Efecto del grado de capacidad de disipación de energía sísmica seleccionado en las cantidades de obra de muros de concreto reforzado

Context: Regarding their design of reinforced concrete structural walls, the Colombian seismic design building code allows the engineer to select one of the three seismic energy dissipation capacity (ordinary, moderate, and special) depending on the seismic hazard of the site. Despite this, it is a common practice to choose the minor requirement for the site because it is thought that selecting a higher requirement will lead to larger structural materials amounts and, therefore, cost increments. Method: In this work, an analytical study was performed in order to determine the effect of the selected energy dissipation capacity on the quantity of materials and ductility displacement capacity of R/C walls. The study was done for a region with low seismic hazard, mainly because this permitted to explore and compare the use of the three seismic energy dissipations capacities. The effect of different parameters such as the wall total height and thickness, the tributary loaded area, and the minimum volumetric steel ratio were studied.Results: The total amount of steel required for the walls with moderate and special energy dissipation capacity corresponds, on average, to 77% and 89%, respectively, of the quantity required for walls with minimum capacity.Conclusions: it is possible to achieve reductions in the total steel required weight when adopting either moderated or special seismic energy dissipation instead of the minimum capacity.  Additionally, a significant increment in the seismic ductility displacements capacity of the wall was obtained.Contexto: Para el diseño de muros estructurales de concreto reforzado, la normativa sismoresistente en Colombia permite, en función de la amenaza sísmica del sitio, optar por uno de tres posibles grados de capacidad de disipación de energía (mínima, moderada y especial). Sin embargo, la práctica empleada es la de adoptar el menor grado acorde a la amenaza sísmica. Método: En este trabajo se realizó un estudio analítico del efecto del grado de capacidad de disipación de energía seleccionado durante el diseño de muros estructurales de concreto reforzado, en las cantidades de obra de la estructura y en la capacidad de desplazamiento. El estudio se centró en zonas de amenaza sísmica baja, ya que permite explorar y comparar los tres grados de disipación de energía. En el estudio se incluyeron otras variables como la altura total del muro, el área tributaria y la cuantía mínima de refuerzo adoptada para el alma del muro.Resultados: la cantidad total de acero requerida para los muros con capacidad moderada y especial corresponde, en promedio, a un 77% y 89%, respectivamente, de la cantidad requerida para los muros con capacidad mínima.Conclusiones: es posible lograr reducciones en el peso total de acero requerido al emplear grados de capacidad de disipación moderada y especial comparado con el uso de capacidad de disipación mínima. Además, con esta estrategia se lograr un incremento significativo en la ductilidad del muro.

Effect of the selected seismic energy dissipation capacity on the materials quantity for reinforced concrete walls

Context: Regarding their design of reinforced concrete structural walls, the Colombian seismic design building code allows the engineer to select one of the three seismic energy dissipation capacity (ordinary, moderate, and special) depending on the seismic hazard of the site. Despite this, it is a common practice to choose the minor requirement for the site because it is thought that selecting a higher requirement will lead to larger structural materials amounts and, therefore, cost increments.  Method: In this work, an analytical study was performed in order to determine the effect of the selected energy dissipation capacity on the quantity of materials and ductility displacement capacity of R/C walls. The study was done for a region with low seismic hazard, mainly because this permitted to explore and compare the use of the three seismic energy dissipations capacities. The effect of different parameters such as the wall total height and thickness, the tributary loaded area, and the minimum volumetric steel ratio were studied. Results: The total amount of steel required for the walls with moderate and special energy dissipation capacity corresponds, on average, to 77% and 89%, respectively, of the quantity required for walls with minimum capacity. Conclusions: it is possible to achieve reductions in the total steel required weight when adopting either moderated or special seismic energy dissipation instead of the minimum capacity.  Additionally, a significant increment in the seismic ductility displacements capacity of the wall was obtained

Efecto del grado de capacidad de disipación de energía sísmica seleccionado en las cantidades de obra de muros de concreto reforzado

Context: Regarding their design of reinforced concrete structural walls, the Colombian seismic design building code allows the engineer to select one of the three seismic energy dissipation capacity (ordinary, moderate, and special) depending on the seismic hazard of the site. Despite this, it is a common practice to choose the minor requirement for the site because it is thought that selecting a higher requirement will lead to larger structural materials amounts and, therefore, cost increments. Method: In this work, an analytical study was performed in order to determine the effect of the selected energy dissipation capacity on the quantity of materials and ductility displacement capacity of R/C walls. The study was done for a region with low seismic hazard, mainly because this permitted to explore and compare the use of the three seismic energy dissipations capacities. The effect of different parameters such as the wall total height and thickness, the tributary loaded area, and the minimum volumetric steel ratio were studied.Results: The total amount of steel required for the walls with moderate and special energy dissipation capacity corresponds, on average, to 77% and 89%, respectively, of the quantity required for walls with minimum capacity.Conclusions: it is possible to achieve reductions in the total steel required weight when adopting either moderated or special seismic energy dissipation instead of the minimum capacity.  Additionally, a significant increment in the seismic ductility displacements capacity of the wall was obtained.Contexto: Para el diseño de muros estructurales de concreto reforzado, la normativa sismoresistente en Colombia permite, en función de la amenaza sísmica del sitio, optar por uno de tres posibles grados de capacidad de disipación de energía (mínima, moderada y especial). Sin embargo, la práctica empleada es la de adoptar el menor grado acorde a la amenaza sísmica. Método: En este trabajo se realizó un estudio analítico del efecto del grado de capacidad de disipación de energía seleccionado durante el diseño de muros estructurales de concreto reforzado, en las cantidades de obra de la estructura y en la capacidad de desplazamiento. El estudio se centró en zonas de amenaza sísmica baja, ya que permite explorar y comparar los tres grados de disipación de energía. En el estudio se incluyeron otras variables como la altura total del muro, el área tributaria y la cuantía mínima de refuerzo adoptada para el alma del muro.Resultados: la cantidad total de acero requerida para los muros con capacidad moderada y especial corresponde, en promedio, a un 77% y 89%, respectivamente, de la cantidad requerida para los muros con capacidad mínima.Conclusiones: es posible lograr reducciones en el peso total de acero requerido al emplear grados de capacidad de disipación moderada y especial comparado con el uso de capacidad de disipación mínima. Además, con esta estrategia se lograr un incremento significativo en la ductilidad del muro.

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially