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UPCommons - E-prints UPC Universitat Politècnica de Catalunya (67,896 recursos)
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 151

1. 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...

2. 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 plastic fibres...

3. 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...

4. 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...

5. 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.

6. 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...

7. 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...

8. 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...

9. 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...

10. 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...

11. The latent causes of rework in floating production storage and offloading projects - Love, Peter E.D.; Edwards, David J.; Irani, Zahir; Forcada Matheu, Núria
There is growing demand for cost effective and reliable floating production systems to maximize marginal and new deepwater fields worldwide. Floating Production Storage and Offloading (FPSO) vessels are considered to be the most economical and viable options to meet this demand. Yet, FPSO projects are prone to significant cost and schedule growth. On average, FPSOs have been reported to experience a 20% cost growth and are delayed by six months. Overruns and delays represent uncertainties for owners, contractors and financial institutions. In-depth interviews with twenty-three practitioners about their experiences with FPSO projects revealed that rework arising from design and construction...

12. A localized mapped damage model for orthotropic materials - Pelà, Luca; Cervera Ruiz, Miguel; Oller Martínez, Sergio Horacio; Chiumenti, Michèle
This paper presents an implicit orthotropic model based on the Continuum Damage Mechanics isotropic models. A mapping relationship is established between the behaviour of the anisotropic material and that of an isotropic one. The proposed model is used to simulate the failure loci of common orthotropic materials, such as masonry, fibre-reinforced composites and wood. The damage model is combined with a crack-tracking technique to reproduce the propagation of localized cracks in the discrete FE problem. The proposed numerical model is used to simulate the mixed mode fracture in masonry members with different orientations of the brick layers.

13. Occupational risk index for assessment of risk in construction work by activity - Casanovas Rubio, Maria del Mar; Armengou, Jaume; Ramos Schneider, Gonzalo
The concern for occupational health and safety in construction work is reflected in the many preventive measures taken. However, examples of the systematic assessment of project alternatives aimed at minimizing occupational hazards are rare. This paper proposes a measure of occupational safety [occupational risk index (ORI)] that is based solely on the project design and resulting construction process, and is a function of the activities carried out and their specific occupational risk (probability and consequences of occurrence). The ORI can thus be used as an indicator to feed multicriteria decision-analysis tools. The proposal is illustrated with a simple example in...

14. The production of construction and demolition waste material and the use of recycled aggregates in Havana, Cuba - Pavón, Elier; Etxeberria Larrañaga, Miren; Martinez, Ivan
En este trabajo se realiza un análisis de la generación de Residuos Sólidos Urbanos (RSU) y de Residuos de Construcción y Demolición (RCD) para el período de 1999 a 2010 en la Habana Cuba, y se define su posible uso en la fabricación de áridos reciclados para la producción de mortero y hormigón. Para la definición de las posibles aplicaciones de los RCD como agregados en la producción de mortero y hormigón, se decidió comenzar por el análisis de las características de los residuos, así como el estudio de las tecnologías actuales disponibles en la provincia para su tratamiento. Basándose...

15. Standardizing housing defects: classification, validation and benefits - Macarulla Martí, Marcel; Forcada Matheu, Núria; Casals Casanova, Miquel; Gangolells Solanellas, Marta; Fuertes Casals, Alba; Roca Ramon, Xavier
Defects produce economic and temporal deviations in construction projects. Although learning from past experiences can help reduce defects and their consequences, usually data is not easily available, or is poorly structured and difficult to analyze. Several structured classification systems for defects exist, but regionally specific construction activities make the data unviable for research use. This paper presents the development and the validation of a defects' classification system for the Spanish housing sector. From the analysis of the existing defect classification systems, a first draft was developed to be discussed and improved in a series of workshops done by a panel...

16. Estudio sísmico de los edificios agregados de obra de fábrica utilizando el método del espectro de capacidad - Moreno González, Rosángel; 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 esperado....

17. An X-ray photoelectron spectroscopy study of the hydration of C2S thin films - Rheinheimer, Vanessa; Casanova Hormaechea, Ignasi
Electron-beam evaporation was used to produce thin films of ß-dicalcium silicate. Chemical and mineralogical compositions were characterized by X-ray photoelectron spectroscopy (XPS) and grazing-angle X-ray diffraction (GAXRD), respectively. Results showthat no fractionation occurs during evaporation and isostructural condensation of the material as synthesized films have the same composition as the initial bulk material. Samples were gradually hydrated under saturatedwater spray conditions and analyzed with XPS. Polymerization of the silicate chains due to hydration, and subsequent formation of C-S-H, has been monitored through evaluation of energy shifts on characteristic silicon peaks. Quantitative analyses show changes on the surface by the reduction...

18. Assessment of prestressed concrete bridge girders with low shear reinforcement by means of a non-linear filament frame model - Santos Ferreira, Denise Carina; Marí Bernat, Antonio Ricardo; Bairán García, Jesús Miguel
The safety of existing bridges and the efficiency of strengthening measures can be accurately studied through non-linear numerical models, assisting decisions of dismantle, repair or change of use and avoiding unnecessary or inappropriate interventions. In this ambit, filament beam models due to their inherent simplicity and low computational demand are adequate for the engineering practice. Accordingly, in this paper, the structural assessment of a prestressed concrete bridge presenting low shear reinforcement, the Wassnerwald Viaduct in Switzerland, is presented. The bridge was dismantled due to, among other reasons, not complying with the safety standards related to shear. The girders of the...

19. Plastic fibres as the only reinforcement for flat suspended slabs: Experimental investigation and numerical simulation - Pujadas Álvarez, Pablo; Blanco Álvarez, Ana; Pialarissi Cavalaro, Sergio Henrique; Aguado de Cea, Antonio
This paper focuses on the study of the structural response of hyperstatic concrete flat suspended slabs reinforced only with structural plastic macro-fibres. First, the experimental program is described and then the results obtained are presented. The slabs tested maintained a high load level after cracking showing a ductile behaviour with great stress redistribution capacity. Next, the tests were simulated by means of a finite element software with constitutive models according to the specifications of RILEM and the Spanish Structural Concrete Code (EHE). The numerical results in terms of load/mid-span deflection were compared with the experimental results. The predictions provided by...

20. Collapse of a precast concrete beam for a light roof: importance of elastomeric bearing pads in the element’s stability - Bairán García, Jesús Miguel; Cladera Bohigas, Antoni
The importance of second order effects has been widely studied in slender concrete structures subjected to compressive stresses, although their effects are not generally taken into account in other fields of structural engineering; this is the case of the overall stability of structures flexible supports, as elastomeric bearing pads. In this paper, the collapse in construction of a 24.9 m span precast concrete Y-beam for the light roof of a sports hall is studied. The roof consisted of a series of these beams simply supported at each end by plain neoprene bearing pads. After a worker had climbed up to...

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