Análisis mediante elementos finitos de cargas de impacto sobre el irradiador de Cobalto 60 de la Escuela Politécnica Nacional del Ecuador.

En el presente trabajo se determinó el posible agrietamiento en los muros estructurales y efectos en el funcionamiento del Irradiador Gamma Panorámico Categoría IV con Fuente de Cobalto 60 que se encuentra en el interior del Edificio n.º 7 de la Escuela Politécnica Nacional (EPN), en Quito. El estudio consistió en analizar el impacto de una parte del techo que está sobre el irradiador de la instalación denominada “CASAMATA”, puesto que gracias a un estudio previo de esta estructura se demostró que es vulnerable debido a sus características, construcción y deterioro a lo largo del tiempo. El estudio se realizó en función de requisitos de normas de análisis y evaluación de estructuras existentes, mediante la utilización del software denominado “SAP2000” para la modelación del irradiador. Se realizaron seis modelaciones con diferentes características en cuanto a hormigón y acero de refuerzo para determinar el comportamiento de la estructura bajo los casos asumidos. De los resultados obtenidos mediante SAP2000 se observó que en algunos lugares del irradiador se tienen valores mayores a los máximos permitidos en el American Concrete Institute 349 (ACI 349), correspondientes a la deformación unitaria del hormigón el cual es de 0.003 m/m. Además, los requisitos de resistencia señalados en la misma norma, no cumplieron con los parámetros establecidos, lo cual provoca que exista un peligro radiológico debido a que la cámara de radiación no cumpliría con el blindaje para la cual fue diseñada y liberaría una tasa de dosis mínima de 1.13x106 [mSv/año]The present work determines the possible cracking in the structural walls and effects on the operation of the Category IV Panoramic Gamma Irradiator with Cobalt 60 Source, which is located inside Building No. 7 of the National Polytechnic School (EPN) in Quito. The analysis consisted of an alleged (supposed) impact of a roof section that is on the irradiator in the facility called “CASAMATA”, since a previous study of this structure showed that it is vulnerable due to its characteristics, construction, and deterioration throughout the time. The study was carried out based on the requirements of analysis and evaluation standards of existing structures by using the software called SAP2000 for modeling the irradiator. Six models with different characteristics in terms of concrete and reinforcing steel were made to determine the behavior of the structure under the assumed cases. From the results obtained through SAP2000, it was observed that in some places of the irradiator there are values greater than the maximum allowed in the American Concrete Institute 349 (ACI 349) corresponding to the unitary deformation of the concrete, which is 0.003 m/m. In addition, the resistance requirements indicated in the same standard did not meet the established parameters, which causes a radiological hazard because the radiation chamber would not comply with the shielding for which it was designed and would release a minimum dose rate of 1.13x106 [mSv/year]

El Reporte preliminar de daños de 58 estructuras en Manta producidos por el sismo 16-A

This paper presents the first analyzes of the visits made in the disaster area, after the Pedernales earthquake of April 16, 2016. A group of engineers from the Faculty of Civil Engineering of the National Polytechnic School carry out primary structural evaluations, which they are reported in files established by the MIDUVI (The Ministry of Urban Development and Housing). Various maps are presented with the classification or damage class of 58 evaluated structures, of which emphasis is placed on 23 structures corresponding to health. Additionally, photos of failures and structural pathologies post-earthquake are presented, which show recurrent anomalies in structures in the locality. The activities carried out by the delegation of professionals and collaborators are briefly presented, it is expected for a future eventual seismic activity in the country that the population, authorities and construction professionals visualize the changes to be made, to avoid material and of lives losses. Identification parameters are established for safety evaluations in structures after an earthquake, where the green color corresponds to inspected and the occupation is legally allowed, for the yellow color corresponds to restricted use and occupation in certain areas is prohibited, for the color red corresponds to unsafe and occupation is prohibited.El presente estudio trata los primeros análisis de las visitas realizadas en la zona del desastre, posterior al sismo de Pedernales del 16 de abril del 2016. Un grupo de ingenieros de la Facultad de Ingeniería Civil de la Escuela Politécnica Nacional realizaron evaluaciones estructurales primarias que fueron reportadas en fichas establecidas por el MIDUVI (Ministerio de Desarrollo Urbano y Vivienda). Se realiza la presentación de varios mapas con la clasificación o semaforización de 58 estructuras evaluadas, de las cuales se hace énfasis en 23 estructuras correspondientes a centros de salud. Adicionalmente, se muestran fotos de fallas y patologías estructurales post-sismo que evidencian las anomalías recurrentes en estructuras de la localidad. Se exponen, resumidamente, las actividades realizadas por la delegación de profesionales y colaboradores. Se espera que para una futura eventual actividad sísmica en el país la población, las autoridades y los profesionales de la construcción visualicen los cambios por realizar para evitar las pérdidas materiales y de vidas. Se establecen parámetros de identificación para evaluaciones de seguridad en estructuras después de un sismo, en las que el color verde corresponde a inspeccionado y ocupación legalmente permitida, para el color amarillo corresponde a uso restringido y prohibición de ocupación en ciertas áreas y para el color rojo corresponde a inseguro y prohibición de ocupación

Reporte preliminar de daños de 58 estructuras en Manta producidos por el sismo 16-A

This paper presents the first analyzes of the visits made in the disaster area, after the Pedernales earthquake of April 16, 2016. A group of engineers from the Faculty of Civil Engineering of the National Polytechnic School carry out primary structural evaluations, which they are reported in files established by the MIDUVI (The Ministry of Urban Development and Housing). Various maps are presented with the classification or damage class of 58 evaluated structures, of which emphasis is placed on 23 structures corresponding to health. Additionally, photos of failures and structural pathologies post-earthquake are presented, which show recurrent anomalies in structures in the locality. The activities carried out by the delegation of professionals and collaborators are briefly presented, it is expected for a future eventual seismic activity in the country that the population, authorities and construction professionals visualize the changes to be made, to avoid material and of lives losses. Identification parameters are established for safety evaluations in structures after an earthquake, where the green color corresponds to inspected and the occupation is legally allowed, for the yellow color corresponds to restricted use and occupation in certain areas is prohibited, for the color red corresponds to unsafe and occupation is prohibited. El presente estudio trata los primeros análisis de las visitas realizadas en la zona del desastre, posterior al sismo de Pedernales del 16 de abril del 2016. Un grupo de ingenieros de la Facultad de Ingeniería Civil de la Escuela Politécnica Nacional realizaron evaluaciones estructurales primarias que fueron reportadas en fichas establecidas por el MIDUVI (Ministerio de Desarrollo Urbano y Vivienda). Se realiza la presentación de varios mapas con la clasificación o semaforización de 58 estructuras evaluadas, de las cuales se hace énfasis en 23 estructuras correspondientes a centros de salud. Adicionalmente, se muestran fotos de fallas y patologías estructurales post-sismo que evidencian las anomalías recurrentes en estructuras de la localidad. Se exponen, resumidamente, las actividades realizadas por la delegación de profesionales y colaboradores. Se espera que para una futura eventual actividad sísmica en el país la población, las autoridades y los profesionales de la construcción visualicen los cambios por realizar para evitar las pérdidas materiales y de vidas. Se establecen parámetros de identificación para evaluaciones de seguridad en estructuras después de un sismo, en las que el color verde corresponde a inspeccionado y ocupación legalmente permitida, para el color amarillo corresponde a uso restringido y prohibición de ocupación en ciertas áreas y para el color rojo corresponde a inseguro y prohibición de ocupación.&nbsp

Test Method for Studying the Shrinkage Effect under Controlled Environmental Conditions for Concrete Reinforced with Coconut Fibres

This study proposes a novel test method and corresponding procedure to evaluate how coconut fibres affect crack propagation rates resulting from plastic shrinkage during the accelerated drying of concrete slabs. The experiment employed concrete plate specimens, which were used to simulate slab structural elements with a surface dimension notably greater than their thickness. These slabs were reinforced with coconut fibre with 0.5%, 0.75%, and 1% fibre content. A wind tunnel was designed to simulate two significant climate parameters (wind speed and air temperature), which could impact the cracking behaviour of surface elements. The proposed wind tunnel allowed air temperature to be controlled alongside wind speed while monitoring moisture loss and the cracking propagation process. During testing, a photographic recording method was used to evaluate cracking behaviour, with the total crack length serving as a parameter to assess the impact of fibre content on the crack propagation of slab surfaces. Additionally, crack depth was measured using ultrasound equipment. The results indicate that the proposed test method was appropriate for future research, allowing for the evaluation of the effect of natural fibres on the plastic shrinkage behaviour of surface elements under controlled environmental conditions. Based on initial studies and the results obtained through the proposed test method, concrete containing 0.75% fibre content exhibited significantly reduced crack propagation on slab surfaces, as well as a reduction in the crack depth caused by plastic shrinkage during the early age of the concrete

Coconut-Fiber Composite Concrete: Assessment of Mechanical Performance and Environmental Benefits

The purpose of this qualification work is to study the physical and mechanical behavior of concrete with the addition of 0.5% and 1% coconut fiber, which has been subjected to two chemical treatments to reduce its degradation. The coconut fibers were extracted from the raw material and cut into pieces 4 cm long. Subsequently, the fibers were subjected to two chemical treatments. The first involved immersing the fibers in 4% sodium hydroxide (NaOH) solution, and the second treatment involved coating them with gum arabic and silica fume. A total of 50 samples of fibers were collected in their natural and post-treated state to be tested. The dosage was prepared for design strengths of 210 and 240 kg/cm2 (20.59 and 23.54 MPa), so that the percentages of 0.5% and 1% volume of coconut fiber, for the two treatments selected, replaced the respective volume of coarse aggregates. The cylinders with 1% addition of fibers had the best performance for the design strength of 20.59 MPa, including the cylinders without fibers. Those with 0.5% addition of fibers presented better performance for the 23.54 MPa dosage, although this was lower than the cylinders without fibers. In all cases, the cylinders with NaOH-treated fibers outperformed their counterparts with fibers treated with gum arabic and silica fume. Finally, a CO2 balance was determined, and an environmental gain up to 14 kg in CO2 emissions was established for each cubic meter of composite concrete