Se encontraron 35 investigaciones
The possibility of using mortarless reinforced masonry walls made of concrete units in seismic regions of Peru is examined through an experimental project. The absence of mortar in the joints of the wall made of stacked units could reduce the seismic capacity; however, such wall is built in less time than traditional walls. A comparison is done between two reinforced walls, subjected to in plane cyclic lateral load tests. One wall was built in the traditional way, while the second wall was built of stacked units without using mortar in the joints. Control tests were also performed on the concrete block units and on masonry prisms. All the construction and tests were done in the Structures Laboratory of the Catholic University of Peru. The comparison also took into account the construction process, the construction time, as well as the cost of the walls, in order to evaluate if the mortarless wall is economically and structurally worth. The results indicate a similar behavior between the two types of masonry (traditional and stacked units without mortar); only the cracks developed under very high loads were different. Therefore, the mortarless masonry walls with stacked units could be acceptable for seismic purposes.
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Many housing buildings in Peru are being constructed using partition walls made of silica lime (calcium silicate or sand lime) units, called ¿Placa P-7¿ or ¿Placa P-10¿ in Peru, of 70 or 100 mm thickness, filled with grout. In the beginning years, when the P-7 walls were introduced in buildings, the units were placed stack bonded with continuous vertical joints, as pillars. Lately, these walls are being built with the units overlapping at half blocks [CML Lacasa, 2014]. The paper presents an experimental test series, using a RC frame with two P-7 partition walls, one with the stacked bonded units, and the other with overlapping units. The vertical reinforcement in both walls consisted in overlapping vertical bars anchored into the bottom and upper beams. The frame with the two partition walls was subjected to out-of-plane seismic simulation tests in the shaking table of the Structures Laboratory of the Pontificia Universidad Catolica del Perú. Both walls resisted all the shakings with large lateral displacements. It is recommended that a drift limit should be established to avoid panic. Afterwards, a static test was performed, rotating the walls 90° to a horizontal plane, and subjecting them to vertical loads. The chemical anchorage of the vertical reinforcement bars worked well, the failure occurred at the mid zone of the partition wall.
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In recent years in Peru, many parapet walls or sills in buildings are built with silica lime masonry units of 100-mm thickness (called placa P-10 in Peru). Their behaviour under out-of-plane forces due to a severe earthquake is yet unknown, despite that the failure by overturning of the parapets could be extremely dangerous. This paper deals with the experimental behaviour of four different P-10 parapets under out-of-plane forces. The tests consisted in shaking table tests and static monotonic loads, performed at the Structures Laboratory of the Catholic University of Peru. The dimensions of the four walls were 1.53 m long, 0.9 m tall, and 100 mm thickness. They were constructed with different specifications, using the same construction materials and workmanship. After visiting several buildings under construction, we selected the worst and the best construction technique of P-10 parapets, in order to compare them with the producer¿s specifications.
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In Peru, many parapet walls in medium or tall buildings are built without care of their behavior under out-of-plane seismic forces. This paper deals with the experimental out-of-plane seismic tests on four different parapet brick masonry walls, performed at the Structures Laboratory of the Catholic University of Peru, with different bracing conditions. The clay brick wall parapets were constructed of 1.2 m long, 1m high and 120mm thickness over an RC foundation. Two RC square columns (120 mm side) were later added as lateral braces in three of the specimens, using a toothed connection, simulating the retrofit to an existing parapet wall. The variations were in the reinforcement bars and the anchorage into the bottom beam. The four parapet walls were constructed using the same construction materials and workmanship. The experimental results of shaking table tests and static test are discussed, giving warnings to unbraced masonry walls which collapsed under a moderate earthquake.
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El terremoto de Enero del 2010 en Haití demostró que el sistema constructivo predominante en ese país, la albañilería con bloque de concreto vibrado o artesanal, no es sismorresistente. Por otra parte, la albañilería de ladrillos de arcilla confinada con elementos de concreto armado es una técnica constructiva ampliamente difundida en algunos países de América Latina y otras partes del mundo, que ha demostrado tener un buen desempeño sísmico. Este proyecto partirá de la caracterización del sistema constructivo tradicional para introducir mejoras en su resistencia y ductilidad. Se busca incorporar refuerzos factibles de usar en Haití para lograr que la albañilería de bloques de concreto, con elementos de confinamiento adecuados, sea capaz de soportar un evento sísmico importante. En esta etapa se propone realizar una serie de ensayos en el Laboratorio de Estructuras de la PUCP para estudiar los elementos de albañilería. El objeto es cuantificar y optimizar la mejora obtenida al adaptar las recomendaciones constructivas de la albañilería confinada de ladrillos de arcilla, al sistema de bloques de concreto que se emplean en Haití. El objetivo final del proyecto es aportar recomendaciones para una solución técnicamente comprobada y económicamente accesible que se pueda aplicar en la reconstrucción de las ciudades devastadas en Haití.
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Se conoce que los muros tradicionales de adobe colapsan en forma frágil cuando están expuestos a la acción de agua por un período largo de tiempo. Las lluvias copiosas que incrementan el caudal de los ríos producen inundaciones frecuentes que pueden afectar a las casas de adobe que se construyen en las áreas inundables, lo cual es común en el Perú. Para evitar dichos colapsos, tres técnicas experimentales se estudiaron en el Laboratorio de Estructuras de la Universidad Católica del Perú, con resultados satisfactorios. Las técnicas estudiadas fueron simples y económicas, y tuvieron el objetivo de proteger la base de los muros de adobe para evitar los efectos negativos de la acción del agua. El muro MC se construyó con un sobrecimiento de concreto en reemplazo de las hiladas inferiores de adobes. En el muro ME las hiladas inferiores expuestas al agua tuvieron unidades de adobe especiales, estabilizadas con 5% de cemento. El muro MT tuvo un tarrajeo externo de mortero de cemento aplicado sobre una malla de alambre conectada al muro. Adicionalmente, con fines comparativos, se ensayó un muro tradicional (MP). Los ensayos realizados fueron: succión y absorción de las unidades de adobe, y un ensayo de inundación de los cuatro muros. Los cuatro muros fueron construidos sobre un canal de concreto armado dividido en cuatro partes similares. El muro MP colapsó en forma frágil después de sólo 20 minutos de exposición al agua, similar a las casas reales de adobe en áreas inundadas. De otro lado, los muros MC, ME, y MT soportaron más de 16 días sin daños. El excelente comportamiento alcanzado muestra que es posible proteger las casas de adobe contra las inundaciones con técnicas simples y económicas.
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El terremoto del 2010 en Haití mostró que la albañilería allí usada con bloques de concreto artesanales, no es sismorresistente. Por otra parte, la albañilería confinada con elementos de concreto armado es una técnica constructiva ampliamente difundida en algunos países de América Latina, que ha demostrado tener un buen desempeño sísmico. Este proyecto pretende introducir mejoras en el comportamiento sísmico de la albañilería típica de Haití, mediante el aumento de la resistencia y la ductilidad estructural. Se hicieron ensayos de laboratorio con muros de albañilería de bloques de concreto a escala natural que incorporaron condiciones factibles de usar en Haití. Estas fueron: a) dos formas de relleno de los alveolos (33% y 66%) de las unidades previas al asentado en el muro para aumentar la resistencia; y b) variar el proceso constructivo con los elementos de confinamiento de concreto vaciados luego de la construcción del muro de albañilería para mejorar la ductilidad. Los resultados indicaron que el comportamiento sísmico de los muros de albañilería confinados con rellenos de 66% de los alveolos, mejora en forma significativa y es factible constructivamente.
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This paper describes the shaking table tests performed on three full-scale confined masonry models in Peru in 2008, due to an agreement between several Japanese institutions and the Catholic University of Peru. The purpose of the experimental program was to observe the performance of low quality masonry constructions similar to those found in seismic active regions of South-East Asia (Indonesia, Pakistan, etc.), and to study two approaches in order to improve their seismic behavior. The models were built of hand-made clay bricks, laid with low quality mortar, and confined by columns and beams of low strength concrete. The overall dimensions of the models were 3x3m plan and 3 m height. The materials low quality properties were below the minimum required by the Peruvian Masonry Code (SENCICO 2006). The basic first model had no extra reinforcement. The second model had internal reinforcement with small wires to connect the masonry walls to the confining columns and a continuous lintel beam. The third model was similar to the first one, with external wire meshes covering the wall surfaces. Preliminary conclusions are given regarding the observed behavior and response. The international cooperation possibilities are emphasized to aid earthquake-prone countries without important research on masonry constructions.
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