3 research outputs found
Selección y modificación de registros sísmicos para análisis no lineal de muelles
Magíster en Ingeniería CivilMaestrí
Evaluación técnica y económica del concreto no convencional fabricado a partir de agregados provenientes del reciclaje de escombros de concreto
El presente proyecto consiste en desarrollar una investigación experimental en laboratorio de tipo exploratorio, para determinar las características técnicas que tienen los agregados gruesos producto de la demolición y trituración de estructuras de concreto simple y concreto armado simple, para luego compararlas con los correspondientes agregados convencionales y así poder determinar su viabilidad económica. El problema a resolver puede abordarse desde dos enfoques:
• Enfoque técnico - económico
El problema radica en el desconocimiento general que existe en la región nariñense del comportamiento físico-mecánico que poseen los agregados reciclados antes mencionados en la conformación de concretos hidráulicos. Este problema se abordará comparando la resistencia a la compresión simple en cilindros hechos con concreto no convencional (conformado por agregados gruesos reciclados) y cilindros de concreto convencional (conformados con agregados naturales), para luego realizar con estos agregados reciclados un análisis técnico como material de construcción y un análisis económico como una alternativa a los materiales naturales.
La investigación logrará establecer las características físico-mecánicas de los agregados provenientes del reciclaje de estructuras de concreto y su comportamiento dentro de la matriz de los agregados que conforman el concreto hidráulico, conociéndose al final si son adecuados para la construcción de estructuras que lleven en su interior concreto simple.
• Enfoque ambiental
Durante la realización de una obra civil es habitual que se deba derribar una construcción existente, lo que origina una cantidad importante de residuos en forma de sobrantes y de diversos restos; siendo este uno de los problemas medio ambientales más importantes, el cual provoca la degradación del paisaje cuando se vierten de manera incontrolada.
Es por eso que hoy, la exigencia de una mejora en la protección del medio ambiente y la preservación de la naturaleza y del paisaje motivan a que, en el ámbito de la construcción, se controlen estos residuos por medio de una gestión adecuada, minimizando las cantidades de los residuos desechados y haciendo que estos puedan ser reciclados, y en el mejor de los casos, reutilizados. Es por ello que se hace urgente el conocimiento y la compresión del comportamiento mecánico de los escombros de construcción como el concreto, con el objetivo de poder reutilizarlos, creando obras civiles cómodas, seguras y económicas, y subsanar el problema de la disposición final de escombros. La importancia del proyecto radica en que en el medio no existen investigaciones que traten el reciclaje de los residuos de construcción como una alternativa técnico-económica, que adicionalmente trae consigo mejoras medioambientales
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Effects of pre-operative isolation on postoperative pulmonary complications after elective surgery: an international prospective cohort study an international prospective cohort study
We aimed to determine the impact of pre-operative isolation on postoperative pulmonary complications after elective surgery during the global SARS-CoV-2 pandemic. We performed an international prospective cohort study including patients undergoing elective surgery in October 2020. Isolation was defined as the period before surgery during which patients did not leave their house or receive visitors from outside their household. The primary outcome was postoperative pulmonary complications, adjusted in multivariable models for measured confounders. Pre-defined sub-group analyses were performed for the primary outcome. A total of 96,454 patients from 114 countries were included and overall, 26,948 (27.9%) patients isolated before surgery. Postoperative pulmonary complications were recorded in 1947 (2.0%) patients of which 227 (11.7%) were associated with SARS-CoV-2 infection. Patients who isolated pre-operatively were older, had more respiratory comorbidities and were more commonly from areas of high SARS-CoV-2 incidence and high-income countries. Although the overall rates of postoperative pulmonary complications were similar in those that isolated and those that did not (2.1% vs 2.0%, respectively), isolation was associated with higher rates of postoperative pulmonary complications after adjustment (adjusted OR 1.20, 95%CI 1.05–1.36, p = 0.005). Sensitivity analyses revealed no further differences when patients were categorised by: pre-operative testing; use of COVID-19-free pathways; or community SARS-CoV-2 prevalence. The rate of postoperative pulmonary complications increased with periods of isolation longer than 3 days, with an OR (95%CI) at 4–7 days or ≥ 8 days of 1.25 (1.04–1.48), p = 0.015 and 1.31 (1.11–1.55), p = 0.001, respectively. Isolation before elective surgery might be associated with a small but clinically important increased risk of postoperative pulmonary complications. Longer periods of isolation showed no reduction in the risk of postoperative pulmonary complications. These findings have significant implications for global provision of elective surgical care. We aimed to determine the impact of pre-operative isolation on postoperative pulmonary complications after elective surgery during the global SARS-CoV-2 pandemic. We performed an international prospective cohort study including patients undergoing elective surgery in October 2020. Isolation was defined as the period before surgery during which patients did not leave their house or receive visitors from outside their household. The primary outcome was postoperative pulmonary complications, adjusted in multivariable models for measured confounders. Pre-defined sub-group analyses were performed for the primary outcome. A total of 96,454 patients from 114 countries were included and overall, 26,948 (27.9%) patients isolated before surgery. Postoperative pulmonary complications were recorded in 1947 (2.0%) patients of which 227 (11.7%) were associated with SARS-CoV-2 infection. Patients who isolated pre-operatively were older, had more respiratory comorbidities and were more commonly from areas of high SARS-CoV-2 incidence and high-income countries. Although the overall rates of postoperative pulmonary complications were similar in those that isolated and those that did not (2.1% vs 2.0%, respectively), isolation was associated with higher rates of postoperative pulmonary complications after adjustment (adjusted OR 1.20, 95%CI 1.05–1.36, p = 0.005). Sensitivity analyses revealed no further differences when patients were categorised by: pre-operative testing; use of COVID-19-free pathways; or community SARS-CoV-2 prevalence. The rate of postoperative pulmonary complications increased with periods of isolation longer than 3 days, with an OR (95%CI) at 4–7 days or ≥ 8 days of 1.25 (1.04–1.48), p = 0.015 and 1.31 (1.11–1.55), p = 0.001, respectively. Isolation before elective surgery might be associated with a small but clinically important increased risk of postoperative pulmonary complications. Longer periods of isolation showed no reduction in the risk of postoperative pulmonary complications. These findings have significant implications for global provision of elective surgical care