201 research outputs found
A Simple Method for Calculating the Shear Deformation of Reinforced Concrete Elements in the Elastic and Plastic Domains
This paper proposes a simple method for calculating the shear deformation and the shear capacity of reinforced and prestressed
concrete elements containing shear reinforcement. This new approach considers that, for large deformations, concrete
elements follow compatibility conditions based on displacements of the composite material subjected to shearing forces. The
result is a beam, inspired by the Timoshenko-Ehrenfest beam theory, which considers a new hypothesis regarding shearing
deformation, informed by the behavior of the shear reinforcement. The new method is compared with previous approaches,
allowing us to assess the technological advances of the new proposal. The new method is easy to implement and provides
information about the shearing deformation (in the elastic and plastic domains) and the shearing capacity of concrete beamcolumn
elements. A detailed example is developed, in which all the components of the shear deformation are evaluated, and
the simplification of the new method is analyzed in comparison with other more comprehensive methods in the elastic domainUniversidad de Granada/
CBU
Fragility Curves for Historical Structures with Degradation Factors Obtained from 3D Photogrammetry
The influence of the effects of the degradation of materials on the seismic fragility of
Cultural Heritage buildings in Granada (Spain) is investigated. The degradation of the material,
which mainly happens at the lower levels of the façades, is obtained by using 3D photogrammetry
data. Fragility curves for three cultural heritage constructions in Granada are calculated by using
FE nonlinear dynamic analyses for both non-deteriorated and deteriorated geometries. The Finite
Elements (FE) models, based on the macro-modelling technique, are subjected to ground motions
for the city of Granada, which were selected by considering Probabilistic Seismic Hazard Analysis
(PSHA) methodology with their probability of occurrence. The response of each model is analyzed for
different seismic Intensity Measure (IM) levels, which, in this study, correspond to average pseudoacceleration.
The procedure is applied to three monuments in Granada that were built with two
different constructions materials: calcarenite and rammed earth. The damage mechanisms considered
are roof displacement or maximum compressive principal stress, depending on each case. The results
show that the restoration works that have been carried out has prevented structural failures in the
rammed earth construction studied, and that, during future seismic events, special attention must
be paid to the level of compressive strengh reached in the Santa Pudia calcarenite used at the San
Jerónimo monastery.European Union's Framework Programme for Research and Innovation (Horizon 2020)Spanish Government (Ministerio de Ciencia, Innovacion y Universidades) as part of the Research Projects 821054RTI2018-101841-B-C21
RTI2018-101841-B-C2
Mechanical characterization and elastic stiffness degradation of unstabilized rammed earth
Rammed earth is attracting renewed interest due to its sustainability. In this work, a mechanical
characterization of unstabilized rammed earth is presented. Compressive strength, Young’s
modulus, and Poisson’s ratio were determined, with the first of these being the most representative
mechanical property of rammed earth. Stress – strain curves were obtained from uniaxial
compression tests. Creep is of great importance in the long-term assessment of historical buildings
and in the design of new ones. Samples of rammed earth were subjected to a constant load for 15
days to study their creep behavior. In order to simulate the long-term behavior of the material,
different rheological models were fitted to the experimental results. The instantaneous deformation
of rammed earth samples caused by a sudden additional load (maintaining a previous
service load level) was also studied. This is the first time that this phenomenon, called elastic
stiffness degradation, has been studied for rammed earth material.European Union Framework Programme for Research and Innovation 82105
Influence of the level of connectivity on the members of the Octahedron and X-Octahedron families of tensegrities
Tensegrity structures based on topological patterns have been developed greatly in recent years. Tensegrities obtained from the same pattern are said to belong to a family. Two examples of tensegrity families are the Octahedron and the X-Octahedron, whose members are composed of rhombic and X-rhombic cells, respectively, which are collected in three groups. The general connectivity pattern of both families consists of three levels of connectivity. This work analyzes the influence of the reduction of the level of connectivity on the members of both families. The connection graphs corresponding to different levels of connectivity are defined based on the new concept of “twin tensegrities”. Analytical computations have been performed to determine the force:length ratios that satisfy equilibrium, stability, and super-stability conditions. In addition, the mathematical sequence that follows the ratio between the force:length ratio of struts and cables of the X-Octahedron family that leads to a super-stable equilibrium configuration is presented. The new tensegrities obtained in this work also belong to the Octahedron and X-Octahedron families and could have promising engineering applications such as modular constructions.Funding for open access charge: Universidad de Málaga / CBU
Molecular and structural considerations of TF-DNA binding for the generation of biologically meaningful and accurate phylogenetic footprinting analysis: the LysR-type transcriptional regulator family as a study model
Bayesian assessment of surface recession patterns in brick buildings with critical factors identification
The deterioration of built heritage is a major concern for many countries. In the specific caseof brick heritage buildings, degradation depends on several factors such as the chemical andmineralogical composition and the porosity of the bricks, floor insulation and exposure toenvironmental conditions. This paper applies a probabilistic Bayesian approach to identi-fying the pattern of recession of the brick walls using digital photogrammetry data. Twocases studies are presented corresponding to two buildings classified as Assets of CulturalInterest by the Spanish Ministry of Culture. The analysis of physico-chemical factors andphotogrammetric descriptions allow a holistic understanding of the deterioration processto be developed. The degradation patterns and degradation velocities obtained are used forthe structural assessment of the buildings. The comparison of the degradation patterns ofboth buildings considering their individual features allows the most critical factors in thedegradation process of brick walls to be identified.El deterioro del patrimonio construido es una gran preocupación para muchos países. En el caso específico de los edificios patrimoniales de ladrillo, la degradación depende de varios factores como la composición química y mineralógica y la porosidad de los ladrillos, el aislamiento del suelo y la exposición a las condiciones ambientales. Este artículo aplica un enfoque probabilístico bayesiano para identificar el patrón de recesión de las paredes de ladrillo utilizando datos de fotogrametría digital. Se presentan dos casos de estudio correspondientes a dos edificios catalogados como Bienes de Interés Cultural por el Ministerio de Cultura español. El análisis de los factores físico-químicos y las descripciones fotogramétricas permiten desarrollar una comprensión holística del proceso de deterioro. Los patrones de degradación y las velocidades de degradación obtenidos se utilizan para la evaluación
estructural de los edificios. La comparación de los patrones de degradación de ambos edificios
considerando sus características individuales permite identificar los factores más
críticos en el proceso de degradación de las paredes de ladrillo.Spanish Government RTI2018-101841-B-C21
RTI2018-101841-B-C2
Designing compression structures by topological mapping
Congreso celebrado en la Escuela de Arquitectura de la Universidad de Sevilla desde el 24 hasta el 26 de junio de 2015.The Force Density Method has been traditionally employed to seek the equilibrium shape of tension structures. Recently, the use of a process based on topology has been introduced to provide a first network in which the Force Density Method can be applied. Compression-only structures such as vaults and domes can also be modelled by means of the former approach if this is modified to get a design process similar to the Gaudí’s one based on hanging models. The conjunction of Topological Mapping and the Forced Density Method is first explained in the form-finding process of tension structures and, later on, the modifications to that approach are introduced so that an iterative procedure is obtained to get equilibrium shapes of compression-only structures. The versatility of this novel approach is presented by means of the analysis of some representative examples
Mechanical characterization and elastic stiffness degradation of unstabilized rammed earth
Rammed earth is attracting renewed interest due to its sustainability. In this work, a mechanical
characterization of unstabilized rammed earth is presented. Compressive strength, Young’s
modulus, and Poisson’s ratio were determined, with the first of these being the most representative
mechanical property of rammed earth. Stress – strain curves were obtained from uniaxial
compression tests. Creep is of great importance in the long-term assessment of historical buildings
and in the design of new ones. Samples of rammed earth were subjected to a constant load for 15
days to study their creep behavior. In order to simulate the long-term behavior of the material,
different rheological models were fitted to the experimental results. The instantaneous deformation
of rammed earth samples caused by a sudden additional load (maintaining a previous
service load level) was also studied. This is the first time that this phenomenon, called elastic
stiffness degradation, has been studied for rammed earth material
An approximate procedure for a general analytical expression of the Prandtl membrane analogy in linear elastic pure torsion
Artículo en revisiónFor pure torsion in linear elasticity, if the shape of cross-section is defined by a closed-form analytical expression satisfying certain conditions, the shear stress in each of the principal Cartesian directions can be obtained by the derivation of the stress function, whose analytical expression can be obtained from the Prandtl analogy. In this paper, a general methodology to obtain an approximate analytical expression of the Prandtl membrane is presented. The proposed methodology uses two variable quadratic piecewise functions to define the Prandtl membrane. This approximate procedure can be applied to any cross-section shape, and it has been proved be especially suitable for steel shapes, for which the proposed method leads to values close to the ones obtained with more precise methods. Several examples are presented
Strength design optimization of structural steel members according to Eurocode3
In order to design a steel member subjected to a bending moment and an axial load, there are an infinite number of possible solutions of I- or H‐steel cross-sections, the doubly-symmetric solution being just one of them. This paper presents a procedure to obtain the optimal steel cross-section from the infinite number of possible solutions. The process is based on the Reinforcement Sizing Diagrams employed in reinforced concrete strength design. The procedure looks for any type of solution regarding compact or non-compact steel sections. All aspects related to local instabilities are taken into account, as well as some special considerations in order to address the global instabilities associated with the slenderness of the steel element.The present work was financed by the Spanish Ministry of Education. The first author is a Spanish Government PhD fellow (FPU grant AP 2010‐3707)
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