68 research outputs found
Numerical modelling of in-plane behaviour of adobe walls
Some tests for material characterization of adobe blocks and adobe masonry have been carried out in universities and laboratories around the world. However, the number of tests is quite limited in comparison with those carried out with other structural materials, such as masonry or reinforced concrete, and even those tests just refers to elastic properties. The results of adobe tests (i.e. compression strength, elasticity modulus, shear strength, etc.), as well as the results of cyclic and dynamic tests on adobe masonry components and small buildings show that the mechanical properties of adobe masonry and the seismic performance of adobe constructions highly depend on the type of soil used for the production of units and mortar. Basic properties, such as elasticity modulus, can have significant variation from one soil type to another.
The state-of-the-art for the numerical modelling of unreinforced masonry point to three main approaches: macro-modelling, simplified micro-modelling and detailed micro-modelling. In all three approaches, the use of elastic and inelastic parameters is required. For adobe masonry, the lack of knowledge concerning some of the material properties makes numerical modelling more difficult.
In the proposed work, the mechanical properties of the typical adobe masonry in Peru have been calibrated based on a cyclic in-plane test carried out on an adobe wall at the Catholic University of Peru (PUCP). The mechanical parameters calibration and the modelling results of the in-plane behaviour of the adobe wall are presented. Macro-modelling and simplified micro-modelling strategies are used in finite element software with an implicit solution strategy. The results of this work represent the first step for the numerical modelling of the seismic behaviour of adobe constructions
The use of continuum models for analyzing adobe structures
As it is known, the adobe structures have a high seismic vulnerability principally due to the low material strength
and sometimes due to the inadequate structural configuration. One way for understanding the seismic behaviour
of these structures is by experimental tests. However, those are costly and sometimes not easy to make. An
alternative for this is the analysis of adobe structures by numerical tools with the possibility to make parametric
studies for understanding the behaviour of different geometrical configurations.
In a previous work, some adobe material parameters have been calibrated based on a cyclic in-plane test. In this
paper, that work was extended to a numerical modelling of the non-linear dynamic behaviour of an adobe
module experimentally tested at the Pontificia Universidad Católica del Perú. For this, a continuum model in the
finite element program Abaqus/Explicit, was used to represent the adobe masonry as a homogeneous and isotropic material
Structural properties of adobe dwellings in Cusco (Peru) for seismic risk assessment
This paper looks at the structural properties of adobe buildings in
Cusco, Peru, for use in seismic risk assessment.
The geometrical properties (typology) of adobe dwellings from Cusco
have been established according to a building-by-building survey.
Cusco has been chosen for this study as, according to the national
census, around 80% of the building stock in this town is constructed
with adobe.
Furthermore, this region of the country is relatively seismically active
and thus seismic risk assessment studies are warranted. Additional
structural information of adobe buildings has been obtained from
experimental tests carried out at the Catholic University of Peru. These
tests have allowed the inter-storey drift capacity and the period of
vibration of adobe buildings to be derived.
A database containing the principal geometrical properties of 30
dwellings has been created which has allowed the mean, standard
deviation and probability density functions (PDF) to be defined for
each parameter such as storey height, wall length, etc.
These properties are of use in a recently proposed probabilistic displacement-
based earthquake loss assessment method (DBELA) which
generates random populations of buildings based on this input data.
The structural capacity of each random building is then predicted
based on structural mechanics principles, and by comparing this
capacity with the demand from earthquakes, estimates of the probability
of damage can be made
Seismic capacity of adobe dwellings
In this paper the seismic capacity of adobe dwellings, in-plane and out-of-plane, is analyzed in terms of the displacement capacity and the period of vibration. For the former, cyclic and dynamic tests carried out at the Catholic University of Peru (PUCP) has been analyzed to obtain limit states (LS) for adobe walls and damping values for each LS. The period of vibration obtained from the experimental test results were compared with the results of elastic numerical analysis, where different configurations of adobe buildings were simulated. Then, an expression to compute the elastic period of vibration of adobe dwellings was obtained in function of the walls height. For the out-of-plane behaviour the displacement capacity is obtained from a linearized displacement-based approach, which estimates the maximum displacement that an adobe wall can support without collapsing. The period of vibration is obtained based on the collapse mechanism selected for each wall, which is a function of the wall geometrical properties and the boundary conditions
Parámetros estructurales de las viviendas de adobe (Cusco, Perú) para la evaluación del desempeño sísmico
En este trabajo se evalúan las propiedades estructurales de las construcciones de adobe en
Cusco, Perú, para ser usadas como parámetros en la evaluación de la capacidad y del riesgo
sísmico. Las propiedades geométricas (tipología) de las viviendas de adobe han sido
determinadas a través de encuestas de campo en un trabajo anterior. Con la información
recopilada se creó una base de datos resaltando la media, desviación estándar y funciones de
distribución de probabilidad (FDP) de cada uno de los parámetros como la altura de la vivienda,
ancho de muros, dimensiones de los adobes, etc. La ciudad del Cusco ha sido seleccionada
para este estudio por ser una de las ciudades con mayor cantidad de viviendas de tierra en el
Perú, país con intensa actividad sísmica. La información sobre el comportamiento sísmico de
las construcciones de adobe ha sido obtenida a través de ensayos experimentales realizados
en la Pontificia Universidad Católica del Perú (PUCP). Los resultados de estos ensayos han
permitido desarrollar expresiones para el cálculo de la deriva (capacidad de deformación) y del
período de vibración de las viviendas de adobe. En base a estas ecuaciones, la capacidad
sísmica de las viviendas de tierra del Cusco ha sido calculada y usada en una reciente
propuesta probabilística de la estimación de pérdidas por terremotos basada en
desplazamientos (acrónimo DBELA). Esta metodología plantea la generación de una población
aleatoria de viviendas siguiendo la información estadística de las propiedades geométricas.
Luego, la capacidad estructural de cada vivienda aleatoria es calculada (capacidad de
desplazamiento vs. período de vibración) y comparada con la demanda sísmica, obteniéndose
de esta forma probabilidades de daños (curvas de vulnerabilidad).This paper looks at the structural properties of adobe buildings in Cusco, Peru, for use in
seismic performance and seismic risk assessment. The geometrical properties (typology) of
adobe dwellings from Cusco have been established according to a building-by-building survey.
Cusco has been chosen for this study as, according to the national census, around 80% of the
building stock in this town is constructed with adobe. Furthermore, this region of the country is
relatively seismically active and thus seismic risk assessment studies are warranted. Additional
structural information of adobe buildings has been obtained from experimental tests carried out
at the Catholic University of Peru. These tests have allowed the inter-storey drift capacity and
the period of vibration of adobe buildings to be derived. A database containing the principal
geometrical properties of 30 dwellings has been created which has allowed the mean, standard
deviation and probability density functions (PDF) to be defined for each parameter such as
storey height, wall length, etc. These properties are of use in a recently proposed probabilistic
displacement-based earthquake loss assessment method (DBELA) which generates random
populations of buildings based on this input data. The structural capacity of each random
building is then predicted based on structural mechanics principles, and by comparing this
capacity with the demand from earthquakes, estimates of the probability of damage can be
made
Structural properties of adobe dwellings in Cusco for seismic risk assessment
According to the last national census, 35% of the Peruvian dwellings are made with adobe or tapial (rammed earth). In Cusco, a city located at the Peruvian highlands, around 75% of the building stock is constructed with earth. Besides, Cusco is relatively seismically active and thus seismic risk assessment studies are warranted. For example, on May 21, 1950, an earthquake seriously damaged almost all the buildings in Cusco, which a maximum estimated acceleration of 300 gals. This work looks at the structural properties of adobe buildings in Cusco for use in seismic risk assessment. The geometrical properties of typical dwellings from Cusco have been established according to a building-by-building survey carried out at the Catholic University of Peru (PUCP). Then, a database containing the principal geometrical properties of 30 dwellings has been created which has allowed the mean, standard deviation and probability density functions (PDF) to be defined for parameter such as storey height, wall length, etc
Seismic risk assessment of adobe dwellings in Cusco, Peru, based on mechanical procedures
A procedure to evaluate the seismic vulnerability of one-storey adobe dwellings located in Cusco (Peru) is presented here. The seismic capacity of these dwellings is based on a mechanical-based approach, where the in-plane and out-of-plane failure mechanisms are taken into account. From a database with the principal geometrical properties of dwellings from Cusco, random populations of buildings were generated through Monte Carlo simulation. The capacity of each random dwelling is expressed as a function of its displacement capacity and period of vibration, and this is evaluated for different damage limit states. The seismic demand has been represented by the displacement spectral shapes computed for different levels of intensity, considering the Peruvian Seismic Code and the Eurocode 8. Finally, from the comparison between capacity and demand, probability of failure have been obtained for different return periods
Resistance-Associated Substitutions/Variants Correlate to Therapeutic Outcomes of Novel Direct-Acting Antivirals in Different HCV Genotype Treated Individuals
The expanded classification of hepatitis C virus (HCV) genome into various genotypes and numerous subtypes significantly correlates to therapeutic outcomes of interferon-free direct-acting antivirals (DAAs) in HCV treated patients. In particular, genotypes 3 and 4 are still harder to treat, and higher sustained virologic response (SVR) rates are not achieved in some difficult-to-treat specific populations (i.e., HCV subtype 1a patients, compensated and decompensated cirrhotic patients, HCV/HIV co-infection, and prior treatment failure with pegylated interferon plus ribavirin and first-generation protease inhibitor based therapeutic regimens). Furthermore, the pre-existing and treatment-emergent resistance associated substitutions (RAS) at specific amino acid positions within the viral quasispecies may increase the chances of viral breakthrough (HCV RNA remains lower limit of quantification, but increased to 100 IU/mL or 1.log10 during DAAs therapy), viral relapse (undetectable viral load at the end of treatment but positive within the follow-up of 6 months), and discontinuation of therapy in treated individuals. Although the clinical importance of RAS is not entirely elucidated, it is believed that such substitutions decrease the therapeutic efficacy of DAAs in treated individuals. Similarly, the emergence of multiclass hepatitis C virus resistance to interferon-free DAAs failure in real-world experiences demands eagerly tailored second-line anti-hepatitis C therapies. This book chapter comprehensively overviews the clinical correlation of HCV genotypes, viral quasispecies and harboring RAS to treatment outcomes of revolutionary interferon-free DAAs in hepatitis C-treated patients
Recomendaciones técnicas para mejorar la seguridad sísmica de viviendas de albañilería confinada de la costa peruana
En este proyecto se desarrolla una metodología simple para determinar el riesgo sísmico de viviendas informales de albañilería confinada. Para ello, se ha realizado un
estudio sobre los errores arquitectónicos, constructivos y estructurales de 270 viviendas
construidas informalmente en 5 ciudades de la costa del Perú.
Las viviendas informales son construidas por pobladores, albañiles y maestros de obra, sin asesoramiento técnico o profesional. Muchas veces las viviendas informales son
vulnerables ante los sismos y colapsan, causando innumerables pérdidas económicas y lamentables pérdidas de vida.
Para recolectar información sobre las construcciones informales se encuestaron un total
de 270 viviendas ubicadas en Chiclayo (30), Trujillo (30), Lima (150), Ica (30) y Arequipa (30). Las tareas de recolección de información en campo se realizaron en
fichas de encuesta por alumnos de la PUCP. Después la información recogida fue procesada en fichas de reporte donde se obtuvo la vulnerabilidad, peligro y riesgo
sísmico de las viviendas encuestadas. Luego, con la información obtenida se elaboró
una base de datos para clasificar los principales defectos de las viviendas analizadas.
Los resultados obtenidos contribuyeron al desarrollo de una cartilla para la
construcción y mantenimiento de viviendas de albañilería confinada en zonas de alto peligro sísmico. La cartilla presenta información sobre cada paso del proceso
constructivo en forma gráfica y con lenguaje muy simple. Se espera que, con una adecuada difusión, esta cartilla pueda servir para que los pobladores y albañiles
puedan conocer mejor cómo pueden construir viviendas sismorresistentes de
albañilería confinada.
Esta tesis está organizada en nueve capítulos y un apéndice distribuidos de la siguiente
forma:
En el Capítulo 1, “Introducción”, se plantea el problema de las viviendas informales de
albañilería de arcilla de la costa del Perú. Se describen los antecedentes de trabajo y se
explica la justificación de esta investigación. Además, se muestran las hipótesis
propuestas y los objetivos que se esperan cumplir.
En el Capítulo 2, “Marco teórico y metodología”, se presenta la relación que existe
entre el problema particular de estudio y las teorías e investigaciones similares
realizadas anteriormente. También, se presenta la metodología seguida y se explican los conceptos relacionados en el desarrollo de la investigación.
En el Capítulo 3, “Descripción de las zonas estudiadas”, se muestran las características
geográficas, demográficas y socio económicas de las zonas donde se han realizado
encuestas de viviendas informales.
En el Capítulo 4, “Fichas de encuesta y fichas de reporte”, se describen las fichas de encuesta y de reporte, y se explican detalladamente los cálculos para determinar el
riesgo sísmico de las viviendas de albañilería.
En el Capítulo 5, “Defectos de la construcción de las viviendas informales”, se
describen los problemas de ubicación, constructivos y estructurales más comunes de las viviendas autoconstruidas. También, se realiza un análisis de la calidad de mano de
obra en la construcción de las viviendas.
En el Capítulo 6, “Base de datos de los errores constructivos”, se presentan tablas de
conteo donde se han organizado estadísticamente los errores constructivos
encontrados en las viviendas informales.
En el Capítulo 7, “Construcción de viviendas”, se desarrolla un conjunto de
recomendaciones básicas para que el poblador pueda construir adecuadamente su
vivienda sismorresistente de albañilería.
En el Capítulo 8, “Reparación y reforzamiento de viviendas”, se presenta un conjunto
de recomendaciones básicas para la reparación y reforzamiento de viviendas
sismorresistentes de albañilería. Se espera que con estas recomendaciones el poblador sea capaz de realizar reparaciones y reforzamientos sencillos.
Finalmente, en el Capítulo 9, “Conclusiones y recomendaciones”, se escriben las
conclusiones del trabajo y se resumen los resultados de la investigación. Además, se
muestran las recomendaciones para futuras líneas de investigación sobre
vulnerabilidad de viviendas de albañilería.
El apéndice, “Cartilla de recomendaciones técnicas para la construcción y
mantenimiento de viviendas de albañilería”, contiene una cartilla gráfica que muestra cómo construir y reparar viviendas de albañilería confinada sismorresistente.Tesi
Construcción sismorresistente en tierra: la gran experiencia contemporánea de la Pontificia Universidad Católica del Perú
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