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  • Grup de tecnologies d'estructures

     Aguado De Cea, Antonio; Aparicio Bengoechea, Angel Carlos; Bairan Garcia, Jesus Miguel; Blanco Álvarez, Ana; Casas Rius, Joan Ramon; Chacon Flores, Rolando Antonio; de la Fuente Antequera, Alberto; Duarte Gomez, Noemi; Garcia Vicente, Tomas; Mirambell Arrizabalaga, Enrique; Molins Borrell, Climent; Oller Ibars, Eva; Pelà, Luca; Pialarissi Cavalaro, Sergio Henrique; Pujadas Alvarez, Pablo; Ramos Schneider, Gonzalo; Real Saladrigas, Esther; Roca Fabregat, Pedro; Santos Ferreira, Denise Carina; Segura Pérez, Ignacio; Turmo Coderque, Jose; Mari Bernat, Antonio Ricardo
    Competitive project

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  • Enginyeria de la construcció

     Molins Borrell, Climent
    Date of publication: 2014-02-01
    Book chapter

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  • Monolithic concrete off-shore floating sturcture for wind turbines

     Molins Borrell, Climent; Campos Hortigüela, Alexis; Sandner, Frank; Matha, Denis
    European Wind Energy Association¿s (EWEA) Annual Conference
    p. 107-111
    Presentation's date: 2014-03-12
    Presentation of work at congresses

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    A new concept of a SPAR floating platform is being developed in the KIC-Innoenergy project AFOSP (Alternative Floating Platform Designs for Offshore Wind Turbines using Low Cost Materials). Members of the consortium are Gas Natural Fenosa, University of Stuttgart and Universitat Politècnica de Catalunya. The main differentiating aspects with respect to other SPAR prototypes are the monolithic nature of the whole structure, including both, the platform and the tower, the use of post-tensioned concrete as main material and the installation process. A comparison between similar steel and concrete designs demonstrates that the material cost for the concrete structure is around one third of the steel one. Considering that the concrete Oil & Gas platforms are virtually free of maintenance and have an extended lifetime, the real cost is less than 1/3 of the steel one, while the offshore tasks and the moorings systems have similar costs for both alternatives. Following a hydrostatic pre-design of the structure, coupled aero-servo-hydro-elastic analyses for a 5MW wind turbine have been performed by using an in-house FOWT model with a reduced number of degrees of freedom (DOF) and simplified aero- and hydrodynamics. With the obtained loads, the most relevant structural members have been checked, including a simplified fatigue limit state analysis, obtaining a lifetime over 50 years. Finally, a comprehensive cost analysis has been performed to obtain the Levelized Cost Of Energy (LCOE) for the developed platform.

    A new concept of a SPAR floating platform is being developed in the KIC-Innoenergy project AFOSP (Alternative Floating Platform Designs for Offshore Wind Turbines using Low Cost Materials). Members of the consortium are Gas Natural Fenosa, University of Stuttgart and Universitat Politècnica de Catalunya. The main differentiating aspects with respect to other SPAR prototypes are the monolithic nature of the whole structure, including both, the platform and the tower, the use of post-tensioned concrete as main material and the installation process. A comparison between similar steel and concrete designs demonstrates that the material cost for the concrete structure is around one third of the steel one. Considering that the concrete Oil & Gas platforms are virtually free of maintenance and have an extended lifetime, the real cost is less than 1/3 of the steel one, while the offshore tasks and the moorings systems have similar costs for both alternatives. Following a hydrostatic pre-design of the structure, coupled aero-servo-hydro-elastic analyses for a 5MW wind turbine have been performed by using an in-house FOWT model with a reduced number of degrees of freedom (DOF) and simplified aero- and hydrodynamics. With the obtained loads, the most relevant structural members have been checked, including a simplified fatigue limit state analysis, obtaining a lifetime over 50 years. Finally, a comprehensive cost analysis has been performed to obtain the Levelized Cost Of Energy (LCOE) for the developed platform.

  • Numerical micro-modeling simulation of masonry in compression

     Drougkas, Anastasios; Roca Fabregat, Pedro; Molins Borrell, Climent
    International Masonry Conference
    p. 1-10
    Presentation's date: 2014-07-08
    Presentation of work at congresses

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    Micro-modeling techniques for the simulation of masonry are a valuable tool, when combined with nonlinear constitutive laws, for the investigation of the behavior of structural masonry. Through the simulation of the behavior of the materials locally up to and beyond failure, it is possible to evaluate the global behavior of the structure under a variety of loads. While the strength of the masonry joints and the unit-mortar interface in tension and shear can be fairly easily described in terms of frictional and tensile strength parameters, the compressive strength of the joints, and by extension the masonry composite, are more difficult to estimate a priori. For this reason, in the present paper a detailed micro-modeling approach in which units, mortar and their interface are modeled as separate parts, is proposed for the estimation of the compressive strength and the Young¿s modulus of the masonry composite. The approach proposed is based on well-known material and geometrical models. In addition, an analytical model for the estimation of the strength and the Young¿s modulus of masonry is also presented. A number of experimental case studies of masonry in compression reproduced using micro-modeling techniques are presented. The group of simulated cases consists of solid clay bricks and lime/cement mortar arranged in stack and running bond. A satisfactory comparison is obtained between the experimental values and the predictions of the FE and numerical micro-modeling methods proposed.

  • Masonry material characterization methodology for micro-modeling

     Drougkas, Anastasios; Roca Fabregat, Pedro; Molins Borrell, Climent; Alegre Heitzmann, Vicente
    International Masonry Conference
    p. 1-7
    Presentation's date: 2014-07-08
    Presentation of work at congresses

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    Numerical and analytical micro-modeling of masonry structures requires knowledge of several elasticity and strength parameters of the constituent materials of the composite. Furthermore, when dealing with specimens produced in the lab or extracted from existing structures, several problems arise concerning the limited number of samples and to their dimension ratios which will often render them inappropriate for accurate standardized testing. In the case of historical structures, the number of samples may be limited due to the need for compliance with conservation principles. This paper proposes a methodology for the experimental derivation of several material parameters of the units, the mortar and the masonry composite from a limited amount of sampled material using conventional mechanical tests. The method attempts to alleviate some of the obstacles often encountered in the experimental characterization of masonry structures, and focuses on those parameters that are most important for the simulation of masonry under compression using micro-modeling techniques. The applicability of the proposed methodology in actual existing structures is demonstrated through a case study.

  • Método de doble punzonamiento de tracción indirecta para concreto reforzado con fibra: Ensayo Barcelona

     Aire, Carlos; Aguado De Cea, Antonio; Molins Borrell, Climent
    Date of publication: 2013-12-10
    Book

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    The present work describes the results of an experimental investigation on the performances of concrete specimens reinforced with steel fibers using the double punch test (DPT). The DPT is an indirect tensile test based on the configuration of double-punch test, named, Barcelona test that was developed for the systematic control of fiber reinforced concrete. DPT can be carried out by testing 150 × 150 mm concrete cylinders subjected to double punching test. Previous experimental results have showed that DPT gives significantly lower variability compared to other test methods. In the test performed, indirect tensile strength and fracture toughness result obtained by DPT were compared using molded cylinder and core concrete specimens.

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    Ensayo de doble punzonamiento para concreto reforzado con fibra: efecto del tamaño y origen de la probeta  Open access

     Aire, Carlos; Molins Borrell, Climent; Aguado De Cea, Antonio
    Concreto y cemento: investigación y desarrollo
    Vol. 5, num. 1, p. 17-31
    Date of publication: 2013
    Journal article

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    Traditionally, to characterize the behavior of reinforced concrete with fiber (CRF) flexural tests are performed on beams. However, in accordance with various studies on FRC, it has been seen different variation coefficients of the order of 20 % for the results of flexural test beams. Recently, it has been developed a new method based on the double punching, called Barcelona test, as an alternative to determine the resistance to the indirect traction of the FRC. It is a test of easy execution over which a cylinder of 150 mm of diameter and 150 mm of height, undergoes double punching test, which allows to obtain the resistance to indirect tension of the FRC, with coefficients of variation less than those obtained by methods which employ beams. This article shows the results of a comparative study between results of resistance and toughness applying the Barcelona test obtained in molded test cylinders of 100 and 150 mm and cores of 93 and 153 mm.

  • Comportamiento resistente de revestimientos de túnel de anillos de dovelas prefabricadas de hormigón

     Arnau Delgado, Oriol; Molins Borrell, Climent
    Revista de obras públicas
    Vol. 160, num. 3546, p. 7-20
    Date of publication: 2013
    Journal article

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    This article presents the results of research carried out in the field of the structural response of tunnel linings made of precast concrete segments. The investigation began with the realization of a load test on a site located within an experimental section line 9 of the Barcelona Metro. The conclusions drawn about its behavior allowed the development of numerical models, both 2D and 3D, validated with the experimental results. This research also includes the study of the longitudinal behavior of the lining in order to determine the extent to which longitudinal compression initially introduced by the TBM is dissipated over time due to the influence of lining creep, which determines the longitudinal interaction between adjacent rings. Finally, the effect on the segmental lining design of taking into account its 3D response subjected to both, typical distributed design loads, or localized actions that would occur in special or accidental conditions is appraised.

  • Effect of variations in thermal-curing cycle on the cracking risk of precast segmental tunnel lining

     Crespo, Maria D.; Molins Borrell, Climent; Mari Bernat, Antonio Ricardo
    Construction & building materials
    Vol. 49, p. 201-213
    DOI: 10.1016/j.conbuildmat.2013.07.078
    Date of publication: 2013
    Journal article

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    This paper analyzes, both experimentally and numerically, the effect of thermal curing on the evolution of temperatures, rate of temperature rise and cooling, stresses and strengths in reinforced concrete elements. It also describes the experimental program carried out to characterize thermally and mechanically the high strength concrete used in the precast segments of the Pajares Tunnel lining. The thermo numerical analysis allows verifying whether a given cycle complies with rules of good practice with regard to maximum temperatures reached within the segment and maximum rates of heating and cooling. The mechanical analysis allows evaluating the cracking risk by comparing the evolution of stress and effective strength at the points of the segments that have higher risk of cracking. The developed computational tool can be used as a virtual laboratory to determine the curing cycle that is most appropriate for each type of segment

  • Characterization of the properties of steel fiber reinforced concrete by means of the generalized Barcelona test

     Carmona Malatesta, Sergio; Aguado De Cea, Antonio; Molins Borrell, Climent
    Construction & building materials
    Vol. 48, p. 592-600
    DOI: 10.1016/j.conbuildmat.2013.07.060
    Date of publication: 2013-11
    Journal article

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  • IDENTIFICACION DE PARAMETROS MECANICO-RESISTENTES EN OBRA DE FABRICA ESTRUTURAL

     Molins Borrell, Climent; Pelà, Luca; Gil Espert, Lluis; Cornado Bardon, Cossima; Serrà Martín, Isabel; Diaz Gomez, Cesar; Roca Fabregat, Pedro
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  • Study of the sensitivity of different building structures to tunneling induced settlements

     Molins Borrell, Climent; Camos Andreu, Carles
    International Conference on Structures and Architecture
    p. 704-711
    Presentation's date: 2013-07-24
    Presentation of work at congresses

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    The sensitivity of urban buildings to tunneling induced settlements can vary according to the structural types and building materials. Very few studies deal with this particular field and, for design purposes, heuristic approaches are applied based on the studies developed in UK in the 1970's. From the statistical results of a sample of buildings located over the influence zones of the L9 metro line in Barcelona, three types of structures were devised to include most of them: (1) pure masonry buildings, (2) buildings combining masonry bearing walls and RC slabs and (3) buildings with RC structural frame with masonry infill. The paper discusses the numerical simulation of such structural types in service conditions and presents the particular phenomena (cracking of masonry and concrete, gapping between masonry walls and the RC beams or columns) that should be taken into account to assess the sensitivity of these buildings to tunneling settlements.

    he sensitivity of urban buildings to tunneling induced settlements can vary according to the structural types and building materials. Very few studies deal with this particular field and, for design purposes, heuristic approaches are applied based on the studies developed in UK in the 1970's. From the statistical results of a sample of buildings located over the influ- ence zones of the L9 metro line in Barcelona, three types of structures were devised to include most of them: (1) pure masonry buildings, (2) buildings combining masonry bearing walls and RC slabs and (3) buildings with RC structural frame with masonry infill. The paper discusses the numerical simulation of such structural types in service conditions and presents the particular phenomena (cracking of masonry and concrete, gapping between masonry walls and the RC beams or columns) that should be taken into account to assess the sensitivity of these buildings to tunneling settlements.

  • A 3D temporal evolutionary numerical model of a masonry building in Barcelona subjected to tunnelling subsidence

     Camos Andreu, Carles; Molins Borrell, Climent
    International Conference Computational Methods in Tunneling and Subsurface Engineering
    p. 495-506
    Presentation's date: 2013-04-17
    Presentation of work at congresses

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    The aim of this work is to deepen the knowledge of the numerical simulation used in the prediction of building damage produced by tunnelling subsidence. This paper analyzes the structural response of a one-storey building subjected to real ground movements experienced during the construction of the L9 Metro line tunnel in Barcelona, bored by a Earth Pressure Balance Machine (EPB) Tunnel Boring Machine (TBM). A 3D temporal evolutionary numerical model is used to predict the damage in the building resulting from tunnelling subsidence. The real structural damage presented is compared with the predictions of the numerical model. This last task can be done since the measures of real ground movements given by the monitoring instruments, such as retro-reflective prisms and total stations, are available for this research. Main model parameters have been determined by means of characterization experiments developed on the site and in the laboratory, thus giving a higher significance to the analysis.

    The aim of this work is to deepen the knowledge of the numerical simulation used in the prediction of building dam age produced by tunnel ling subsidence. This paper analyzes the structural response of a one-storey building subjected to real ground movements experienced during the construction of the L9 Metro line tunnel in Barcelona, bored by a Earth Pressure Balance Machine (EPB) Tunnel Boring Machine (TBM). A 3D temporal evolutionary numerical model is used to predict the damage in the building resulting from tunnelling subsidence. The real structural damage presented is compared with the predictions of the numerical model. This last task can be done since the measures of real ground movements given by the monitoring instruments, such as retro -reflective prisms and total stations, are available for this research. Main model parameters have been determined by means of characterization experiments developed on the site and in the laboratory, thus giving a higher significance to the analysis.

  • Enginyeria de la Construcció

     Molins Borrell, Climent
    Date of publication: 2013-01
    Book chapter

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  • Development of a probabilistic model for the prediction of building damage due to tunneling induced settlements

     Camos Andreu, Carles; Molins Borrell, Climent; ¿packová, Olga; Straub, Daniel
    International Symposium on Geotechnical Safety and Risk
    p. 485-491
    Presentation's date: 2013-11
    Presentation of work at congresses

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    Tunnel construction can cause deformations of the surrounding ground, which endanger buildings and other structures located in the vicinity of the tunnel. The prediction of these deformations and the damages to the buildings is difficult due to limited knowledge of the geotechnical conditions and uncertainty in the response of the structures to the settlements. This paper presents a probabilistic model for prediction of the damage to buildings due to tunneling, which combines the volume loss method with the equivalent beam model. It furthermore proposes a probability-based method for determination of the limiting value of settlement that is used for control purposes during the tunnel construction. Updating of the limiting settlement with measurements gathered during the construction is described. The proposed methodology is applied to a masonry building affected by the construction of the L9 metro line tunnel in Barcelona.

  • Ensayo de doble punzamiento para caracterizar concreto reforzado con fibra. Nuevo método: ensayo Barcelona

     Aire, Carlos; Molins Borrell, Climent; Aguado De Cea, Antonio
    Congreso Nacional de Ingeniería Civil
    Presentation's date: 2013-11-27
    Presentation of work at congresses

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    Micro-modeling of stack bond masonry in compression using a plasticity law  Open access

     Drougkas, Anastasios; Molins Borrell, Climent; Roca Fabregat, Pedro
    International Conference on Computational Plasticity Fundamentals and Applications
    p. 919-928
    Presentation's date: 2013-09
    Presentation of work at congresses

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    A set of experimental tests to determine the compressive strength of masonry stack prisms has been numerically simulated using a combined plasticity-smeared crack constitutive law employed in three-dimensional analysis. Supported by an experimental campaign for the mechanical characterization of lime mortar masonry, a series of finite element analyses was performed in an attempt to assess the capacity of the model to reproduce the results obtained in terms of capacity, failure mode and global stiffness. The constitutive law used for the non-linear analysis of the masonry is a combination of a smeared cracking model in tension and a pressure dependent plasticity model in compression, which is capable of accounting for all failure mechanisms that may arise in concentric compression of masonry, both in the units and in the mortar. The purpose of this investigation is to establish whether a numerical approach based on the micro-modeling method is suitable for the simulation of the salient features encountered in masonry under compression as well as highlighting the main material properties necessary to be determined in order to properly model such experiments. The results are expanded upon through a parametric investigation.

  • Studies and repair of the railway bridge of Soller in Mallorca

     Molins Borrell, Climent
    International Conference on Arch Bridges
    p. 581-588
    Presentation's date: 2013-10-03
    Presentation of work at congresses

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    The studies and the repair works that were carried out on the railway bridge of Monts Reials in Sòller, which is the main city in the north-west coast of Mallorca , are described. The bridge presents five barrel vaults spanning eight meters with a width of 3.6 m and a depth of 0.60 m. The bridge was in a general good condition except for the first arch which presented some significant cracks, including very wide transversal cracks close to the abutments and spalling of the brick fabric just under the key of the arch. The assessment of the arch included the review of design documentation, full geometrical characterization of the arch, dynamic load tests and finite element analysis to check the capacity of the arch and interpret the causes of the damage. Repair works consisted of grouting of the arch ring, particularly in the cracks, repointing of the intrados of the barrel vault and the voussoirs and a watertight layer on the extrados.

    The studies and the repair works that were carried out on the railway bridge of Monts Reials in Sòller, which is the main city in the north-west coast of Mallorca , are described. The bridge presents five barrel vaults spanning eight meters with a width of 3.6 m and a depth of 0.60 m. The bridge was in a general good condition except for the first arch which presented some significant cracks, including very wide transversal cracks close to the abutments and spalling of the brick fabric just under the key of the arch. The assessment of the arch included the review of design documentation, full geometrical characterization of the arch, dynamic load tests and finite element analysis to check the capacity of the arch and interpret the causes of the damage. Repair works consisted of grouting of the arch ring, particularly in the cracks, repointing of the intrados of the barrel vault and the voussoirs and a watertight layer on the extrados.

  • AFOSP ¿ WP1: analysis of the state of the art

     Molins Borrell, Climent
    Date: 2012-12-17
    Report

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    Steel fiber reinforced concrete pipes. Part 1: technological analysis of the mechanical behavior  Open access

     Domingues de Figueiredo, Antonio; de la Fuente Antequera, Alberto; Aguado De Cea, Antonio; Molins Borrell, Climent; Chama Neto, Pedro Jorge
    IBRACON structures and materials journal
    Vol. 5, num. 1, p. 1-11
    Date of publication: 2012-01
    Journal article

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    This paper is the first part of an extensive work focusing the technological development of steel fiber reinforced concrete pipes (FRCP). Here is presented and discussed the experimental campaign focusing the test procedure and the mechanical behavior obtained for each of the dosages of fiber used. In the second part (“Steel fiber reinforced concrete pipes. Part 2: Numerical model to simulate the crushing test”), the aspects of FRCP numerical modeling are presented and analyzed using the same experimental results in order to be validated. This study was carried out trying to reduce some uncertainties related to FRCP performance and provide a better condition to the use of these components. In this respect, an experimental study was carried out using sewage concrete pipes in full scale as specimens. The diameter of the specimens was 600 mm, and they had a length of 2500 mm. The pipes were reinforced with traditional bars and different contents of steel fibers in order to compare their performance through the crushing test. Two test procedures were used in that sense. In the 1st Series, the diameter displacement was monitored by the use of two LVDTs positioned at both extremities of the pipes. In the 2nd Series, just one LVDT is positioned at the spigot. The results shown a more rigidity response of the pipe during tests when the displacements were measured at the enlarged section of the socket. The fiber reinforcement was very effective, especially when low level of displacement was imposed to the FRCP. At this condition, the steel fibers showed an equivalent performance to superior class pipes made with traditional reinforced. The fiber content of 40 kg/m3 provided a hardening behavior for the FRCP, and could be considered as equivalent to the critical volume in this condition.

  • Framework to predict the orientation of fibers in FRC: a novel philosophy

     Laranjeira de Oliveira, Filipe; Aguado De Cea, Antonio; Molins Borrell, Climent; Grünewald, Steffen; Walraven, Joost; Pialarissi Cavalaro, Sergio Henrique
    Cement and concrete research
    Vol. 42, num. 6, p. 752-768
    DOI: 10.1016/j.cemconres.2012.02.013
    Date of publication: 2012-06
    Journal article

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  • Numerical model for the analysis up to failure of precast concrete sections

     de la Fuente Antequera, Alberto; Aguado De Cea, Antonio; Molins Borrell, Climent; Armengou, Jaume
    Computers & structures
    Vol. 106-107, p. 105-114
    DOI: 10.1016/j.compstruc.2012.04.007
    Date of publication: 2012-09
    Journal article

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    Longitudinal time-dependent response of segmental tunnel linings  Open access

     Arnau Delgado, Oriol; Molins Borrell, Climent; Blom, C.B.M.; Walraven, Joost
    Tunnelling and underground space technology
    Vol. 28, num. 1, p. 98-108
    DOI: 10.1016/j.tust.2011.10.002
    Date of publication: 2012-03
    Journal article

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    The longitudinal forces introduced by tunnel boring machines (TBMs) to the segmental tunnel linings influence their structural response. The analyses of the linings construction process and the ground-structure interaction mechanisms have shown the influence of the lining creep on the progressive loss of the initial longitudinal force. An analytical formulation to predict the remaining compression of the linings as a function of time is proposed, supported by means of a complete numerical model, which considers the effect of creep during the sequential construction process. An experimental program to determine the creep of plastic packers was developed, revealing its significant influence on the global lining creep factor and the evolution of the remaining compressive stresses.

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    Three dimensional structural response of segmental tunnel linings  Open access

     Arnau Delgado, Oriol; Molins Borrell, Climent
    Engineering structures
    Vol. 44, p. 210-221
    DOI: 10.1016/j.engstruct.2012.06.001
    Date of publication: 2012-11
    Journal article

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    The particular configuration of segmental tunnel linings produces that its structural response in front of usual design loads could present a significant three dimensionality due to the structural interaction between adjacent rings (coupling effects). The present paper studies the phenomena associated to coupling effects, determines the main involved parameters and analyzes their influence on a real lining structural response by means of a 3D numerical model. The comparison with the usual plane models currently employed in linings designs provide significant conclusions about the coupling effects implications and the conditions in which become more relevant.

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    Steel fiber reinforced concrete pipes. Part 2: Numerical model to simulate the crushing test  Open access

     de la Fuente Antequera, Alberto; Domingues de Figueiredo, Antonio; Aguado De Cea, Antonio; Molins Borrell, Climent; Chama Neto, Pedro Jorge
    IBRACON structures and materials journal
    Vol. 5, num. 1, p. 12-25
    Date of publication: 2012-01
    Journal article

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    This paper is part of an extensive work about the technological development, experimental analysis and numerical modeling of steel fibre reinforced concrete pipes. The first part (“Steel fibre reinforced concrete pipes. Part 1: technological analysis of the mechanical behavior”) dealt with the technological development of the experimental campaign, the test procedure and the discussion of the structural behavior obtained for each of the dosages of fibre used. This second part deals with the aspects of numerical modeling. In this respect, a numerical model called MAP, which simulates the behavior of fibre reinforced concrete pipes with medium-low range diameters, is introduced. The bases of the numerical model are also mentioned. Subsequently, the experimental results are contrasted with those produced by the numerical model, obtaining excellent correlations. It was possible to conclude that the numerical model is a useful tool for the design of this type of pipes, which represents an important step forward to establish the structural fibres as reinforcement for concrete pipes. Finally, the design for the optimal amount of fibres for a pipe with a diameter of 400 mm is presented as an illustrating example with strategic interest.

  • Q-00029

     Gironella i Cobos, Framcesc Xavier; Campos Hortigüela, Alexis; Molins Borrell, Climent
    Competitive project

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  • Ensayo de doble punzonamiento (ensayo Barcelona) para caracterizar el comportamiento del hormigón reforzado con fibra

     Aire, Carlos; Aguado De Cea, Antonio; Molins Borrell, Climent
    Congreso Internacional y Reunión Técnica Asociación Argentina de Tecnología del Hormigón
    p. 335-342
    Presentation's date: 2012-11-07
    Presentation of work at congresses

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    Tradicionalmente, para caracterizar el comportamiento del hormigón reforzado con fibra se realizan ensayos de flexotracción en vigas. Sin embargo, existen otros procedimientos que debido a la complejidad y variabilidad de sus resultados no son considerados como procedimientos sistemáticos de control. Recientemente, se desarrolló un nuevo método llamado ensayo Barcelona, como una alternativa para determinar la resistencia a tracción indirecta del hormigón reforzado con fibra. Es un ensayo de fácil ejecución mediante el cual un cilindro de 150 mm de diámetro y 150 mm de altura, se someten a ensayo de doble punzonamiento. El método permite obtener la resistencia a tracción del hormigón confinado con fibra con coeficientes de variación menor a los obtenidos por otros métodos. Este artículo presenta un estudio comparativo entre los resultados de resistencia y tenacidad aplicando el ensayo Barcelona y el de Flexotracción.

  • An attempt to the determination of the partial safety factor for SFRC members subjected to bending forces

     Camos Andreu, Carles; Casas Rius, Joan Ramon; Molins Borrell, Climent
    RILEM International Symposium on Fibre Reinforced Concrete
    p. 1-10
    Presentation's date: 2012-09-20
    Presentation of work at congresses

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    In the last few years, research on techniques that permit the reduction or even the complete elimination of structural bar reinforcements has been intensified. The addition of steel fibres to the concrete matrix is proven to be an effective way of covering the deficiencies in this material when subjected to tensile stress. However, there still exists uncertainty surrounding some of the basis of design of structural members in ultimate condition. A clear example is the partial safety factor applied to the tensile strength. In this paper, a reliability-based analysis is carried out through the study of a particular application, such as the tunnel lining concrete segments built in an experimental section of the L9 Metro tunnel in Barcelona, solely reinforced with steel fibres. Specimens were extracted from three different segments and tested in tension by using the Barcelona test. Such a representative sample of tensile strength results made possible an assessment of the degree of the existing safety in this particular case by applying the reliability method FORM. The reliability analysis suggested a partial factor equal to 1.77. This would represent a first step to obtain the general material safety factor, which may involve a calibration in a wide range of tunnel segments and afterwards, other structural members and applications of SFRC.

  • Numerical simulation of the structural behaviour of buildings under tunnelling settlements: a case study in the L9 metro line (Barcelona)

     Camos Andreu, Carles; Molins Borrell, Climent; Arnau Delgado, Oriol; Gálvez, Javier
    International Conference on Structural Analysis of Historical Construction
    p. 432-440
    Presentation's date: 2012-10-15
    Presentation of work at congresses

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  • A new design method for steel fibre reinforced concrete pipes

     de la Fuente Antequera, Alberto; Campos Escariz, Renata; Domingues de Figueiredo, Antonio; Molins Borrell, Climent; Aguado De Cea, Antonio
    Construction & building materials
    Vol. 30, p. 547-555
    DOI: 10.1016/j.conbuildmat.2011.12.015
    Date of publication: 2012-05
    Journal article

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  • Generalization of the Barcelona test for the toughness control of FRC

     Carmona Malatesta, Sergio; Aguado De Cea, Antonio; Molins Borrell, Climent
    Materials and structures
    Vol. 45, num. 7, p. 1053-1069
    DOI: 10.1617/s11527-011-9816-8
    Date of publication: 2012-07
    Journal article

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  • Enginyeria de la construcció

     Molins Borrell, Climent
    Date of publication: 2012-01-31
    Book chapter

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    Tot i l'habitual creixement en potència i nuclis dels microprocessadors, l'any va tenir com a gran novetat l'estabilització del nou mercat dels telèfons intel·ligents (smartphones) i, sobre tot, de les "tauletes" (tablets), on diversos fabricants van començar a fer competència als iPhone i iPad d'Apple que ja van comercialitzar noves versions durant l'any 2011. També cal destacar que va crèixer de la idea de la "inf ormàtica verda" (green computing) respectuosa amb el medi ambient i, sobre tot, la força de les xarxes socials quasi ja del tot imprescindibles. Sense oblidar la desaparició, en poques setmanes, de tres personatges que han estat fonamentals en diversos aspectes de la informàtica moderna, ni els esforços d'Europa per estar al dia en el tema dels projectes de futur de les TIC. També és novetat l’arribada d’Amazon a Espanya, a partir de setembre d’enguany. Això suposa, entre d’altres coses, una empenta a la venda del seu lector de eBooks Kindle que es proposa com a regal nadalenc.

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  • Numerical Approach For Modeling Steel Fiber Reinforced Concrete  Open access

     Pros Parés, Alba
    Universitat Politècnica de Catalunya
    Theses

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    One alternative to overcome the main drawbacks of plain concrete in tension (its brittleness and weakness) is Steel Fiber Reinforced Concrete (SFRC), a technique introduced in the 70's, which consists of adding steel fibers into the concrete matrix. Due to the presence of the steel fibers into the concrete matrix, the residual strength and the energy dissipation of the material increase. Moreover, once a crack appears in the concrete, the steel fibers sew this fissure. The shape, the length and the slenderness of the fibers influence on the SFRC behavior. Moreover, the distribution and the orientation of the fibers into the concrete domain must be taken into account for characterizing the material. In order to characterize the behavior of SFRC, a numerical tool is needed. The aim is to simulate the most standard and common tests (direct and indirect tension tests, flexural test, double punch tes,¿) and more complex setups. This thesis proposes a numerical tool for modeling SFRC avoiding homogenized models (not accurate enough) and conformal meshes (too expensive). Therefore, the numerical tool accounts for the actual geometry of the fibers, discretized as 1D bars nonconformal with the concrete bulk mesh (2D or 3D domains). The two materials, corresponding to the concrete bulk and the fiber cloud, are defined independently, but coupled by imposing displacement compatibility. This compatibility is enforced following the ideas of the Immersed Boundary methods. Two different models are considered for modeling the concrete bulk (a continuous one and a discontinuous one). The parametric study of each model is done for only plain concrete, before the addition of the steel fibers. A phenomenological mesomodel is defined for modeling steel fibers, on the basis of the analytical expressions describing the pullout tests. This phenomenological mesomodel not only describes the behavior of the steel fibers, but also accounts for the concrete-fiber interaction behavior. For each fiber, its constitutive equation is defined depending on its shape (straight or hooked) and the angle between the fiber and the normal direction of the failure pattern. Both 2D and 3D examples are reproduced with the proposed numerical tool. The obtained results illustrate the presence of the steel fibers into the concrete matrix. The shape of the fiber influences of the SFRC behavior: the residual strength is higher for hooked fibers than for straight ones. Moreover, increasing the quantity of fibers means increasing the residual strength of the material. The obtained numerical results are compared to the experimental ones (under the same hypothesis). Therefore, the proposed numerical approach of SFRC is validated experimentally.

  • Structural Response of Precast Concrete Segmental Tunnel Linings  Open access

     Arnau Delgado, Oriol
    Department of Construction Engineering, Universitat Politècnica de Catalunya
    Theses

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    The increasing use of the tunnel boring machines (TBMs) has entailed their own evolution and the improvement of the construction processes applied, allowing the construction of tunnels on more complex hydro-geological conditions. These new drilling facilities imply that higher ground and water pressures have to be resisted by the structural lining, turning its design into a key item in all current tunnel projects. TBMs construction process is mainly associated to precast concrete segmental tunnel linings, which are consisted of concrete rings sequentially placed as the tunnel drilling advances. Despite segmental tunnel linings are widely used, their structural response presents significant uncertainties due to the particular configuration on multiple precast pieces and the evolutionary construction process applied. The improvement and optimization of segmental tunnel linings, necessary to obtain safer structures at a lower cost, requires a significant advance in the knowledge of their structural response and about the appropriate techniques to properly reproduce it. This PhD thesis present the mechanisms and phenomena involved in the structural response of precast concrete segmental tunnel linings, detailing numerical modeling strategies to properly simulate them. The integration of all these techniques in a unique model allows the analysis of a real tunnel lining subjected to different scenarios, determining the influence and relevance of the main parameters defining a tunnel and its structural lining. Present research departs from an innovative in situ test carried out at Line 9 subway tunnel in Barcelona. The treatment and analysis of the obtained data provides experimental evidences about the structural response of segmental tunnel linings and the main involved mechanisms and phenomena. Different numerical simulation strategies are developed in order to properly reproduce such mechanism and phenomena, achieving a reliable simulation of an isolated ring response. The longitudinal response of the segmental concrete linings is obtained through the detailed study of the construction process applied and the ground-structure interaction mechanisms. The knowledge of the longitudinal force present at a segmental tunnel lining is of paramount importance in order to determine the interaction degree between adjacent rings and the consequent three-dimensionality of the lining response. Finally, the numerical simulation of a real tunnel section subjected to different scenarios of load and boundary conditions determines the influence of the three-dimensional effects on segmental concrete linings response, concluding about its structural implications in respect to the isolated ring approach usually employed in design processes.

  • Numerical tool for modeling steel fiber reinforced concrete

     Molins Borrell, Climent; Pros Parés, Alba; Diez Mejia, Pedro
    RILEM International Symposium on Fibre Reinforced Concrete
    p. 1-9
    Presentation's date: 2012-09-20
    Presentation of work at congresses

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    Steel Fiber Reinforced Concrete (SFRC) allows overcoming brittleness and weakness in tension, the main drawbacks of plain concrete. The goal of the present presentation is to present an ad-hoc numerical strategy to account for the contribution of the fibers in the simulation of the mechanical response of SFRC. In the model presented, the individual fibers immersed in the concrete bulk are accounted for in their actual location and orientation. The selected approach is based on the ideas introduced in the Immersed Boundary (IB) methods. These methods were developed to account for 1D (or 2D) solids immersed in 2D (or 3D) fluids. Here, the concrete bulk is playing the role of the fluid and the cloud of steel fibers is acting as the immerse boundary (that is a 1D structure in a 2D or 3D continuous). Thus, the philosophy of the IB methodology is used to couple the behavior of the two systems, the concrete bulk and the fiber cloud, precluding the need of matching finite element meshes. In the proposed approach, the meshes of the concrete bulk and fiber cloud are independent and the models are coupled imposing displacement compatibility and equilibrium of the two systems. The concrete bulk is modeled using any nonlinear model. The constitutive model for the fibers is designed to account for the complex interaction between fibers and concrete. The fiber models are based on previous investigations describing the concrete-fiber interaction and its dependence on the factors identified to be relevant: shape of the fiber (straight or hooked) and angle between the fiber and the crack plane. 3D examples with fibers distributed and oriented randomly are reproduced using the proposed approach.

  • Influence of fibre orientation on the performance of steel fibre-reinforced concrete

     Grünewald, Steffen; Laranjeira de Oliveira, Filipe; Walraven, Joost; Aguado De Cea, Antonio; Molins Borrell, Climent
    RILEM International Symposium on Fibre Reinforced Concrete
    p. 1-12
    Presentation's date: 2012-09-19
    Presentation of work at congresses

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    The performance of fibre-reinforced materials in the hardened state depends on the material behaviour, the production method and influences related to the structure. The position and the orientation of fibres in a structure can differ from the homogenous distribution and the random orientation in a mixer. Due to the flow of the concrete, fibres are able to orient which makes the prediction of the structural behaviour of fibre-reinforced concrete more complex, but it also offers the potential for an improved structural performance. Synergetic effects were observed with regard to flowable concrete related to the fibre efficiency. This paper discusses two studies on the effect of fibre orientation on the performance of steel fibre- reinforced concrete. The first study discusses the relation between fibre orientation and the distribution of fibre orientation. The analysis indicates that the variation of fibre orientation follows a Gaussian law and the distribution of fibre orientation can be predicted from the average fibre orientation. The second study on tunnel segments discusses the influence of production on the fibre orientation and how this affects the splitting tensile strength. The fibre orientation affects the fibre efficiency and the structural performance of steel fibre-reinforced concrete.

  • Use of double punching test (Barcelona test) for quality control of fiber reinforced concretes

     Carmona Malatesta, Sergio Alejandro; Aguado De Cea, Antonio; Molins Borrell, Climent
    International Conference: Concrete in the Low Carbon Era
    p. 1-10
    Presentation's date: 2012-07
    Presentation of work at congresses

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    Traditionally, flexural testing is used to characterize the strength and post–peak behavior of fiber–reinforced concretes (FRC). Nevertheless, these tests results exhibit a high dispersion, and therefore invalidate their use as tests for the systematic control of FRCs in works. Also, they have the disadvantage of being complex tests, which require heavy specimens and highly qualified staff. With the aim to solve these problems, an indirect tensile test based on double punching test set up, called the Barcelona test, has been proposed to control tensile behavior of FRC. This test requires smaller specimens, with a high specific surface of fracture, allowing obtain values representative of strength and toughness of materials, with considerably less dispersion than other experimental methodologies, and was recently standardized in Spain. This paper presents the results of an experimental program, which validate the use of Barcelona test as a suitable methodology to systematic characterization FRC in works.

  • Fibre reinforced concrete pipes: new designing trends

     de la Fuente Antequera, Alberto; Domingues de Figueiredo, Antonio; Aguado De Cea, Antonio; Molins Borrell, Climent; Campos Escariz, Renata
    RILEM International Symposium on Fibre Reinforced Concrete
    p. 1-12
    Presentation's date: 2012-09-21
    Presentation of work at congresses

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  • A new approach on crushing strength test for fibre reinforced concrete pipes

     Domingues de Figueiredo, Antonio; de la Fuente Antequera, Alberto; Molins Borrell, Climent; Aguado De Cea, Antonio
    RILEM International Symposium on Fibre Reinforced Concrete
    p. 1-13
    Presentation's date: 2012-09-21
    Presentation of work at congresses

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  • Procedimiento de instalación y mantenimiento de estructura flotante monolítica para soporte de aerogenerador

     Molins Borrell, Climent; Rebollo Pericot, Josep; Campos Hortigüela, Alexis
    Date of request: 2012-02-10
    Invention patent

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    Proceso de instalación de estructura flotante monolítica para soporte de aerogenerador en zonas marítimas de gran profundidad y alejadas de la costa que consiste en el fondeo de la estructura desde una posición horizontal de transporte hasta la vertical mediante la inundación controlada de su interior, de forma que el tramo emergente sobre la superficie marina sea mínimo, para que el montaje del aerogenerador a instalar en la coronación se realice a través de una embarcación tipo catamarán o similar y sin necesidad de medios complementarios de elevación. El emergido de la estructura se realiza mediante extracción del agua interior a través de diversas válvulas a lo largo de la altura que se equilibra parcialmente con el lastre tipo granular introducido a través de una apertura lateral. La fuerza en los amarres de sujeción se aplica mediante el ajuste de la línea de flotación de la estructura.

  • Proceso de sustitución o remoción de aerogenerador en estructuras flotantes monolíticas tipo SPAR

     Molins Borrell, Climent; Rebollo Pericot, Josep; Campos Hortigüela, Alexis
    Date of request: 2012-03-14
    Invention patent

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    Proceso de sustitución o remoción de aerogenerador en estructuras flotantes monolíticas tipo SPAR.

    La presente invención hace referencia al proceso de sustitución de un aerogenerador en una estructura flotante monolítica tipo SPAR fondeada.

    La invención se basa en la inundación controlada de la estructura flotante tal que la coronación de la estructura quede situada a una altura sobre el nivel medio del mar (NMM), entre 5 y 20 m, para que la coronación de la estructura y el aerogenerador sean fácilmente accesibles desde la cubierta de una embarcación tipo catamarán que se acople a la estructura y, mediante un sistema de puente grúa o similar, efectuar tareas de mantenimiento y/o sustitución sin necesidad de grúas flotantes. Finalizadas dichas tareas, la estructura se emerge mediante evacuación por bombeo del agua interior, permitiendo también reajustar la línea de flotación y la tensión en los amarres si las nuevas condiciones de masa lo requieren.

  • Memoria técnica módulo de 6,0 m de altura

     Molins Borrell, Climent; Mirambell Arrizabalaga, Enrique
    Date: 2011-06-28
    Report

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  • Modeling steel fiber reinforced concrete: numerical immersed boundary approach and a phenomenological mesomodel for concrete-fiber interaction

     Pros Parés, Alba; Diez Mejia, Pedro; Molins Borrell, Climent
    International journal for numerical methods in engineering
    Vol. 90, num. 1, p. 65-86
    DOI: 10.1002/nme.3312
    Date of publication: 2011-11-30
    Journal article

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  • Access to the full text
    Experimental and analytical study of the structural response of segmental tunnel linings based on an in situ loading test. Part 2: Numerical simulation  Open access

     Arnau Delgado, Oriol; Molins Borrell, Climent
    Tunnelling and underground space technology
    Vol. 26, num. 6, p. 778-788
    DOI: 10.1016/j.tust.2011.04.005
    Date of publication: 2011-11
    Journal article

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    The numerical simulation of the in situ test described in the part 1 of the paper is performed by means of two different approaches: a 2D plane stress model and a 3D shell elements model. A consistent modeling of the tunnel behavior is achieved through the proper simulation of the main phenomena involved on the structural response of the lining: (1) the steel fiber reinforced concrete (SFRC) post-cracking behavior, (2) the detailed behavior of the joints between segments and (3) the ground–structure interaction. The origin and the effects of all these phenomena and the modeling techniques employed to simulate them are carefully described and discussed. Finally, the results obtained are compared with the experimental evidences, showing the excellent accuracy achieved in terms of displacements, joints closures and crack patterns.

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  • Diseño óptimo integral de tubos de hormigón

     de la Fuente Antequera, Alberto; Aguado De Cea, Antonio; Molins Borrell, Climent
    Hormigon y acero
    num. 260, p. 77-91
    Date of publication: 2011-04-01
    Journal article

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  • Nonlinear response of masonry wall structures subjected to cyclic and dynamic loading

     Sima Brum, Jose Fernando; Roca Fabregat, Pedro; Molins Borrell, Climent
    Engineering structures
    Vol. 33, num. 6, p. 1955-1965
    DOI: 10.1016/j.engstruct.2011.02.033
    Date of publication: 2011-06
    Journal article

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    The assessment of the dynamic or seismic performance of complex structures often requires the integration in the time domain of the structural equation of motion in the frame of a nonlinear analysis. Although sophisticated methods have been developed for the nonlinear analysis of masonry wall structures, including the macro- and micro-modeling approaches, these require large computational effort still limiting the extent and complexity of the structures analyzed. This paper presents an alternative method based on the Generalized Matrix Formulation for masonry skeletal structures and load bearing wall systems, which has been proved as an efficient formulation for the analysis of the strength capacity of these kinds of structures (Roca et al. (2005) [17]). The basic formulation has been complemented with a uniaxial cyclic constitutive model for masonry and a time integration scheme. The ability of the resulting approach to predict the nonlinear dynamic response of masonry structures is shown through its application to the time domain analysis of an experimental scale masonry building with available experimental results on its dynamic response.

  • Innovations on components and testing for precast panels to be used in reinforced earth retaining walls

     de la Fuente Antequera, Alberto; Aguado De Cea, Antonio; Molins Borrell, Climent; Armengou, Jaume
    Construction & building materials
    Vol. 25, num. 5, p. 2198-2205
    DOI: 10.1016/j.conbuildmat.2010.11.003
    Date of publication: 2011-05
    Journal article

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