36 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
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
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
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
Construcción sismorresistente en tierra: la gran experiencia contemporánea de la Pontificia Universidad Católica del Perú
In many developing countries the most common alternative for dwelling construction is building with earth because the material is abundant and cheap. The quality of most traditional earthen construction is very low, because it is done informally, with little or no technical assistance. In seismic areas where earthen construction is common, every time an earthquake occurs, many dwellings collapse, causing considerable economic losses and tragic injuries and deaths. The professional and academic communities in some seismic countries have not remained indifferent to this important problem. Researchers at the Catholic University of Peru (PUCP) have been investigating on the construction of earthen buildings in seismic areas for about 40 years and have obtained invaluable results.
This article describes the evolution of the knowledge generated at PUCP of reinforced earth, a material composed of earth and compatible reinforcements, with which it is possible to build seismic-resistant constructions.En muchos países en vías de desarrollo la alternativa de vivienda más común es la construcción con tierra, pues el material es abundante y barato. La construcción tradicional de viviendas de tierra se realiza informalmente, sin asesoría técnica. Por ello, la calidad de estas construcciones es generalmente muy baja. En zonas sísmicas donde se construye con tierra, cada vez que ocurre un terremoto colapsan muchas construcciones de este material, causando considerables pérdidas económicas y lamentables pérdidas de vidas. Las comunidades académicas y profesionales de algunos países sísmicos no han permanecido impasibles frente a esta grave situación. En el Perú, investigadores de la Pontificia Universidad Católica del Perú (PUCP) han venido investigando la construcción con tierra en áreas sísmicas desde hace cerca 40 años y han obtenido invalorables resultados.
Este artículo describe la evolución del conocimiento generado en la PUCP del material tierra armada, compuesto por tierra y refuerzos compatibles, que permite lograr construcciones sismorresistentes
Scenario-based multi-risk assessment from existing single-hazard vulnerability models. An application to consecutive earthquakes and tsunamis in Lima, Peru
Multi-hazard risk assessments for building portfolios
exposed to earthquake shaking followed by a tsunami are usually based on
empirical vulnerability models calibrated on post-event surveys of damaged
buildings. The applicability of these models cannot easily be extrapolated
to other regions of larger/smaller events. Moreover, the quantitative
evaluation of the damages related to each of the hazard types
(disaggregation) is impossible. To investigate cumulative damage on extended building portfolios, this study proposes an alternative and modular method to probabilistically integrate sets of single-hazard vulnerability models
that are constantly being developed and calibrated by experts from various
research fields to be used within a multi-risk context. This method is based
on the proposal of state-dependent fragility functions for the triggered
hazard to account for the pre-existing damage and the harmonisation of
building classes and damage states through their taxonomic characterisation, which is transversal to any hazard-dependent vulnerability. This modular assemblage also allows us to separate the economic losses expected for each scenario on building portfolios subjected to cascading hazards. We
demonstrate its application by assessing the economic losses expected for
the residential building stock of Lima, Peru, a megacity commonly exposed to
consecutive earthquake and tsunami scenarios. We show the importance of
accounting for damage accumulation on extended building portfolios while
observing a dependency between the earthquake magnitude and the direct
economic losses derived for each hazard scenario. For the commonly exposed
residential building stock of Lima exposed to both perils, we find that
classical tsunami empirical fragility functions lead to underestimations of predicted losses for lower magnitudes (Mw) and large overestimations for larger Mw events in comparison to our state-dependent models and cumulative-damage method.</p