Escuela de Politécnica Superior

Traditionally, in the construction sector it has been common to use materials indigenous to the construction site, such as bricks, cork, wood, etc. and this has significantly reduced energy costs and environmental impact. Similarly, there has been an adjustment of building design to local climatic conditions, resulting in improved building quality and thermal comfort for occupants. Currently, the massive use of global materials such as cement, aluminum, concrete, PVC, etc., has led to a significant increase in energy and environmental costs.

A partir de un modelo estructural básico, definido por nervios cuatripartitos de curvatura esquifada y bastidor horizontal de base, se realizan diferentes simulaciones numéricas por discretización de puntos, considerando el factor de forma de su geometría, variable. El método aplicado sirve para confirmar que el coeficiente de seguridad resultante de la comparación realizada a los modelos, se optimiza al reducir progresivamente la relación entre la superficie de la envolvente y el volumen encerrado por la estructura espacial. El modelo es sometido a la acción de cargas permanentes y acciones de viento con efecto prolongado en su aplicación cuasiestática. Se realiza un análisis del comportamiento sobre la estructura portante tanto de manera aislada como considerando las cargas totales, determinando por cada configuración de forma las zonas más desfavorables solicitadas y la evaluación de cargas dominantes. Asimismo se consideran en la modelización, los casos materiales para la estructura de acero al carbono en la parte inferior horizontal de la base, adoptando la solución tanto con aleación metálica de aluminio como de fibra de vidrio en la parte superior de los nervios cuatripartitos.

Partiendo de una estructura autoportante, se pretende mostrar las consideraciones y modificaciones de diseño llevadas a cabo para desarrollar la optimización de un suelo rígido acero-bambú para dicha estructura. Se justifica la elección de los materiales a través de sus propiedades mecánicas y coste, mostrando las ventajas del empleo del bambú como material de construcción. Con el propósito de lograr el mejor resultado en la optimización del modelo, se emplea como metodología de trabajo la simulación numérica por medio de elementos finitos utilizando el software comercial Abaqus. Se llevan a cabo distintas configuraciones dentro de la estructura autoportante (empleando elementos de refuerzo) y en la propia configuración geométrica de los paneles de bambú y de su soporte de acero, generando tres modelos diferentes (A, B y C), de tal forma que sea posible, en las tres opciones, elaborar un análisis que relacione tanto los esfuerzos generados como el desplazamiento y la deformación que sufre la base sometida a estudio. Finalmente se realiza una comparación de los resultados obtenidos por medio de las simulaciones, para concluir cuál de ellos consigue la optimización más adecuada del modelo, observándose cambios significativos en la flecha y ciertas variaciones en los esfuerzos internos.

According to the need of emergency houses all around the world, thedevelopment of a prototype (low cost and high strength structure) whichcould be placed anywhere becomes essential. This placement could be insusceptible areas to earthquakes, floods or armed conflicts. It has been studiedthe behaviour of a steel-bamboo hybrid structure compared with a steel-aluminiumhybrid one(in termsof strength).Finite elementssoftware hasbeenused to simulate both models. It has been obtained the maximum quantity ofbamboo which can be placed in the prototype achieving the optimum design.As far as strength is concerned, steel-aluminium is better than steel-bamboo;even though, it exists minimum difference (9.16%), which is despicableconsidering the advantages of bamboo. When using bamboo as alternativematerial, displacement varies because of the density of the elements. Thestructuralmodel becomeslighter and,according to that,it supposesan increasein the displacement (about 0.4 mm).

The use of supplementary cementitious materials has been widely accepted due to increasing global carbon emissions resulting from demand and the consequent production of Portland cement. Moreover, researchers are also working on complementing the strength deficiencies of concrete; fiber reinforcement is one of those techniques. This study aims to assess the influence of recycling wheat straw ash (WSA) as cement replacement material and coir/coconut fibers (CF) as reinforcement ingredients together on the mechanical properties, permeability and embodied carbon of concrete. A total of 255 concrete samples were prepared with 1:1.5:3 mix proportions at 0.52 water-cement ratio and these all-concrete specimens were cured for 28 days. It was revealed that the addition of 10 % WSA and 2 % CF in concrete were recorded the compressive, splitting tensile and flexural strengths by 33 MPa, 3.55 MPa and 5.16 MPa which is greater than control mix concrete at 28 days respectively. Moreover, it was also observed that the permeability of concrete incorporating 4 % of coir fiber and 20 % of WSA was reduced by 63.40 % than that of the control mix after 28 days which can prevent the propagation of major and minor cracks. In addition, the embodied carbon of concrete is getting reduced when the replacement level of cement with WSA along with CF increases in concrete. Furthermore, based on the results obtained, the optimum amount of WSA was suggested to be 10 % and that of coir fiber reinforcement was suggested to be 2 % for improved results.

Researchers are investigating eco-friendly binders like coconut shell ash (CSA), metakaolin (MK), and calcined clay (CC) as supplementary cementitious materials (SCM) in high-strength concrete (HSC). Abundantly available as industrial or agricultural waste, these materials, when combined with Portland cement (PC), offer synergistic benefits. This not only improves concrete performance but also addresses waste disposal issues, presenting a sustainable and environmentally friendly solution for long-term use in HSC production. However, this study performed on fresh and mechanical characteristics of HSC blended with CSA, MK, and CCA alone and together as SCM after 28 days of curing. A total of 504 samples of standard concrete were cast and the cubical samples were tested to achieve the targeted compressive strength about 80 MPa after 28 days. The experimental results indicated that the rise in tensile, flexural and compressive strengths of 9.62%, 8.27%, and 10.71% at 9% of CSA, MK, and CC as SCM after 28 days of curing. As SCM content increases, the density, porosity and water absorption of concrete decrease. Moreover, the workability of fresh concrete is getting reduced when the concentration of SCMs increases in HSC. In addition, the concrete’s sustainability assessment revealed that employing 18% MK, CC, and CSA as SCM reduced carbon emissions by approximately 11.78%. It is suggested that using 9% CC, MK and CSA together in HSC yields the best results for practical applications in civil engineering.

This article discusses the influence of the dimensions of the damping rings used for interrupting a dynamic tension experiment on the results of a modified split Hopkinson tension bar. The damping rings enclosed in an external fixture which modifies the classical split Hopkinson tension bar play a significant role in buffering the dynamic tension experiments before the specimen reaches its failure strength. Finite element simulations of high-strain-rate tension experiments are accomplished on Aluminium 7017-T73 alloy specimens when varying the thickness or the cross-sectional area of the damping rings. Finite element analyses described herein are applied to simulate the effects of the variation of the damping rings’ dimensions to provide a reference for improvement of a modified split Hopkinson tension bar experimental apparatus and guidance for future studies in which optimum dimensions for the damping rings can be studied. In view of this research, it can be concluded that the thickness of the damping rings is a factor that can resolutely influence the interrupted dynamic tension experiment results, while their cross-sectional area can be excluded as a factor influencing the results of the modified split Hopkinson tension bar experiments.

A new logistic model tree (LMT) model is developed to predict slope stability status based on an updated database including 627 slope stability cases with input parameters of unit weight, cohesion, angle of internal friction, slope angle, slope height and pore pressure ratio. The performance of the LMT model was assessed using statistical metrics, including accuracy (Acc), Matthews correlation coefficient (Mcc), area under the receiver operating characteristic curve (AUC) and F-score. The analysis of the Acc together with Mcc, AUC and F-score values for the slope stability suggests that the proposed LMT achieved better prediction results (Acc = 85.6%, Mcc = 0.713, AUC = 0.907, F-score for stable state = 0.967 and F-score for failed state = 0.923) as compared to other methods previously employed in the literature. Two case studies with ten slope stability events were used to verify the proposed LMT. It was found that the prediction results are completely consistent with the actual situation at the site. Finally, risk analysis was carried out, and the result also agrees with the actual conditions. Such probability results can be incorporated into risk analysis with the corresponding failure cost assessment later.

People may be exposed to energy sources that they cannot perceive with their senses, but which may be harmful to their organism, and therefore, individuals cannot avoid them. One of these energy sources is the sound, particularly sound out of the hearing range (20–20000 Hz). Although the sounds are imperceptible for frequencies below 200 Hz unless they have high intensities. Sound with frequencies below 200 Hz is called “low frequency sound”. This study focuses on low frequency sound generated by artificial sources, and specially in sound located in urban areas. Specifically in the measurement and detection of low frequency sources from the perspective of individuals who are manifesting the symptoms associated with their exposure. To this end, a household of Madrid with individuals who have symptoms is taken as sample. This home did not have large potential sources of low-frequency sounds near its location, such as streets with high intensity of traffic or the subway in order to better contrast other possible sources that are not so obvious. The results show high levels of sound emission at the lowest frequency range (20–200 Hz). These results also show that filters should not be applied to remove non-audible frequency spectrums, such as A type, because it omits sounds in urban areas that could affect people. Data treatment incorporates analysis methods based on machine learning which allow differentiate between sources without measuring on them. Finally, further developments must incorporate measurements bellow 20 Hz and will increase the numbers of households sampled.