used to model the stress-strain behavior of the soil mass. The results obtained in the case study presented, using LEM and FEM considering critical state models with and without hardening are consistent and allowed verifying the stability condition of the slope. Also, the reduction factors are smaller when compared to the results using perfectly plastic elastic models.

RESUMO A reciclagem é um tema que vem ganhando bastante espaço em diversas áreas da engenharia. Quando se reaproveita um material em obras civis, indiretamente se está contribuindo para a preservação da natureza. Dentro deste contexto, a reciclagem de revestimentos asfálticos é um assunto que desperta grande interesse, mas que requer estudos mais aprofundados. Desta forma, o presente trabalho tem como objetivo estudar os efeitos de produtos rejuvenescedores no comportamento de ligante asfáltico envelhecido, visando sua aplicação em reciclagem de revestimentos de pavimentos rodoviários. Para tanto, inicialmente foi extraído ligante residual e em seguida foram adicionados rejuvenescedores a base de alcatrão (RejuvaSeal) e outros a base de óleo de xisto, conhecidos comercialmente com AR-5, AR-250 e AR-500, nas taxas de 15, 20 e 25%, de modo a verificar qual teor seria apropriado para recuperar as características originais do ligante. Entre as diversas conclusões obtidas neste trabalho tem-se que a mistura contendo 20% de AR-5 apresenta o melhor comportamento quando comparada a um ligante asfáltico novo (CAP 50-70). As análises químicas e ambientais mostraram que a reciclagem de material fresado de revestimento asfáltico utilizando rejuvenescedor é uma solução tecnicamente possível e ambientalmente correta para pavimentação.

ABSTRACT Recycling is a topic that has been gaining enough space in various areas of engineering. When reuses material in civil works, indirectly it is contributing to the preservation of nature. Within this context, the recycling of asphalt coatings is a subject that arouses great interest, but that requires further study. Thus, this paper aims to study the effects of rejuvenating products on aged asphalt binder behavior, for their application in recycling road surface coatings. Therefore, it was initially extracted residual binder and then were added rejuvenating tar base (RejuvaSeal) and other shale oil based commercially known AR-5, AR-250 and AR500, at rates of 15, 20 and 25%, in order to see which content would be appropriate to recover the original characteristics of the binder. Among the many findings from this study is that the mixture containing 20% of AR-5 shows better behavior when compared to a new asphalt binder (CAP 50-70). The chemical and environmental analysis showed that the recycling of material milled using rejuvenating asphalt layer is a technically feasible solution for flooring and environmentally friendly.

Los autores proponen una nueva ley de endurecimiento para modelos constitutivos basados en el concepto subloading. Este concepto permite una transición suave entre la descarga y la recarga. Lo más importante es que caracteriza el suelo con un único grupo de parámetros, independientes de la densidad inicial. La nueva regla busca mejorar el modelo original propuesto por el último autor. La versión inicial incluía una regla de evolución lineal en aras de la simplicidad, sin incluir pruebas empíricas de dicha ley. Esta nueva versión propone una ley exponencial que se ajusta mejor los datos experimentales. Esta ley requiere sólo dos parámetros, con una interpretación física clara, obtenidos a partir de ensayos simples de compresión unidimensional. El modelo se basó en ensayos controlados con esferas de vidrio, sin embargo, fue aplicado a suelos granulares y arcillosos. Los resultados muestran que el modelo puede reproducir muy bien el comportamiento de suelos reales.

The authors propose a new hardening rule for constitutive models based on the subloading concept. This concept allows a smooth transition between unloading and reloading. Most importantly it characterizes the soil with a single set of parameters regardless of its initial density state. The new rule aims to improve the original model proposed by the last author. The original version included a linear evolution rule for the sake of simplicity, but did not include any empirical evidence for such law. This new version proposes an exponential law that provides a better fit to the experimental data. This law requires only two parameters with a clear physical interpretation. These parameters can be obtained from simple one-dimensional compression tests. The model was based on controlled tests performed with glass spheres, but was applied to real granular and clay soils. The results show that the model can very successfully reproduce the behavior of real soils.

Finalizando el año 2008 en la ciudad de Medellín, Colombia, ocurrió un deslizamiento de tierra en la urbanización Alto Verde provocando la muerte de doce personas y la destrucción de seis viviendas. Los deslizamientos se destacan por el elevado nivel de deformaciones en una masa de suelo. El presente trabajo utilizó el método del punto material (MPM), método basado en partículas que utiliza una doble discretización Lagrangiano-Euleriana. La doble discretización genera un marco numérico robusto que permite la simulación de grandes distorsiones. El modelo numérico planteó una simplificación de las condiciones geotécnicas, morfológicas y estructurales de las edificaciones envueltas en Alto Verde. El estado de deformación final de la simulación se acomodó satisfactoriamente a las características geométricas finales observadas en campo. Los resultados obtenidos generan aplicaciones como el diseño de barreras, análisis de riesgo o la determinación de la distancia mínima de retiro a una ladera susceptible de deslizamiento.

A huge landslide took place at Alto Verde residential complex at the end of 2008 in the city of Medellin, Colombia, claiming the lives of twelve people and destroying six houses. Landslides are characterized by large deformations in the soil mass. This study used the material point method (MPM), a particle-based method that takes advantage of a double Lagrangian-Eulerian discretization. This approach provides a robust framework that enables the numerical simulation of large strains, without mesh entanglement issues that are common with the Finite Element Method. The numerical model proposed here assumes simplifications of the geotechnical, morphological and structural buildings conditions on the site. Nevertheless, the final numerical deformed configuration described the geometric features observed in the field successfully. The result allows applications such as the design of barriers, risk assessment or determination of a minimum safe distance for a building from a slope susceptible to landslides.