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  • Diagnostic load testing and assessment of existing bridges: examples of application

     Olaszek, Piotr; Lagoda, Marek; Casas Rius, Joan Ramon
    Structure and infrastructure engineering
    Vol. 10, num. 6, p. 834-842
    DOI: 10.1080/15732479.2013.772212
    Date of publication: 2014
    Journal article

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    Load testing method is a significant tool in the assessment of bridge safety. One type of load tests is diagnostic load testing, the aim of which is to establish a comparison between real bridge behaviour and analytical calculation. It can be used either as acceptance test of the structures or as an estimation tool for the load carrying capacity of the already existing structures that have been in service for some time. This article presents diagnostic load tests and three examples of their application to various bridge structures and emphasises their diagnostic potential for assessment. In the majority of cases of diagnostic load tests presented in the literature, the experimental results (deflections, strains, etc) are very close or lower than the predicted ones and for this reason, such tests are expected to validate the existing structure. However, in the cases presented here, it is shown how the experimental results differ considerably from the expected ones. Since the theoretical and the experimental results of all three examples did not match, it was highly recommended to keep the matter under close investigation. A deep insight into the bridges showed serviceability and safety concerns and in some cases a repair/strengthening was necessary.

  • Novel isolation device for protection of cable-stayed bridges against near-fault earthquakes

     Ismail Abdelkareem Moustafa, Mohammed; Casas Rius, Joan Ramon
    ASCE. Journal of bridge engineering
    Vol. 19, num. 8, p. A4013002-1-A4013002-12
    DOI: 10.1061/(ASCE)BE.1943-5592.0000509
    Date of publication: 2014-08
    Journal article

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    This paper investigates the near-fault (NF) seismic performance of a novel isolation system, referred to as the roll-n-cage (RNC) isolator, considering the cable-stayed Bill Emerson Memorial Bridge in Missouri. The RNC isolator is designed to achieve a balance in controlling bridge displacement demands, structural accelerations, and internal forces in the tower attributable to horizontal seismic forces. It provides in a single unit all the necessary functions of rigid support, horizontal flexibility with enhanced stability, and energy-dissipation characteristics. Moreover, it has two unique features that are built-in: energy-absorbing buffer and linear recentering mechanisms. Through a nonlinear time history analysis under three recorded NF earthquakes and three synthetic ground accelerations, the results show that the RNC isolator is a convenient isolation system in protecting cable-stayed bridges against NF earthquakes.

  • Partial safety factors for CFRP-wrapped bridge piers: model assessment and calibration

     Casas Rius, Joan Ramon; Chambi Chuquichambi, José Luis
    Composite structures
    Vol. 118, p. 267-283
    DOI: 10.1016/j.compstruct.2014.07.032
    Date of publication: 2014-12
    Journal article

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    Concerning the strengthening or seismic retrofitting of bridge piers, the use of fiber reinforced polymers (FRP) has increased as an element of confinement of concrete due to its easy application and excellent mechanical and chemical properties. However, due to the lack of codes and standards and the lack of experience in the long term behavior, uncertainties exist in the calculation bases along the dimensioning of this reinforcement and more precisely in the partial coefficients of safety to be adopted for the material properties. As a consequence, bridge engineers are reluctant to use composite materials in the strengthening of damaged bridge piers. To try to overcome this problem, this paper describes the methodology for a reliability-based calibration of the partial safety factors to be used for the confined concrete in the design of strengthening to axial-bending forces using CFRP. The method requires the definition of a response model jointly with the statistical definition of the model error. This is discussed in the first part of the paper. The reliability-based procedure is developed based on the design equation and the corresponding model. A simple set of partial safety factors is finally proposed and compared with those proposed in existing guidelines.

  • Sistema de apoyo a la toma de decisiones durante el ciclo de vida de las infraestructuras: smart-infrastructures

     Aparicio Bengoechea, Angel Carlos; Casas Rius, Joan Ramon; Ramos Schneider, Gonzalo; García-fontanet Molina, Angel Juan; Gentile, Carmelo; Lozano Galant, Jose Antono; Ghosn, Michel; Turmo Coderque, Jose
    Competitive project

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  • Condition rating of concrete bridges based on structural robustness

     Anitori, Giorgio; Casas Rius, Joan Ramon; Ghosn, Michel
    International Conference on Bridge Maintenance, Safety and Management
    p. 1667-1674
    Presentation's date: 2014-07-10
    Presentation of work at congresses

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  • Coeficientes parciales de seguridad en el refuerzo de pilas de puentes con materiales compuestos CFRP

     Chambi Chuquichambi, José Luis; Casas Rius, Joan Ramon
    Congreso Latinoamericano sobre Patología de la Construcción, Tecnología de la Rehabilitación y Gestión del Patrimonio
    p. 1733-1741
    Presentation's date: 2014-04-04
    Presentation of work at congresses

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    El continuo deterioro y/o daños causados en las estructuras de hormigón durante su vida útil, han conducido al desarrollo de nuevos materiales compuestos para el refuerzo estructural. En puentes con problemas de durabilidad, daños por causas externas o con un cambio probable en su utilización o con un incremento en la carga de diseño, los métodos de refuerzo tradicional frecuentemente tienen desventajas inherentes como el incremento del peso de la estructura, la corrosión del acero y su elevado costo de manipulación y colocación. Más concretamente refiriéndonos al refuerzo de pilas de puentes, en años recientes se ha incrementado el uso de polímeros reforzados con fibra (FRP) como elemento de confinamiento de elementos de hormigón sometidos a compresión, debido a sus excelentes propiedades mecánicas y químicas, incrementando principalmente la resistencia y ductilidad de las pilas de hormigón. Sin embargo, debido a la falta de códigos y normas y la falta de experiencia en el comportamiento a largo plazo, existen incertidumbres en las bases de cálculo durante el dimensionamiento de este refuerzo. Una de ellas está precisamente en los coeficientes parciales de seguridad para el hormigón confinado que se deben adoptar en el diseño. Este artículo describe la calibración basada en la teoría de la fiabilidad estructural de coeficientes parciales de seguridad a ser utilizados para el hormigón confinado en el diseño del refuerzo de elementos sometidos a flexocompresión usando (CFRP). El procedimiento se desarrolla a partir de un modelo teórico para el hormigón confinado, cuyos parámetros estadísticos fueron obtenidos a partir de una base de datos de 126 resultados experimentales.

    El continuo deterioro y/o daños causados en las estructuras de hormigón durante su vida útil, han conducido al desarrollo de nuevos materiales compuestos para el refuerzo estructural. En puentes con problemas de durabilidad, daños por causas externas o con un cambio probable en su utilización o con un incremento en la carga de diseño, los métodos de refuerzo tradicional frecuentemente tienen desventajas inherentes como el incremento del peso de la estructura, la corrosión del acero y su elevado costo de manipulación y colocación. Más concretamente refiriéndonos al refuerzo de pilas de puentes, en años recientes se ha incrementado el uso de polímeros reforzados con fibra (FRP) como elemento de confinamiento de elementos de hormigón sometidos a compresión, debido a sus excelentes propiedades mecánicas y químicas, incrementando principalmente la resistencia y ductilidad de las pilas de hormigón. Sin embargo, debido a la falta de códigos y normas y la falta de experiencia en el comportamiento a largo plazo, existen incertidumbres en las bases de cálculo durante el dimensionamiento de este refuerzo. Una de ellas está precisamente en los coeficientes parciales de seguridad para el hormigón confinado que se deben adoptar en el diseño. Este artículo describe la calibración basada en la teoría de la fiabilidad estructural de coeficientes parciales de seguridad a ser utilizados para el hormigón confinado en el diseño del refuerzo de elementos sometidos a flexocompresión usando (CFRP). El procedimiento se desarrolla a partir de un modelo teórico para el hormigón confinado, cuyos parámetros estadísticos fueron obtenidos a partir de una base de datos de 126 resultados experimentales.

  • Influence of advanced assessment methods on the LCA of elderly bridges

     Soriano Chacon, Miriam; Casas Rius, Joan Ramon
    International Conference on Bridge Maintenance, Safety and Management
    Presentation's date: 2014-07-08
    Presentation of work at congresses

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    The present paper aims to synthesize the state-of-the-art of advanced assessment methods used in bridges and also highlights the involvement, influence and direct relationship of these methods with the different aspects currently considered in the Life-Cycle Assessment (LCA) of existing bridges. It has been shown that advanced methods like reliability-based assessment and updating data from results obtained through both Weight-in-Motion (WIM) and Structural Health Monitoring (SHM) systems led to better results than conventional methods in terms of having a more realistic understanding of the actual condition of the structure by decreasing some existing uncertainties and, therefore, resulting on a more accurate LCA, sometimes concluding that the bridge has not to be posted/strengthened/replaced. Advanced evaluation methods have a great impact on the LCA of bridges because besides reducing the maintenance and repair costs, they allow a more accurate assessment and to extend the life-span of the structure while maintaining adequate levels of performance and safety.

    The present paper aims to synthesize the state-of-the-art of advanced assessment methods used in bridges and also highlights the involvement, influence and direct relationship of these methods with the different aspects currently considered in the Life-Cycle Assessment (LCA) of existing bridges. It has been shown that advanced methods like reliability-based assessment and updating data from results obtained through both Weight-in-Motion (WIM) and Structural Health Monitoring (SHM) systems led to better results than conventional methods in terms of having a more realistic understanding of the actual condition of the structure by decreasing some existing uncertainties and, therefore, resulting on a more accurate LCA, sometimes concluding that the bridge has not to be posted/strengthened/replaced. Advanced evaluation methods have a great impact on the LCA of bridges because besides reducing the maintenance and repair costs, they allow a more accurate assessment and to extend the life-span of the structure while maintaining adequate levels of performance and safety.

  • Assessing cracking characteristics of concrete structures by distributed optical fiber and non-linear finite element modelling

     Rodríguez, Gerardo; Casas Rius, Joan Ramon; Villalba Herrero, Sergio
    European Workshop on Structural Health Monitoring
    p. 1131-1138
    Presentation's date: 2014-07-08
    Presentation of work at congresses

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    This work shows how the experimental strain data obtained with an OBR (Optical Backscattered Reflectometer) measuring system can be used to locate cracking before being visually observable and also to estimate the crack width for different levels of load. The method is checked in a test up to failure carried out on a reinforced concrete slab, where the deployement of other standard sensors allowed to validate the results from the OBR system. The results are also compared with those coming from a 2D non-linear finite element model, showing also a good agreement.

    This work shows how the experimental strain data obtained with an OBR (Optical Backscattered Reflectometer) measuring system can be used to locate cracking before being visually observable and also to estimate the crack width for different levels of load. The method is checked in a test up to failure carried out on a reinforced concrete slab, where the deployement of other standard sensors allowed to validate the results from the OBR system. The results are also compared with those coming from a 2D non-linear finite element model, showing also a good agreement.

  • Partial safety factors in strengthening of bridge piers with CFRP

     Chambi Chuquichambi, José Luis; Soriano Chacon, Miriam; Casas Rius, Joan Ramon
    International Conference on Bridge Maintenance, Safety and Management
    p. 2313-2321
    Presentation's date: 2014-07-10
    Presentation of work at congresses

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    The continuous deterioration and/or damages caused in concrete structures during their lifetime have led to the development of new composite materials used for the structural reinforcement. In bridges with durability problems, damaged by external causes or with a likely change in its use or with an increase of the design load, the traditional strengthening methods frequently have disadvantages like the increase of the weight of the structure, the corrosion of the steel and its high cost of manipulation and positioning. More specifically referring to the reinforcement of bridge piers, in recent years the use of fibre reinforced polymers (FRP) has increased as an element of confinement of concrete elements subject to compression due to its excellent mechanical and chemical properties, increasing the resistance and ductility of the piers. However, due to the lack of codes and standards and the lack of experience in the long term behaviour, uncertainties exist in the calculation bases along the dimensioning of this reinforcement and more precisely in the partial coefficients of safety to be adopted. The paper describes the reliability-based calibration of partial safety factors to be used for the confined concrete in the design of strengthening to axial-bending forces using CFRP. The reliability-based procedure is developed based on a theoretical model whose statistical parameters were obtained from a data base of 126 laboratory tests.

  • Simplified probabilistic model for maximum traffic load from weigh-in-motion data

     Soriano Chacon, Miriam; Casas Rius, Joan Ramon; Ghosn, Michel
    International Conference on Bridge Maintenance, Safety and Management
    p. 304-311
    Presentation's date: 2014-07-10
    Presentation of work at congresses

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  • Safety requirements and probabilistic models of resistance in the assessment of existing railway bridges

     Casas Rius, Joan Ramon; Wisniewski, Dawid
    Structure and infrastructure engineering
    Vol. 9, num. 6, p. 529-545
    DOI: 10.1080/15732479.2011.58167
    Date of publication: 2013-06
    Journal article

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  • Robustness of corroded reinforced concrete structures: a structural performance approach

     Cavaco, E. S.; Casas Rius, Joan Ramon; Neves, L. A. C.; Huespe, Alfredo Edmundo
    Structure and infrastructure engineering
    Vol. 9, num. 1, p. 42-58
    DOI: 10.1080/15732479.2010.515597
    Date of publication: 2013
    Journal article

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  • Application of optical fiber distributed sensing to health monitoring of concrete structures

     Villalba Herrero, Sergio; Casas Rius, Joan Ramon
    Mechanical systems and signal processing
    Vol. 39, num. 1-2, p. 441-451
    DOI: 10.1016/j.ymssp.2012.01.027
    Date of publication: 2013-08
    Journal article

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    The use of Optical Backscatter Reflectometer (OBR) sensors is a promising measurement technology for Structural Health Monitoring (SHM) as it offers the possibility of continuous monitoring of strain and temperature along the fiber. Several applications to materials used in the aeronautical construction have demonstrated the feasibility of such technique. These materials (composites, steel, aluminum) apart from having a smooth surface where the bonding of the sensor is easily carried out, they also have a continuous strain field when subject to external loading and therefore the bonding of the OBR on the material surface is not in danger for high levels of loading as the OBR can easily follow the strain in the material. The application of such type of sensor to concrete structures may present some difficulties due to (1) the roughness of the concrete surface and the heterogeneity due to the presence of aggregates of several sizes, (2) the fact that reinforced concrete cracks at very low level of load, appearance of a discontinuity in the surface and the strain field that may provoke a break or debonding of the optical fiber. However the feasibility of using OBR in the SHM of civil engineering constructions made of concrete is also of great interest, mainly because in this type of structures it is impossible to know where the crack may appear and therefore severe cracking (dangerous for the structure operation) can appear without warning of the monitoring if sensors are not placed in the particular location where the crack appears. In order to explore the potentiality of detecting cracks as they appear without failure or debonding, as well as the compatibility of the OBR bonding to the concrete surfaces, this paper shows the test carried out in the loading up to failure of a concrete slab.

  • Fatigue-safety assessment of reinforced concrete (RC) bridges: application to the Brazilian highway network

     Rodrigues, J. Fernando; Casas Rius, Joan Ramon; ALFONSO DE OLIVEIRA ALMEIDA, PEDRO
    Structure and infrastructure engineering
    Vol. 9, num. 6, p. 601-616
    DOI: 10.1080/15732479.2011.598939
    Date of publication: 2013-03
    Journal article

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  • New structural joint by rebar looping applied to segmental bridge construction: fatigue strength tests

     Villalba Herrero, Sergio; Casas Rius, Joan Ramon; Aparicio Bengoechea, Angel Carlos; Villalba Herrero, Vicente
    ASCE. Journal of bridge engineering
    Vol. 18, num. 11, p. 1174-1188
    DOI: 10.1061/(ASCE)BE.1943-5592.0000450
    Date of publication: 2013-11
    Journal article

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    The objective of this research has been to design, develop, and evaluate experimentally a modified type of construction joint of limited length between concrete slab segments. The design concept is based on an anchorage hook of reduced development length stiffened by transverse reinforcement bars. The purpose of this paper is to investigate the mechanical behavior of the joint in terms of stiffness and strength for an application that requires high durability, which often leads to serviceability problems such as cracking and water leakage at transverse joints. This can regularly appear in bridges. Additionally, bridge decks are structures that are subjected to repeated loading such as traffic loads, making it necessary to evaluate the behavior of joints under fatigue load. Therefore, studies focusing on the strength, stiffness, and serviceability of the joints must be carried out. This paper investigates experimentally the fatigue behavior and strength of loop joints with regard to the loop bar diameter, loop joint width, and applied load ranges. These results were compared with the behavior of RC slabs without joints. A total of eight slabs were fabricated for fatigue loading tests, and the failures of the different specimens (with loop joints and without) were obtained. From the test results, the mechanical behavior of the slabs with loop joints was confirmed to be similar to that of the slabs without joints. The experimental loop joint design was found to perform correctly under fatigue loads.

  • Near-fault isolation of cable-stayed bridges using RNC isolator

     Ismail Abdelkareem Moustafa, Mohammed; Casas Rius, Joan Ramon; Rodellar Benede, Jose Julian
    Engineering structures
    Vol. 56, p. 327-342
    DOI: 10.1016/j.engstruct.2013.04.007
    Date of publication: 2013-11
    Journal article

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    This paper investigates the near-fault (NF) seismic performance of a recent isolation system, referred to as Roll-N-Cage (RNC) isolator, considering the cable-stayed Bill Emerson Memorial Bridge in Missouri, USA. Under NF ground motion, the seismic isolation devices might perform poorly because of large isolator displacements caused by long-period large velocity and displacement pulses associated with such strong motion. The RNC isolator is designed to achieve a balance in controlling isolator displacement demands and structural accelerations. It provides in a single unit all the necessary functions of rigid support, horizontal flexibility with enhanced stability and energy dissipation characteristics. Moreover, it is distinguished from other isolation devices by two unique features: (1) it has a built-in energy absorbing buffer to limit the isolated deck displacement under severe seismic excitations to a preset value and (2) it has a built-in linear recentering mechanism that prevents residual displacement after earthquakes. The seismic response of the RNC-isolated cable-stayed bridge is investigated using nonlinear time history analysis under three recorded NF earthquakes and three synthetic ground accelerations that capture many of the kinematic characteristics of recorded NF ground motions. The results show that the RNC isolator is a convenient isolation system in protecting cable-stayed bridges against NF earthquakes.

    This paper investigates the near-fault (NF) seismic performance of a recent isolation system, referred to as Roll-N-Cage (RNC) isolator, considering the cable-stayed Bill Emerson Memorial Bridge in Missouri, USA. Under NF ground motion, the seismic isolation devices might perform poorly because of large isolator displacements caused by long-period large velocity and displacement pulses associated with such strong motion. The RNC isolator is designed to achieve a balance in controlling isolator displacement demands and structural accelerations. It provides in a single unit all the necessary functions of rigid support, horizontal flexibility with enhanced stability and energy dissipation characteristics. Moreover, it is distinguished from other isolation devices by two unique features: (1) it has a built-in energy absorbing buffer to limit the isolated deck displacement under severe seismic excitations to a preset value and (2) it has a built-in linear recentering mechanism that prevents residual displacement after earthquakes. The seismic response of the RNC-isolated cable-stayed bridge is investigated using nonlinear time history analysis under three recorded NF earthquakes and three synthetic ground accelerations that capture many of the kinematic characteristics of recorded NF ground motions. The results show that the RNC isolator is a convenient isolation system in protecting cable-stayed bridges against NF earthquakes.

  • Redundancy and robustness in the design and evaluation of bridges: European and North American perspectives

     Anitori, Giorgio; Casas Rius, Joan Ramon; Ghosn, Michel
    ASCE. Journal of bridge engineering
    Vol. 18, num. 12, p. 1241-1251
    DOI: 10.1061/(ASCE)BE.1943-5592.0000545
    Date of publication: 2013-12
    Journal article

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    In this paper, current and proposed methodologies for assessing the robustness and redundancy of bridge structures are discussed and an overview of the latest advances in research is presented along with proposals for implementation in bridge design and evaluation codes. In particular, European and North American standard codes and guidelines, including the Eurocode, AASHTO, and the Canadian Standards Association (CSA), as well as some national European codes and related guidelines, are compared. Research projects, including those of the European Cooperation of Science and Technology (COST) and the U.S. National Cooperative Highway Research Program (NCHRP), represent key links between research activities and the need for implementing concepts of structural redundancy and robustness into the codes. The activities undertaken by COST and NCHRP constitute attempts to synthetize, simplify, and implement theoretical concepts that have been discussed over many years. This review shows that the U.S. approach concentrates on developing tools and criteria for the numerical evaluation of the capability of a bridge structure to continue to carry load after the failure of a member, whereas the European approach, still in a more theoretical phase, lacks specific guidelines for bridges and uses available building recommendations. This paper also presents a critical assessment of the state of the art and argues that criteria implementable in future generations of bridge codes should be based on quantifiable measures of risk, which is a subject still in its very early stages of development.

  • Load rating of highway bridges by proof-loading

     Casas Rius, Joan Ramon; Gómez, Juan D.
    KSCE journal of civil engineering
    Vol. 17, num. 3, p. 556-567
    DOI: 10.1007/s12205-013-0007-8
    Date of publication: 2013-04
    Journal article

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  • 2012 Outstanding Paper Award, Scientific Paper category

     Wisniewski, Dawid; Casas Rius, Joan Ramon; Ghosn, Michel
    Award or recognition

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  • Robustness of corroded reinforced concrete structures

     Soares Riberio Gomes Cabaco, Eduardo
    Universidade Nova de Lisboa
    Theses

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    Es presenta una nova definició de robustessa, incloent-hi una nova metodologia per avaluar-la. La robustessa estructural es relaciona amb la capacitat de l´estructura de mantenir nivells adequats de servei en front de nivells de dany creixents.S´analitza el nivell de funcionament d´estructures de formigó a mida que la corrosió de les armadures va creixent. Es defineixen indicadors de servei tant de tipus determinista com probabilista. Finalment, es presenta com exemple el cas d´un pont existent, que presenta nivells avançats de corrosió i se n´avaluen els index de robustessa

  • Structural behavior and design criteria for bridge strengthening by tied arch. Comparison with network arch bridges

     Valenzuela, Matías A.; Casas Rius, Joan Ramon
    International Conference on Arch Bridges
    p. 829-836
    Presentation's date: 2013-10-04
    Presentation of work at congresses

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    This study focuses on a new strengthening method of continuous bridges with several spans that present extensive damage in their foundation/piers due to scour and erosion. The method consists on the construction of a new upper steel arch with a network hanger's arrangement over the original deck with the aim to hang the existing deck to the new arch. The deck is acting as a tie in the new structural configuration. This allows to remove the damaged foundations/piers, deriving on an arch bridges with an span-length similar to the total length of the strengthened bridge and avoiding future problems related to scouring. The paper discusses about the resisting mechanisms that control the structural optimization process and therefore defines the design criteria. The main target of this process is different for each case, namely: the optimization of the arch in traditional network bridges; the limitation of maximum and minimum stresses in the deck in the case of strengthened bridges. Finally, it allows the comparison of each case, setting the differences between them and providing a new line of research on the topic of the tied arch method.

    This study focuses on a new strengthening method of continuous bridges with several spans that present extensive damage in their foundation/piers due to scour and erosion. The method consists on the construction of a new upper steel arch with a network hanger's arrangement over the original deck with the aim to hang the existing deck to the new arch. The deck is acting as a tie in the new structural configuration. This allows to remove the damaged foundations/piers, deriving on an arch bridges with an span-length similar to the total length of the strengthened bridge and avoiding future problems related to scouring. The paper discusses about the resisting mechanisms that control the structural optimization process and therefore defines the design criteria. The main target of this process is different for each case, namely: the optimization of the arch in traditional network bridges; the limitation of maximum and minimum stresses in the deck in the case of strengthened bridges. Finally, it allows the comparison of each case, setting the differences between them and providing a new line of research on the topic of the tied arch method.

  • Quantifying redundancy and robustness of structures

     Cavaco, E. S.; Casas Rius, Joan Ramon; Neves, L. A. C.
    Workshop on Safety, Failures and Robustness of Large Structures
    p. 78-99
    Presentation's date: 2013-02-15
    Presentation of work at congresses

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  • Introduction: robustness

     Faber, Michael Havbro; Vrouwenvelder, Ton; Casas Rius, Joan Ramon; Høj, Niels Peter
    Structural engineering international
    Vol. 22, num. 1, p. 66
    Date of publication: 2012-02
    Journal article

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  • Improved procedure for equivalent linearization of bridges supported on hysteretic isolators

     Jara, M.; Jara, J. M.; Olmos, B.A.; Casas Rius, Joan Ramon
    Engineering structures
    Vol. 35, p. 99-106
    DOI: 10.1016/j.engstruct.2011.10.028
    Date of publication: 2012-02
    Journal article

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  • Statistical analysis of existing models for flexural strengthening of concrete bridge beams using FRP sheets

     Ceci, Alfredo; Casas Rius, Joan Ramon; Ghosn, Michel
    Construction & building materials
    Vol. 27, num. 1, p. 490-520
    DOI: 10.1016/j.conbuildmat.2011.07.014
    Date of publication: 2012-02
    Journal article

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  • Monitoring, modelling and assessment of structural deterioration in marine environments

     Casas Rius, Joan Ramon; O'Connor, Alan
    Structure and infrastructure engineering
    Vol. 8, num. 6, p. 529-530
    DOI: 10.1080/15732479.2010.505373
    Date of publication: 2012-06
    Journal article

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  • Codes for safety assessment of existing bridges: current state and further development

     Wisniewski, Dawid; Casas Rius, Joan Ramon; Ghosn, Michel
    Structural engineering international
    Vol. 22, num. 4, p. 552-561
    DOI: 10.2749/101686612X13363929517857
    Date of publication: 2012-11
    Journal article

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    During the past decade, new codes for the assessment of existing bridges have been developed in Canada, the USA, as well as the UK, Denmark, and Switzerland. The practical application of these codes proved to be successful as they allowed for keeping in operation many bridges that no longer met the design criteria but were otherwise able to safely carry the applied loads. Because of the success of the national codes, the possibility of developing a new Eurocode for Bridge Safety Assessment is under consideration. Building on the experience from the various national codes and recent research, a bridge assessment Eurocode should specifically include the following key elements: (a) the possibility of directly using probability-based methods, (b) the inclusion of structural system redundancy and robustness criteria, (c) the use of site-specific live loads and dynamic amplification factors, (d) the incorporation of field measurements and diagnostic test data, and (e) the consideration of proof load testing. The objective of this paper is to review how the above-listed key elements are addressed in existing assessment codes and recommend possible improvements to current evaluation methods to be considered in the development of the new assessment Eurocode for bridges.

  • Caracterización estadística de los modelos de confinamiento y determinación de coeficientes parciales de seguridad para el refuerzo de pilas de puentes de hormigón mediante materiales compuestos (CFRP)  Open access

     Chambi Chuquichambi, José Luis
    Department of Strength of Materials and Structural Engineering, Universitat Politècnica de Catalunya
    Theses

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    El continuo deterioro y/o daños causados en las estructuras de hormigón durante su vida útil, son fenómenos inevitables que conlleva el paso del tiempo y viene a ser un problema importante que ha conducido al desarrollo de nuevos materiales compuestos para el refuerzo estructural. En el caso de puentes, las situaciones en las que se hacen necesarias intervenciones de refuerzo pueden ser: estructuras afectadas por patologías inherentes a problemas de durabilidad, estructuras mal proyectadas y/o mal ejecutadas, estructuras que han sido dañadas por causas externas (impacto de vehículos, incendio, sismo, desastres naturales, etc.), estructuras afectadas por un cambio de uso o por un aumento de la carga de proyecto, o para soportar futuros sismos. Frente a ello, los métodos de refuerzo tradicional tales como el recrecido de hormigón, postensado exterior y refuerzo con chapas de acero, frecuentemente tienen desventajas inherentes como el incremento del peso de la estructura, la corrosión del acero y su elevado costo de manipulación y colocación. Ante estos inconvenientes, y más concretamente refiriéndonos al refuerzo de pilas de puentes, en años recientes se ha incrementado el uso de polímeros reforzados con fibra (FRP) como elemento de confinamiento de elementos de hormigón sometidos a compresión, debido a sus excelentes propiedades mecánicas y químicas, incrementando principalmente la resistencia y ductilidad de las pilas de hormigón. Sin embargo, su aplicación presenta aún lagunas que exigen seguir investigando aspectos como la falta de códigos y normas, la falta de experiencia en el comportamiento a largo plazo, la susceptibilidad al fuego, etc. Existen incertidumbres en las bases de cálculo durante el dimensionamiento de este refuerzo, una de ellas está precisamente en los coeficientes parciales de seguridad para el hormigón confinado que se deben adoptar en el diseño. Por ello, la presente tesis doctoral pretende aportar conocimientos en este campo, y más concretamente, definiendo dichos coeficientes parciales de seguridad para el hormigón confinado para el diseño del refuerzo de pilas de puentes de hormigón armado con polímeros reforzados con fibras de carbono (CFRP), mediante proceso de calibración basado en fiabilidad estructural. En ese sentido, primeramente, se ha recopilado toda la información bibliográfica disponible referida principalmente a dos aspectos: descripción de modelos de confinamiento para hormigón confinado con CFRP y datos de ensayos experimentales para la elaboración de una base de datos. Los modelos de confinamiento considerados en este estudio para elementos de hormigón de sección circular son de: Mander et al. 1988, Pilakoutas y Mortazavi 1997, Toutanji 1999, Spolestra y Monti 1999, Eid y Paultre 2008, Teng et al. 2009, Wu y Zhou 2010. Aplicando las expresiones de predicción de estos modelos a los datos experimentales recogidos en la base de datos, obtenemos como resultado tensiones y deformaciones últimas, y con ellos, mediante un análisis estadístico de valores teóricos respecto a valores experimentales para cada modelo de confinamiento, y, tras un análisis comparativo entre los diferentes modelos definimos el modelo que mejor ajuste presenta respecto a los datos experimentales (modelo de Teng et al. 2009). Para dicho modelo, se ha realizado la caracterización estadística. Puesto que es poco probable esperar que un formato de norma de diseño estructural pueda representar todas las situaciones de diseño, los sistemas estructurales y tipologías de pilas de puentes para los cuales se ha realizado la calibración en este estudio, son los puentes de tramo recto de varios vanos con pilas de hormigón armado tipo columnas circulares. Las pilas pueden estar formadas por un fuste único o bien por dos fustes. Esta tipología de tablero y de pila cubre la mayor parte de los puentes existentes en las actuales vías de comunicación. Para definir los coeficientes parciales de seguridad para el hormigón confinado γcc, se ha realizado la calibración basado en fiabilidad estructural, para un rango posible de soluciones de refuerzo con CFRP en las tipologías de pilas de puentes de los sistemas estructurales estudiados. Para ello, se tienen en cuenta las incertidumbres de las variables que intervienen, y mediante simulación se caracterizan estadísticamente las variables de resistencia y solicitación. Teniendo caracterizadas estas dos variables, según los niveles requeridos de seguridad estructural se determina la probabilidad de fallo o índice de fiabilidad para diferentes valores de γcc. Los coeficientes parciales de seguridad quedarán definidos para aquellas situaciones, tales que, los índices de fiabilidad calculados en las pilas reforzadas dimensionadas con dichos coeficientes, den valores iguales o superiores al índice de fiabilidad objetivo, que en este estudio se ha fijado en . Finalmente, la propuesta de coeficientes parciales de seguridad a utilizar es la siguiente: γcc = 1,15 para tmín ≤ t ≤ 2 mm γcc = 1,30 para t > 2mm

    The continuous deterioration and/or damages caused in the concrete structures during their lifetime, are unavoidable phenomena which the passage of time entails and gets to be an important problem that it has led to the development of new composite materials used for the structural reinforcement. The methods of traditional reinforcement such as concrete increased, prestressed exterior and the reinforcement with steel sheets, frequently they have inherent disadvantages like the increase of the weight of the structure, the corrosion of the steel and its high cost of manipulation and positioning. Given these disadvantages, and more specifically referring us to the reinforcement of pillars of bridges, in recent years the use of fibre reinforced polymers (FRP) has increased as an element of confinement. However, its use still still shows some gaps which demand to continue investigating some of their aspects such as the lack of codes and rules, the lack of experience in the long term behaviour, the susceptibility to the fire, etc. Uncertainties exist in the calculation bases along the dimensioning of this reinforcement, one of them precisely lays in the partial coefficients of safety for the confined concrete that must be to adopted in the design. For this purpose, the present doctoral thesis tries to contribute knowledge in this field, and more specifically, defining these partial coefficients of safety of the confined concrete for the design of the reinforcement of bridge pillars of reinforced concrete with carbon fibre reinforced polymers (CFRP), by means of calibration process based on structural reliability. In this sense, firstly, has been compiled all the bibliographical information available mainly referred to two aspects: description of confinement models for confined concrete with CFRP and data obtained from experimental tests for the elaboration of a data base. Applying the prediction expressions of confinement models to the experimental data collected in the data base, we obtain as a result the stresses and strains ultimate, and from them, by means of a statistical analysis of theoretical values in respect to experimental values for each single model of confinement, and, after a comparative analysis between the different models we define the model that beste adjustment presents with respect to the experimental data (model of Teng et al.). For this model, the statistical characterization has been performed. Since it is unlikely to expect that a structural design frame rule may represent all the situations of design, the structural systems and typologies of bridge pillars for which the calibration has been performed in this study, are the bridges of straight section with several spans with reinforced concrete pillars of the type of circular columns. The pillars can be formed by a only fust or by two fusts. This typology of roadway and pillar covers most of the existing bridges in the current communication routes. In order to define the partial coefficients of safety for the confined concrete ¿cc, the calibration has been performed based on structural reliability, for a possible range of solutions of reinforcement with CFRP in the typologies of bridges pillars of the studied structural systems. For such a purpose, the uncertainties related of the variables which intervene have been taken into consideration, and by means of simulation the variables of strength and stress have been statistically characterized. Once these two variables have been characterized, according to the required levels of structural safety the probability of failure or reliability index for different values of ¿cc has been determined. The partial coefficients of safety will be defined for those situations, such that, the reliability indexes calculated in the reinforced pillars dimensioned with such coefficients, give results equal or higher than the objective reliability index, which has been established in ß=3,5 in this study.

    La contínua deterioració i/o danys causats en les estructures de formigó durant la seva vida útil, són fenòmens inevitables que comporta el pas del temps i es convertix en un problema important que ha conduït al desenvolupament de nous materials composts per al reforç estructural. En el cas de ponts, les situacions en les quals es fan necessàries intervencions de reforç poden ser: estructures afectades per patologies inherents a problemes de durabilitat, estructures mal projectades i/o mal executades, estructures que han estat danyades per causes externes (impacte de vehicles, incendi, sisme, desastres naturals, etc.), estructures afectades per un canvi d'ús o per un augment de la càrrega de projecte, o per suportar futurs sismes. Davant tot això, els mètodes de reforç tradicional tals com el recrescut de formigó, post tensat exterior i reforç amb xapes d'acer, freqüentment tenen desavantatges inherents com ara el increment del pes de l'estructura, la corrosió de l'acer i el seu elevat cost de manipulació i col·locació. Davant aquests inconvenients, i més concretament fent esment al reforç de pilars de ponts, en anys recents s'ha incrementat l'ús de polímers reforçats amb fibra (FRP) com a element de confinament d'elements de formigó sotmesos a compressió, a causa de les seves excel·lents propietats mecàniques i químiques, incrementant principalment la resistència i ductilitat de les pilars de formigó. No obstant això, la seva aplicació presenta encara punts foscos que exigeixen seguir investigant aspectes com la falta de codis i normes, la falta d'experiència en el comportament a llarg termini, la susceptibilitat al foc, etc. Existeixen incerteses a les bases de càlcul durant el dimensionament d'aquest reforç, una d'elles està precisament en els coeficients parcials de seguretat per al formigó confinat que s'han d'adoptar en el disseny. Per això, la present tesi doctoral pretén aportar coneixements en aquest camp, i més concretament, definint aquests coeficients parcials de seguretat per al formigó confinat per al disseny del reforç de pilars de ponts de formigó armat amb polímers reforçats amb fibres de carboni (CFRP), mitjançant procés de calibratge basat en fiabilitat estructural. En aquest sentit, primerament, s'han recopilat tota la informació bibliogràfica disponible referida principalment a dos aspectes: descripció de models de confinament per a formigó confinat amb CFRP i dades d'assajos experimentals per a l'elaboració d'una base de dades. Els models de confinament considerats en aquest estudi per a elements de formigó de secció circular són de: Mander et al. 1988, Pilakoutas i Mortazavi 1997, Toutanji 1999, Spolestra i Monti 1999, Eid i Paultre 2008, Teng et al. 2009, Wu i Zhou 2010. Aplicant les expressions de predicció d'aquests models a les dades experimentals recollides en la base de dades, obtenim com resultat tensions i deformacions últimes, i amb ells, mitjançant una anàlisi estadística de valors teòrics respecte a valors experimentals per a cada model de confinament, i, després d'una anàlisi comparativa entre els diferents models definim el model que millor ajust presenta respecte a les dades experimentals (model de Teng et al. 2009). Per a aquest model, s'ha realitzat la caracterització estadística. Ates que és poc probable esperar que un format de norma de disseny estructural pugui representar totes les situacions de disseny, els sistemes estructurals i tipologies de pilars de ponts pels quals s'ha realitzat el calibratge en aquest estudi, són els ponts de tram recte de diverses obertures amb pilars de formigó armat tipus columnes circulars. Les pilars poden estar formades per un fust únic o bé per dos fustos. Aquesta tipologia de tauler i de pilar cobreix la major part dels ponts existents en les actuals vies de comunicació. Per tal de definir els coeficients parcials de seguretat per al formigó confinat γcc, s'ha realitzat el calibratge basat en fiabilitat estructural, per a un rang possible de solucions de reforç amb CFRP en les tipologies de pilars de ponts dels sistemes estructurals estudiats. Per a això, es tenen en compte les incerteses de les variables que intervenen, i mitjançant simulació es caracteritzen estadísticament les variables de resistència i sol·licitació. Tenint caracteritzades aquestes dues variables, segons els nivells requerits de seguretat estructural es determina la probabilitat de fallada o índex de fiabilitat per a diferents valors de γcc. Els coeficients parcials de seguretat quedaran definits, per a aquelles situacions, tals que, els índexs de fiabilitat calculats en les pilars reforçades dimensionadas amb aquests coeficients donin valors iguals o superiors a l'índex de fiabilitat objectiu, que en aquest estudi s'ha fixat en β = 3,5. Finalment, la proposta de coeficients parcials de seguretat a utilitzar és la següent: γcc = 1,15 per a tmín ≤ t ≤ 2 mm

  • Verificación experimental de uniones mediante lazos de armadura y su aplicación en la construcción evolutiva de puentes  Open access

     Contreras Lopez, Catalina Del Pilar
    Department of Construction Engineering, Universitat Politècnica de Catalunya
    Theses

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    The box-girder is currently the solution for large prestressed concrete bridges, being most used today in steel and mixed structures. Their widespread use is due to the strength characteristics and versatility, using various construction processes depending on the conditions of the work. However, it has the great disadvantage that the concrete should be done in phases. Because of the advantages of this section is really important develop new techniques to improve the performance, and reduce construction times. The construction of the top slab involves extension straight joints. It has been observed that this kind of joint requires additional measures during execution, either from the point of view of the danger to operators or remove the inside formwork. As a result, it is needed propose a new type of joint, by loops, reducing risks, minimizing the construction times and making easier the work on site. To understand the behaviour of a structure with this loop joint, are built concrete sections with representative dimensions of a railway bridge, with a concrete joint, reproducing, as far as possible, what happens in reality. These sections will be tested experimentally. In a previous study has been analysed the performance in a simple bending test. For this reason, in this study is checked the response in pure bending. Dynamic and static campaigns are done, using for this a total of 8 slabs, existing three types of union based on European codes: - Reference Slab (LR) with a continuous reinforcement - DIN Slab (LD) with a loop joint according to DIN 1045 - Experimental Slab (LE) with the proposed loop joint With these results it is possible to know the performance until failure, under static and dynamics loads with a number of cycles of 2 x 10^6. In static load campaign are tested 3 slabs, representatives of the different types of continuity. With these results is possible to make a comparison between the behaviour of the slabs associated with: longitudinal and transverse strain, deflections and concrete joint opening. In dynamic load campaign are tested 5 slabs, three of them with the same type of reinforcement and the other two representatives of the others types. In each of these tests are applied different load ranges, depending on the objectives, defining 5 tests: 1. LR: ¿s=150 MPa --> Q_max=141 kN y Q_min=50 kN 2. LD: ¿s=150 MPa --> Q_max=141 kN y Q_min=50 kN 3. LE_2: ¿s=150 MPa --> Q_max=141 kN y Q_min=50 kN 4. LE_3: ¿s=150 MPa --> Q_max=210 kN y Q_min=119 kN 5. LE_4: ¿s=127 MPa --> Q_max=125 kN y Q_min=47 kN Based on the test load levels, are made comparisons between these results and the results obtained for an experimental slab under simple bending (L.F.S.), associated to: dynamic deflection, concrete joint opening, longitudinal and transverse strain, and failure loads after finished dynamic tests. Finally, are proposed futures research works, in order to increase the knowledge associated with a loop joint reinforcement under another type of efforts.

  • IABMAS senior Prize

     Casas Rius, Joan Ramon
    Award or recognition

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  • Bridge strengthening by network arch: structural performance and design criteria

     Valenzuela, Matías A.; Casas Rius, Joan Ramon
    International Conference on Bridge Maintenance, Safety and Management
    p. 1-8
    Presentation's date: 2012-07-09
    Presentation of work at congresses

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  • Refuerzo de puentes de luces medias por conversión en arco atirantado tipo network  Open access

     Valenzuela Saavedra, Matías Andrés
    Department of Construction Engineering, Universitat Politècnica de Catalunya
    Theses

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    Según estudios estadísticos a nivel mundial, una de las principales causas de fallos en puentes corresponde a problemas relacionados con la interacción entre estructura e hidráulica produciendo altos costos humanos y económicos. La mayoría de las patologías se relacionan con procesos de socavación y erosión en pilas y estribos, específicamente en las cimentaciones de las pilas, siendo necesario tomar medidas para su refuerzo. Las dificultades en la inspección y mantenimiento de la infraestructura, junto con la ineficiencia y elevados costos en la implementación de los refuerzos convencionales (pilotajes, recrecidos, entre otros) ha motivado al Departamento de Puentes, Ministerio de Obras Públicas de Chile, el desarrollo de una nueva técnica de refuerzo con el objetivo de eliminar la causa de la patología: las pilas y sus cimentaciones, focalizándose el estudio en puentes con tipología de viga continua de varios vanos de hormigón armado. La metodología propuesta considera el cambio estructural del puente incorporando arcos superiores atirantados con configuración de péndolas network y vertical encargados de levantar tablero y esfuerzos en el arco. A partir de ello, se verifica el comportamiento del refuerzo en etapas de construcción y posteriormente en estado de servicio mediante un análisis de las cargas de tráfico y accidentales (capítulo 5). Los resultados dan lugar a la sistematización del método de refuerzo alternativo propuesto, incluyendo la propuesta estructural y tecnológica, la factibilidad del proceso constructivo y, finalmente, un conjunto de criterios básicos de diseño para este tipo de refuerzos (capítulo 6). Finalmente, la validación estructural del método y un primer estudio económico de costes comparado respecto a otros métodos convencionales de refuerzo, entregan para futuros ingenieros un conjunto de criterios y recomendaciones básicas para la implementación de esta técnica. el tablero del puente original, el cuál, gracias a la aplicación de un pretensado exterior, actúa como tirante del sistema del arco, contrarrestando los empujes horizontales del mismo en los arranques. El levantamiento del tablero desde los soportes permite la demolición de éstos, reduciendo los riesgos relacionados con la interacción de la estructura con el flujo del cauce; además de reutilizar parte del puente original y entregar un nuevo concepto estético. Para determinar la factibilidad del método, se pone énfasis en el estudio del método constructivo a partir del proceso de tesado de las péndolas así como en su comportamiento en servicio posterior, teniendo en cuenta las solicitaciones sísmicas, de gran importancia en Chile. El proceso constructivo a plantear debe satisfacer dos requisitos fundamentales: evitar tensiones excesivas en el tablero para no superar las solicitaciones existentes en el puente original; y permitir un levantamiento total de la superestructura desde las pilas dañadas. El tener que mantener unos determinados niveles de tensión en el tablero original supone una complejidad adicional respecto a lo que sería el diseño y construcción de un puente arco tipo network totalmente nuevo. Nos encontramos pues ante un problema de optimización (orden y magnitud de las fuerzas de tesado para levantar el tablero) con fuertes condiciones de contorno (no superar los niveles máximos de esfuerzos en el tablero original). Frente a la complejidad del proceso de optimización multiobjetivo del proceso de tesado, se descarta el uso de una optimización manual (prueba y error), en favor de una metodología que combina el uso automatizado de programas de elementos finitos y métodos de optimización meta-heurísticos (algoritmos genéticos). Esta herramienta, desarrollada, calibrada y validada (capítulo 3), proporciona todo un conjunto de soluciones factibles del proceso constructivo. El algoritmo desarrollado se utiliza como herramienta para el estudio e implementación de esta metodología en dos puentes carreteros ubicados en la zona central de Chile, con tipología original de viga continua y con importantes problemas de socavación: San Luis (60 metros de longitud total distribuidos en cuatro vanos) y Puangue (72 metros de longitud total distribuidos en cuatro vanos). Mediante la aplicación práctica a estos dos puentes carreteros, se desarrolla un estudio paramétrico en etapa constructiva (capítulo 4), considerando como variables: el tipo de perfil del arco, la configuración de las péndolas network, entre otros, entregándose la influencia que tiene cada una de ellas en relación a la capacidad de levantamiento, admisibilidad de tensiones en el

    According to statistical studies worldwide, one of the main causes of damages in bridges correspond to problems related to the interaction between structure and hydraulic provoking high human and economic costs. Most pathology is related to processes of scour and erosion in piers and abutments, specifically in the foundations of the piers, being necessary to take strengthening measures. The difficulties in inspection and maintenance of infrastructure, and the inefficiency related to the high costs in the implementation of conventional strengthening methods (pile driving, screeds, etc.) has prompted the Department of Bridges, Ministry of Public Works of Chile, the development of a new method of strengthening in order to eliminate the cause of the pathology: the piers and its foundations, focusing the study on continuous bridges with several spans and cross-section of built up reinforced concrete beams plus an upper slab. The proposed methodology considers a structural change of bridge by the incorporation of upper arches with a network and vertical hangers arrangement, which, through the application of external prestressing, allows the system to behave as a bow tied, balancing the horizontal thrusts in its edges. The lifting of the deck from the supports via the vertical hangers allows their demolition, reducing the risks associated with the interaction of the structure with the river flow (scour), in addition to reuse the original bridge and deliver a new aesthetic. To determine the feasibility of the method, the study emphasizes on the construction method, specially on the process of tensioning of the hangers and their behaviour in service, considering the seismic loads, relevant in Chile. The construction process proposed must satisfy two fundamental requirements: to avoid excessive stress on the deck not to exceed the stresses existing in the original bridge or the maximum material strength and allowing a total lift of the superstructure from the damaged piers. Maintain certain level of stress on the original deck is an additional significant complexity, compared with the design and construction of a new network arch bridge. This derives on an optimization problem (order and magnitude of tensioning forces to lift the deck) with strong boundary conditions (not to exceed the maximum internal forces in the original deck). Given the complexity of multi-objective optimization of the tensioning process, the use of manual optimization (trial and error) is rejected, for a methodology that combines the use of automated finite element programs and methods of optimization meta-heuristics (genetic algorithms). This tool, developed, calibrated and validated (Chapter 3) provides a whole set of feasible solutions of the construction process. The algorithm developed is used as a tool for the study and implementation of this methodology on two highway bridges located in central Chile, with a original typology of continuous beam and important problems of scour: San Luis (60 meters total length in four spans) and Puangue (72 meters total length in four spans). Through the practical application of these two road bridges, a parametric study of the constructive stages is developed (Chapter 4), considering as variables: the arch profile, the network hangers arrangement, among others, giving the influence of each in relation to the lifting capacity, admissibility of stresses in the deck and internal forces in the arch. From this, the performance in construction and service stages is studied through an analysis of traffic and accidental loads (chapter 5). The results, lead to the systematization of the strengthening proposed method, including structural and technological proposals, the feasibility of the construction process and finally, a set of basic design criteria for this type of strengthening (Chapter 6). Finally, the structural validation of the method and a first economic study of costs compared to other conventional strengthening methods give a set of criteria and recommendations for the implementation of this technique.

    Segons estudis estadístics a nivell mundial, una de les principals causes de fallades en ponts correspon a problemes relacionats amb la interacció entre estructura i hidràulica produint alts costos humans i econòmics. La majoria de les patologies es relacionen amb processos de soscavació i erosió en piles i estreps, específicament en les fonamentacions de les piles, i caldrà prendre mesures per reforç. Les dificultats en la inspecció i manteniment de la infraestructura, juntament amb la ineficiència i elevats costos en la implementació dels reforços convencionals (pilotatges, recrescuts, entre altres) ha motivat al Departament de Ponts, Ministeri d'Obres Públiques de Xile, el desenvolupament de una nova tècnica de reforç amb l'objectiu d'eliminar la causa de la patologia: les piles i els seus fonaments, focalitzant l'estudi en ponts amb tipologia de biga contínua de diversos trams de formigó armat. La metodologia proposada considera el canvi estructural del pont incorporant arcs superiors atirantats amb configuració de pèndoles network i vertical encarregats d'aixecar el tauler del pont original, el qual, gràcies a l'aplicació d'un pretensat exterior, actua com tirant del sistema de l'arc, contrarestant les empentes horitzontals de la mateixa en les arrencades. L'aixecament del tauler des dels supports permet la demolició d'aquests, reduint els riscos relacionats amb la interacció de l'estructura amb el flux de la llera, a més de reutilitzar part del pont original i donar un nou concepte estètic. Per determinar la factibilitat del mètode, es posa èmfasi en l'estudi del mètode constructiu a partir del procés de tesat de les pèndoles així com en el seu comportament en servei posterior, tenint en compte les sol·licitacions sísmiques, de gran importància a Xile. El procés constructiu a plantejar ha de satisfer dos requisits fonamentals: evitar tensions excessives en el tauler per no superar les sol·licitacions existents en el pont original, i permetre un aixecament total de la superestructura des de les piles danyades. El haver de mantenir uns determinats nivells de tensió en el tauler original suposa una complexitat addicional respecte al que seria el disseny i construcció d'un pont arc tipus network totalment nou. Ens trobem doncs davant d'un problema d'optimització (ordre i magnitud de les forces de tesat per aixecar el tauler) amb fortes condicions de contorn (no superar els nivells màxims d'esforços en el tauler original). Davant la complexitat del procés d'optimització multiobjectiu del procés de tesat, es descarta l'ús d'una optimització manual (prova i error), a favor d'una metodologia que combina l'ús automatitzat de programes d'elements finits i mètodes d'optimització meta-heurístics (algorismes genètics). Aquesta eina, desenvolupada, calibrada i validada (capítol 3), proporciona tot un conjunt de solucions factibles del procés constructiu. El algorisme desenvolupat s'utilitza com a eina per a l'estudi i implementació d'aquesta metodologia en dos ponts carreters ubicats a la zona central de Xile, amb tipologia original de biga contínua i amb importants problemes de soscavació: Sant Lluís (60 metres de longitud total distribuïts en quatre obertures) i Puangue (72 metres de longitud total distribuïts en quatre obertures). Mitjançant l'aplicació pràctica a aquests dos ponts carreters, es desenvolupa un estudi paramètric en etapa constructiva (capítol 4), considerant com a variables: el tipus de perfil del arc, la configuració de les pèndoles network, entre altres, lliurant la influència que té cada una d'elles en relació a la capacitat d'aixecament, admissibilitat de tensions en el tauler i esforços en l'arc. A partir d'això, es verifica el comportament del reforç en etapes de construcció i posteriorment en estat de servei mitjançant una anàlisi de les càrregues de trànsit i accidentals (capítol 5). Els resultats donen lloc a la sistematització del mètode de reforç alternatiu proposat, inclosa la proposta estructural i tecnològica, la factibilitat del procés constructiu i, finalment, un conjunt de criteris bàsics de disseny per a aquest tipus de reforços (capítol 6). Finalment, la validació estructural del mètode i un primer estudi econòmic de costos comparat respecte a altres mètodes convencionals de reforç, lliuren per a futurs enginyers un conjunt de criteris i recomanacions bàsiques per a la implementació d'aquesta tècnica.

  • Robustness assessment of a corroded RC bridge deck

     Cavaco, E. S.; Neves, L. A. C.; Casas Rius, Joan Ramon
    International Conference on Bridge Maintenance, Safety and Management
    p. 1-8
    Presentation's date: 2012-07-09
    Presentation of work at congresses

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  • Redundancy of highway bridge decks

     Anitori, Giorgio; Casas Rius, Joan Ramon; Ghosn, Michel
    International Conference on Bridge Maintenance, Safety and Management
    p. 1-8
    Presentation's date: 2012-07-09
    Presentation of work at congresses

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  • 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.

  • Redundancy evaluation of integral bridges under lateral loads and effect of FRP reinforcement on system behavior

     Anitori, Giorgio; Casas Rius, Joan Ramon
    International Association for Bridge and Structural Engineering Symposium
    p. 92-93
    Presentation's date: 2012-09-18
    Presentation of work at congresses

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  • Application of OBR fiber optic technology in the structural health monitoring of the Can Fatjó viaduct (Cerdanyola del Vallé-Spain)

     Villalba Herrero, Vicente; Villalba Herrero, Sergio; Casas Rius, Joan Ramon
    International Conference on Bridge Maintenance, Safety and Management
    p. 1-8
    Presentation's date: 2012-07-11
    Presentation of work at congresses

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  • Evaluation of bridge redundancy under lateral loads

     Anitori, Giorgio; Casas Rius, Joan Ramon; Ghosn, Michel
    International Conference on Bridge Maintenance, Safety and Management
    p. 1-8
    Presentation's date: 2012-07-10
    Presentation of work at congresses

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  • Enhancement of bridge redundancy to lateral loads by FRP strengthening

     Anitori, Giorgio; Casas Rius, Joan Ramon; Ghosn, Michel; Jurado, S.
    International Conference on Bridge Maintenance, Safety and Management
    p. 1-8
    Presentation's date: 2012-07-10
    Presentation of work at congresses

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  • Access to the full text
    Reliability-based assessment of masonry arch bridges  Open access

     Casas Rius, Joan Ramon
    Construction & building materials
    Vol. 25, num. 4, p. 1621-1631
    DOI: 10.1016/j.conbuildmat.2010.10.011
    Date of publication: 2011-04
    Journal article

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    The paper presents a methodology for the probabilistic assessment of masonry arches at the serviceability and ultimate limit states. First, it explains the definition of the different failure modes and corresponding limit state functions that may occur depending on the type of masonry construction (single-ring and multi-ring). The most reported modes of failure are the four-hinge mechanism, the ring separation in multiring arches and the slippage at the foundations. Because of the lack of reliable material data (in the statistic sense) or available response models, only those more prone to be analyzed using reliability-based methods are shown in this paper: four-hinge mechanism and ring separation. The possibility of fatigue failure of masonry arch bridges under service loads and the proposal of reliability-based assessment methods at the ultimate level of the 4 hingemechanism are also analyzed. Finally, the proposed methodology is applied to an existing bridge.

    Postprint (author’s final draft)

  • Aplicación de criterios de robustez estructural para la ampliación de la vida útil de puentes existentes

     Ramos Schneider, Gonzalo; Aparicio Bengoechea, Angel Carlos; Valenzuela Saavedra, Andrés; Chambi Chuquichambi, José Luis; Casas Rius, Joan Ramon
    Competitive project

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  • Monitorización continua-gestión estructural: monitorización del viaducto de la carretera BP-1413 (Cerdanyola del Vallés)

     Villalba Herrero, Vicente; Casas Rius, Joan Ramon
    Congreso de la Asociación Científico-Técnica del Hormigón Estructural
    Presentation's date: 2011-10-27
    Presentation of work at congresses

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    Se presenta la aplicación en un viaducto de un sistema de monitorización continúo (en el espacio y tiempo) de fibra óptica (OBR) que suministra datos a tiempo real para poder controlar y conocer el estado/comportamiento de la estructura. Se confirma la viabilidad del pegado de los 100m de fibra óptica sobre la superficie de hormigón y la lectura continua durante el periodo de investigación. Se obtienen lecturas de deformación y se comparan con las obtenidas en las pruebas de carga realizadas, confirmando la precisión de la tecnología (+-1 με). Gracias a esta precisión y a una resolución espacial de 10 με, el sistema propuesto aporta ventajas importantes respecto a otros equipos de monitorización de fibra óptica. La medición continua de deformaciones a lo largo de toda la longitud de la fibra permite además obtener las flechas. Se presentan los resultados obtenidos de la monitorización a tiempo real, como también futuras aplicaciones del sistema en otras obras de ingeniería civil y edificación.

  • Safety factors in the strengthening to flexure with CFRP of concrete bridges

     Casas Rius, Joan Ramon; Ghosn, Michel; Ceci, Alfredo
    Congreso Nacional de Materiales Compuestos
    p. 795-800
    Presentation's date: 2011-07-05
    Presentation of work at congresses

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  • Bridge strengthening by structural change: optimization via genetic algorithm

     Valenzuela, Matías A.; Casas Rius, Joan Ramon
    International Conference on Space Structures
    Presentation's date: 2011-09-20
    Presentation of work at congresses

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    This paper presents a detailed study of the construction and cable-stressing process for the strengthening of bridges by the conversion of the structural typology from continuous beams to tied-arch bridges. The basic stages of the construction method and the basic assumptions of the study and applications of stress method, based on automated optimization using genetic algorithms, are described. Additionally, a criterion of design variables, constraints and objective functions are defined. Finally, an example of application to the San Luis Bridge in Chile is presented and illustrates the use of the algorithm.

  • Vibration based criteria for damage control in bridge structures

     Rodrigues, J. Fernando; ALFONSO DE OLIVEIRA ALMEIDA, PEDRO; Casas Rius, Joan Ramon
    International Conference on Space Structures
    Presentation's date: 2011-09-22
    Presentation of work at congresses

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  • Fibrous materials reinforced composites for structural health monitoring

     Güemes, Alfredo; Casas Rius, Joan Ramon
    Date of publication: 2011-04
    Book chapter

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    Structural Health Monitoring is becoming more and more used in civil engineering infrastructure. The technology for implementing SHM applications is presented in this Chapter. Details on instrumented civil constructions are then discussed, together with most innovative future trends.

  • Verificación experimental de uniones mediante lazos de armadura y su aplicación en la construcción evolutiva de puentes

     Contreras, Catalina P.; Casas Rius, Joan Ramon; Aparicio Bengoechea, Angel Carlos
    Congreso de la Asociación Científico-Técnica del Hormigón Estructural
    Presentation's date: 2011-10-26
    Presentation of work at congresses

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    El presente trabajo entrega un estudio a partir de ensayos de un nuevo tipo de empalme para puentes de sección cajón construidos evolutivamente, buscando reducir riesgos asociados a la construcción y plazos de ejecución. Por esta razón se realizan ensayos de rotura en losetas de hormigón armado, estableciendo una comparación de resultados para el empalme experimental con otras losetas de armadura continua y empalme mediante lazos establecido en DIN 1045. Se entregan los resultados de carga de rotura, deformaciones en la armadura, flechas y abertura de junta de hormigonado para un ensayo de flexión pura. Se plantean las metodologías de ensayo y se entrega un primer ensayo a fatiga, esperando concluir en futuros trabajos acerca del comportamiento frente a este fenómeno en las diferentes losetas.

  • Diseño y validación experimental de uniones mediante superposición con lazos en viaductos de hormigón de sección transversal evolutiva

     Villalba Herrero, Sergio; Aparicio Bengoechea, Angel Carlos; Casas Rius, Joan Ramon
    Congreso de la Asociación Científico-Técnica del Hormigón Estructural
    Presentation's date: 2011-10-26
    Presentation of work at congresses

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    En este trabajo se estudia el diseño y la posterior validación experimental de una unión estructural de longitud limitada, basada en la superposición a través de lazos de armaduras yuxtapuestas, confinadas en su interior mediante armadura transversal, para materializar el enlace de dos elementos estructurales ejecutados en distintas fases de hormigonado. En la presente investigación se analiza la respuesta y el comportamiento frente a flexión simple de 16 losas de hormigón armado, cuya totalidad, engloban dos campañas experimentales, una primera frente a carga estática, seguida de una segunda frente a carga cíclica. Los parámetros de longitud total del lazo proyectado y del diámetro empleado son analizados y comparados frente a la capacidad última resistente. Asimismo, los valores obtenidos son cotejados con los obtenidos mediante las losas de referencia (sin dispositivo de unión) para validar su aplicabilidad.

  • Experimental verification of construction joints by reinforcement loops

     Contreras, Catalina P.; Aparicio Bengoechea, Angel Carlos; Casas Rius, Joan Ramon
    International Conference on Space Structures
    Presentation's date: 2011-09-21
    Presentation of work at congresses

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    The present work delivers one experimental study of a new type of joint reinforcement for boxgirder bridges constructed evolutionarily, seeking to reduce execution time, improve formwork placement inside the box section, and minimize work risks. For this reason, failure tests are carried out in reinforced concrete slabs, comparing the experimental results of proposed joint with continuous reinforcement and a loop union according to DIN 1045. The results are delivered in terms of resistance, deflection and concrete joint opening for a pure bending test. They are also included the results of a fatigue test, waiting to conclude in the next future the work about the behaviour of different concrete slabs.