UPCommons - E-prints UPC Universitat Politècnica de Catalunya
E-prints UPC cobreix dues finalitats: per una banda, és el dipòsit institucional de la UPC que recull els articles de revista, les comunicacions de congrés i els reports de recerca generats en les activitats de recerca del personal docent i investigador de la universitat; per l'altra, és una eina que permet accelerar la producció científica, allotjant versions de documents prèvies a la publicació en una revista o a les actes d’un congrés.
Articles de revista
Mostrando recursos 1 - 20 de 161
Evolution of pyrrhotite oxidation in aggregates for concrete - Oliveira da Silva, Izelman; Pialarissi Cavalaro, Sergio Henrique; Aguado de Cea, Antonio
Rocks containing pyrrhotite bands are sometimes used to produce concrete. These rocks oxidize and produce long-term expansive reactions that damage concrete structures, leading to important economic and risk related repercussions. The present study analyses several aspects that affect the oxidation process of the aggregate such as the existence of preferential paths for the entrance of the oxidizing agent and the conversion process of the chemical elements involved in the reaction. For that, host rock samples containing pyrrhotite were investigated by scanning electron microscopy and energy dispersive spectroscopy. The results shows that the pyrrhotite appears in bands that create planes of...
Vigas armadas híbridas de acero: estado del conocimiento - Chacón Flores, Rolando Antonio
Una viga armada se considera híbrida cuando se utilizan diferentes límites elásticos de acero en las chapas de alas y alma que la conforman. Un diseño estructural de una viga armada híbrida puede resultar más eficiente que el de una viga homogénea, tanto desde un punto de vista resistente como desde un punto de vista económico y sostenible. Para una capacidad a flexión dada, se utilizarán chapas de acero de viga armada de menor espesor que su equivalente de viga homogénea. Las vigas armadas híbridas han sido estudiadas a nivel teórico, experimental y numérico bajo solicitaciones de flexión, de inestabilidad...
Nonlinear analysis of RC beams using a hybrid shear-flexural fibre beam model - Santos Ferreira, Denise Carina; Bairán García, Jesús Miguel; Marí Bernat, Antonio Ricardo; Faria, Rui
Purpose: A nonlinear finite element (FE) beam-column model for the analysis of reinforced concrete (RC) frames with due account of shear is presented in this paper. The model is an expansion of the traditional flexural fibre beam formulations to cases where multiaxial behaviour exists, being an alternative to plane and solid FE models for the nonlinear analysis of entire frame structures. The paper aims to discuss these issues.
Design/methodology/approach: Shear is taken into account at different levels of the numerical model: at the material level RC is simulated through a smeared cracked approach with rotating cracks; at the fibre level, an...
A breakdown of energy consumption in an underground station - Casals Casanova, Miquel; Gangolells Solanellas, Marta; Forcada Matheu, Núria; Macarulla Martí, Marcel; Giretti, Alberto
Underground transportation systems are big energy consumers and have significant impacts on energy consumption at a regional scale. The literature has revealed that the energy consumption for non-traction purposes may be of the same magnitude as the energy used to move rolling stock, and in some cases even greater. However, most of the research conducted so far has focused on the energy demand of rolling stock. This paper investigates the electricity consumption of an underground metro station using data from on-site surveys and measurements. With an average consumption of 217.64 kWh/m(2)/year, the breakdown revealed that the lighting system dominated the...
Improvement of the durability of concrete with recycled aggregates in chloride exposed environment - Vázquez Ramonich, Enric; Barra Bizinotto, Marilda; Aponte Hernández, Diego Fernando; Valls del Barrio, Susanna; Jiménez, Cristian
Recycled aggregates concrete (RAC) becomes an important participant in recycled materials although there are still questionable properties of it, like chloride penetration and diffusion. An extensive experimental campaign was performed in order to evaluate the effect of recycled concrete aggregates (RCA) over some properties of concretes. Composition and mix design influence on the concrete were studied in mixes ranging from 0.45 to 0.60 w/c ratios, with 0%, 20%, 50% and 100% coarse aggregates replacement. Concretes were submitted to saline attack and the total chloride contents were determined as well as the chloride penetration profiles. Both new cement paste and RCA...
Estudio sísmico de los edificios agregados de obra de fábrica utilizando el método del espectro de capacidad - Moreno González, Rosangel; Bairán García, Jesús Miguel
Se presenta un estudio sobre el comportamiento sísmico de un conjunto de edificios agregados de obra de fábrica situados en la ciudad de Barcelona, España. Considerando la edad que tienen estos edificios (más de 70 años) se definen dos propiedades mecánicas para la mampostería. La acción sísmica considerada se define a partir del espectro elástico de respuesta definido en el Eurocódigo 8 para la aceleración sísmica de Barcelona. Para analizar los edificios se utiliza el método del espectro de capacidad, a partir del cual se obtienen la curva de capacidad y las curvas de fragilidad para evaluar el daño sísmico...
Comparación de resultados obtenidos en el proyecto de estructuras de hormigón aplicando la Instrucción EHE-08 y el Eurocódigo 2 - Marí Bernat, Antonio Ricardo; Oller Ibars, Eva; Bairán García, Jesús Miguel; Duarte Gómez, Noemí; Cladera Bohigas, Antoni
La Instrucción Española de Hormigón Estructural EHE-08 fue el resultado de una profunda revisión de la anterior Instrucción EHE-98, sobre la que se realizaron numerosas modificaciones orientadas a adaptar la Instrucción al actual marco normativo europeo y al actual estado del conocimiento, promover la mejora de la calidad de las obras sin sobrecostes injustificados y contribuir al desarrollo sostenible. En dicho contexto, se realizó un trabajo orientado a comparar los resultados de aplicar la Instrucción EHE-08 y el Eurocódigo EC-2 al proyecto de diferentes estructuras. Se estudiaron seis tipos estructurales, que se consideran representativos de las obras de hormigón estructural...
Assessment of the fibre orientation factor in SFRC slabs - Blanco Álvarez, Ana; Pujadas Álvarez, Pablo; Fuente Antequera, Albert de la; Pialarissi Cavalaro, Sergio Henrique; Aguado de Cea, Antonio
The design of steel fibre reinforced concrete (SFRC) structures is evolving towards a new approach that uses correction factors to consider differences between the small-scale characterization specimens and the real-scale elements. Recently, the Model Code 2010 proposed an orientation factor (K) that accounts for the effects of the orientation in the structural response of elements. The present study focuses on the identification of this factor in SFRC slabs with different dimensions. For that, flexural tests on real-scale slabs were conducted and the fibre orientation was assessed with an inductive method. A finite element analysis showed the differences between the experimental...
Methodology for the design of controlled low-strength materials: application to the backfill of narrow trenches - Blanco Álvarez, Ana; Pujadas Álvarez, Pablo; Pialarissi Cavalaro, Sergio Henrique; Aguado de Cea, Antonio
The design of controlled low-strength materials (CLSM) is generally based on experimental approaches without considering an efficient use of the component materials. The present study proposes a general methodology for the design of optimised CLSM that includes the definition of the mechanical requirements through numerical simulations with FEM and an experimental procedure to define the mix by optimising the aggregate skeleton, the content of cement and the use of admixtures and additions. Moreover, the methodology is applied to the backfill of narrow trenches.
Study of the recycled aggregates nature's influence on the aggregate-cement paste interface and ITZ - Sidorova, Anna; Vázquez Ramonich, Enric; Barra Bizinotto, Marilda; Roa Rovira, Joan Josep; Jiménez Piqué, Emilio
Today it is highly recognized that the structure of the cement paste matrix close to the aggregates, is different from the rest of the cement paste. This investigation compares the possible interfacial transition zone (ITZ) formation by means of the nanoindentation test and Scanning Electron Microscopy (SEM), with aggregate inclusions of three different natures: limestone (NA), recycled concrete aggregate (RCA) and recycled ceramic aggregate (RC). This study demonstrated that nature of the aggregate and the w/c ratio conditions determines the micro structural characteristics of the aggregate–cement paste interface and the mechanical properties of the ITZ.
Constitutive model for fibre reinforced concrete based on the Barcelona test - Blanco Álvarez, Ana; Pujadas Álvarez, Pablo; Pialarissi Cavalaro, Sergio Henrique; Fuente Antequera, Albert de la; Aguado de Cea, Antonio
Several constitutive models for fibre reinforced concrete (FRC) have been reported in the past years based on the flexural performance obtained in a bending test. The Barcelona test was presented as an alternative to characterise the tensile properties of FRC; however, no constitutive model was derived from it. In this article, a formulation to predict the tensile behaviour of FRC is developed based on the results of the Barcelona test. The constitutive model proposed is validated by simulating the results of an experimental program involving different types of fibres and fibre contents by means of finite element software. More-over, the...
Plastic fibres as the only reinforcement for flat suspended slabs: Parametric study and design considerations - Pujadas Álvarez, Pablo; Blanco Álvarez, Ana; Pialarissi Cavalaro, Sergio Henrique; Aguado de Cea, Antonio; Grünewald, Steffen; Blom, CBM; Walraven, Joost C
The use of constitutive equations from the standards to model flat suspended slabs reinforced only with plastic fibres leads to an overestimation of the experimental response of these elements. To address such problem, a parametric study is conducted. In this study, the influence of the parameters from the constitutive equations on the structural behaviour of the slabs is analysed and the ones that provide the best fit with the experimental results are found through a non-linear regression. Based on this analysis, the existence of a network effect was identified and a design philosophy for suspended slabs reinforced only with
Fibre distribution in macro-plastic fibre reinforced concrete slab-panels - Pujadas Álvarez, Pablo; Blanco Álvarez, Ana; Pialarissi Cavalaro, Sergio Henrique; Fuente Antequera, Albert de la; Aguado de Cea, Antonio
This paper focuses on the study of the influence of flowability and wall-effects of the formwork in the orientation pattern of macro-plastic fibres. In order to identify the preferential orientation of fibres caused by the geometry of slabs, pairs of specimens drilled from PFRC slabs with different width/length – ratio are tested using the multidirectional double punch test (MDPT). The results show that plastic fibres tend to be oriented parallel to the walls or surfaces of the formwork and perpendicular to the flow direction for a free surface flow. The side walls slightly redistribute the fibre orientation, as the transverse...
Deep enclosures versus pumping to reduce settlements during shaft excavations - Pujades Garnes, Estanislao; Vázquez Suñé, Enric; Carrera Ramírez, Jesús; Vilarrasa Riaño, Victor; Simone, Silvia de; Jurado Elices, Anna; Ledesma Villalba, Alberto; Ramos Schneider, Gonzalo; Lloret Morancho, Antonio
Deep excavations in aquifers may be constructed by combining pumping with the cut and cover method. The enclosures are often deepened more than structurally needed, in order to diminish the risk of heave or fluidisation inside the excavation, and to reduce pumping rates and the associated settlements outside jet-grouting piles are sometimes adopted for lengthening. We analysed the water-proofing efficiency of jet-grouting and the need for water isolation in preconsolidated sediments. We used data obtained from two shaft excavations during the construction of the high speed train tunnel in Barcelona, located adjacent to the Sagrada Familia Basilica. Jet-grouting was characterised...
Development of a low pH cementitious material to enlarge bioreceptivity - Manso Blanco, Sandra; Mestres Beà, Gemma; Ginebra Molins, Maria Pau; de Belie, Nele; Segura Pérez, Ignacio; Aguado de Cea, Antonio
This paper presents a laboratory investigation into the development of a low-pH cementitious material in order to enlarge bioreceptivity. Two different options were tested; reduction of Ordinary Portland Cement (OPC) pH and assessment of the suitability of another hydraulic binder with lower pH, Magnesium-Phosphate Cement (MPC). Regarding OPC, additions of acidic compounds such as boric acid and oxalic acid were investigated. Furthermore, an in-depth characterization of MPC was carried out to evaluate its suitability as a binder for concrete. For this purpose, physico-chemical as well as mechanical properties were tested.
Multidirectional double punch test to assess the post-cracking behaviour and fibre orientation of FRC - Pujadas Álvarez, Pablo; Blanco Álvarez, Ana; Pialarissi Cavalaro, Sergio Henrique; Fuente Antequera, Albert de la; Aguado de Cea, Antonio
The wide variety of tests currently used for the characterization of fibre reinforced concrete (FRC) only allow a unidirectional characterization (without considering the orientation of the fibres in the matrix). However, from a design-oriented perspective, the anisotropy due to the dispersion and orientation of
fibres has to be taken into account when characterizing the mechanical behaviour of the material. In this paper, an alternative to the conventional tests applied for the characterization of FRC is proposed. The multidirectional double punch test (MDPT) consists of a double punch test applied to a cubic specimen. Due to the specimen shape in a single...
Bioreceptivity evaluation of cementitious materials designed to stimulate biological growth - Manso Blanco, Sandra; De Muynck, Willem; Segura Pérez, Ignacio; Aguado de Cea, Antonio; Steppe, Kathy; Boon, Nico; de Belie, Nele
Ordinary Portland cement (OPC), the most used binder in construction, presents some disadvantages in terms of pollution (CO2 emissions) and visual impact. For this reason, green roofs and façades have gain considerable attention in the last decade as a way to integrate nature in cities. These systems, however, suffer from high initial and maintenance costs. An alternative strategy to obtain green facades is the direct natural colonisation of the cementitious construction materials constituting the wall, a phenomenon governed by the bioreceptivity of such material.
This work aims at assessing the suitability of magnesium phosphate cement (MPC) materials to allow a rapid...
Alternative methodology to consider damage and expansions in external sulfate attack modeling - Ikumi Montserrat, Tai; Pialarissi Cavalaro, Sergio Henrique; Segura Pérez, Ignacio; Aguado de Cea, Antonio
A diffusion–reaction numerical model is proposed to simulate the response of concrete exposed to external sulfate attack. Diffusion properties are modified based on the strain reached and the ratio of porosity filled by ettringite. A direct and intuitive approach is proposed for the consideration of the diffusion in a cracked porous media based on the constitutive law of the material. A methodology to compute expansions based on a more realistic consideration of the concrete porosimetry is presented, by which it is possible to distinguish different strain contributions from different pore sizes. The described approach also allows the consideration of different...
Durability of recycled aggregate concrete designed with the Equivalent Mortar Volume (EMV) method: Validation under the Spanish context and its adaptation to Bolomey methodology - Jiménez Fernández, Cristian Gonzalo; Barra Bizinotto, Marilda; Valls del Barrio, Susanna; Aponte Hernández, Diego Fernando; Vázquez Ramonich, Enric
Some durability properties are analyzed in concretes made with a novel method for recycled aggregates concrete (RAC) proportioning, in order to validate it under the Spanish context. Two types of concrete mixes were elaborated; one following the guidelines of the named method, and other based on an adaptation of the method to Bolomey methodology. Two types of recycled concrete aggregates (RCA) were used. RCA replacement for natural aggregates (NA) ranged from 20% to 100%. The 20% was chosen in order to comply with Spanish recommendations. Water penetration under pressure, water absorption and chlorides attack were the studied properties. It is...
Thermo-mechanical simulation of the ConCrack Benchmark RL1 test with a filament beam model - Santos Ferreira, Denise Carina; Crespo, María Delia; Marí Bernat, Antonio Ricardo; Bairán García, Jesús Miguel
Cracking is an inherent characteristic of RC structural behaviour and its control is an important concern for durability and sustainability. The French national research program CEOS.fr –‘Behaviour and assessment of special construction works concerning cracking and shrinkage’– has carried out an experimental campaign focused on cracking behaviour. An international benchmark (ConCrack) was organized with the goal of achieving a state of the art on cracking modelling of concrete structures. In this paper, the blind prediction of the RL1 test –large RC beam specimen loaded in bending after free shrinkage– by means of a thermo-mechanical filament beam model is presented. Numerical...