Static and Dynamic Load Test of Libeň Bridge Over Vltava River in Prague and Concept of Repair

The Libeň bridge in Prague is a cultural and technical heritage of concrete construction of the beginning from the twentieth century. The bridge was designed by architect Pavel Janák, the founder of cubism in architecture. According to experts, the Libeň bridge is the only example of cubist morphology application on the bridge structure. Evaluation of Libeň bridge structural condition is an up-to-date topic leading to decision whether this bridge should be repaired or replaced by a new bridge. This article deals with the static and dynamic load testing in comparison with following creation and validation of the FEA model for load carrying capacity assessment of the Libeň Bridge and possible way of reconstruction. Paper deals with crucial procedures for FEA model validation of this backfilled arched concrete structure with a focus on the static characteristic of the structure. Article deals with reconstruction of the vault part of the Libeň Bridge using R-UHPFRC in terms of static operation. It focuses on the two basic problems of the bridge, the solution to increase the bearing capacity of the vault arches and to increase the bearing capacity of the foundations under pillars. The concept of repair is based on extensive diagnostic surveys conducted in 2017. The concept of structural enhancement is based on adding new thin layer of R-UHPFRC (reinforced, ultra-high performance concrete) on the upper vault surface. Concrete bridge structures are exposed to extreme effects of aggressive environmental influences, especially chlorides, which leads to damaging of most exposed bridge components a long time before their service life. UHPFRC material is suitable for repairs of these structures and especially due to its impermeability and high resistance

La importancia de los ácidos grasos en la leche materna y en las fórmulas lácteas

The best choice for feeding the newborn child is breast milk, and when it is not possible to breastfeed a baby, the breast milk is replaced by lacteal formula, which is why numerous studies focus their attention on the analysis of the diverse components of baby formula as well as functions in the breastfed baby. Fatty acids are components of great nutritional importance in the fetus and in the newborn child. Nowadays it is estimated that the fetus, during the last trimester of the gestational period and the newborn child, during the first six months of life, need a great contribution of araquidonic and docosahexaenoic acids, due to the fact that the speed of transformation of the predecessors to the hepatic level are not sufficient to cover the metabolic requirements of these fatty acids and it is the mother who contributes them through placental transport during gestation and her milk during lactation. The Organization of Food and Agriculture (FAO), the World Health Organization (WHO), the European Society of Gastroenterology, Hepatology and Pediatric Nutrition (ESPGHAN) and the American Academy of Pediatrics recommend that lacteal formula imitate the composition of the breast milk, especially in the fatty polyunsaturated acids (PUFA).<br><br>El alimento natural por excelencia para el recién nacido es la leche materna, cuando no es posible darla se sustituye por fórmulas lácteas, por lo que numerosos estudios enfocan su interés en el análisis de los diversos componentes de éstas, y sus funciones en el lactante. Los ácidos grasos son componentes de gran importancia nutricional tanto en el feto como en el recién nacido. Actualmente se estima que el feto, durante el último tercio del periodo gestacional y el recién nacido, durante los primeros seis meses de vida, requieren un gran aporte de ácidos araquidónico y docosahexaenoico, debido a que la velocidad de transformación de los precursores a nivel hepático no son suficientes para cubrir los requerimientos metabólicos de éstos ácidos grasos y es la madre quien los aporta a través del transporte placentario durante la gestación y a través de la leche durante la lactancia. La Organización para Alimentación y Agricultura (FAO), la Organización Mundial de la Salud (OMS) y la Sociedad Europea de Gastroenterología, Hepatología y Nutrición Pediátrica (ESPGHAN), así como la Academia Americana de Pediatría recomiendan que las fórmulas lácteas deben ser inocuas y similares a la composición de la leche humana y muy especialmente en los ácidos grasos poliinsaturados (PUFA)