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UPCommons - E-prints UPC Universitat Politècnica de Catalunya (78,620 recursos)
E-prints UPC cobreix dues finalitats: per una banda, és el dipòsit institucional de la UPC que recull els articles de revista, les comunicacions de congrés i els reports de recerca generats en les activitats de recerca del personal docent i investigador de la universitat; per l'altra, és una eina que permet accelerar la producció científica, allotjant versions de documents prèvies a la publicació en una revista o a les actes d’un congrés.

Articles de revista

Mostrando recursos 1 - 20 de 177

1. Efficient 1D model for blind assessment of existing bridges : simulation of a full scale loading test and comparison with higher order continuum models - Santos Ferreira, Denise Carina; Bairán García, Jesús Miguel; Marí Bernat, Antonio Ricardo
Assessing the structural performance of existing concrete bridges is nowadays a major task. Nonlinear finite element (FE) analysis can quantify their capacity, evaluate strengthening interventions and prevent premature dismantle. However, this technique, mainly performed with 2D/3D FE, is seldom used at true scale due to the great complexity and computational costs involved. In this paper, the loading test of a strengthened concrete bridge in Sweden (Örnsköldsvik) is simulated using a 1D model. The bridge failed in combination of shear–bending–torsion triggered by fibre-reinforced polymer bond failure. Consecutive levels of refinement of the 1D model are presented and available results from higher...

2. The bridges of the future or the future of bridges? - Casas Rius, Joan Ramon
Postprint (author’s final draft)

3. External sulfate attack in dam concretes with thaumasite formation - Chinchón Payá, S.; Aguado de Cea, Antonio; Nugteren, H. W; Chinchón Yepes, Jose Servando
Concrete core samples extracted from different areas of the Mequinenza Dam (Spain) have been studied and expansive reactions affecting the structure were not found. However, expansive reactions in the concrete of certain parts located near the abutments of two galleries have been observed as a consequence of an external sulfate attack due to the sulfur compounds contained in the lignites that are present on the surrounding terrain. Secondary gypsum, ettringite, and thaumasite, as well as several sulfate efflorescence have been detected. The thaumasite formed in the degraded concrete is related to a Thaumasite Sulfate Attack (TSA). Scanning Electron Microscopy (SEM)...

4. Safety factors for CFRP strengthening in bending of reinforced concrete bridges - Trentin, Caterina; Casas Rius, Joan Ramon
Concerning the strengthening in bending of reinforced concrete bridge decks, the use of fiber reinforced polymers (FRP) has increased 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 reinforced concrete bridge decks. To try to...

5. Passive and hybrid mitigation of potential near-fault inner pounding of a self-braking seismic isolator - Abdel Kareem Moustafa, Mohamed Ismail; Rodellar Benedé, José; Pozo Montero, Francesc
A seismic isolated structure is usually a long-period structural system, which may encounter a low-frequency resonance problem when subjected to a near-fault earthquake that usually has a long-period pulse-like waveform. This long-period wave component may result in an enlargement of the base displacement and a decrease of the isolation efficiency. To overcome this problem, a rolling-based seismic isolator, referred to as roll-n-cage (RNC) isolator, has been recently proposed. The RNC isolator has a built-in buffer (braking) mechanism that limits the peak isolator displacements under severe earthquakes and prevents adjacent structural pounding. This paper addresses the problem of passive and hybrid...

6. Design of FRC tunnel segments considering the ductility requirements of the Model Code 2010 - Liao, Lin; Fuente Antequera, Albert de la; Pialarissi Cavalaro, Sergio Henrique; Aguado de Cea, Antonio
Fibre reinforced concrete (FRC) is used to improve the mechanical response of precast segments for tunnels. The structural use of the material has been regulated by national codes and, recently, by the Model Code 2010 (MC 2010, hereinafter). In this regard, it is necessary to update the philosophy applied to the design of tunnel segments in compliance with the most recent guidelines, evaluating their applicability and repercussion. The objective of this paper is to present a critical analysis of the design of FRC segments according to the ductility requirements from the MC 2010; an alternative approach is proposed that is...

7. Efficient preliminary floating offshore wind turbine design and testing methodologies and application to a concrete spar design - Matha, Denis; Sandner, Frank; Molins i Borrell, Climent; Campos Hortigüela, Alexis; Cheng, Po Wen
The current key challenge in the floating offshore wind turbine industry and research is on designing economic floating systems that can compete with fixed-bottom offshore turbines in terms of levelized cost of energy. The preliminary platform design, as well as early experimental design assessments, are critical elements in the overall design process. In this contribution, a brief review of current floating offshore wind turbine platform pre-design and scaled testing methodologies is provided, with a focus on their ability to accommodate the coupled dynamic behaviour of floating offshore wind systems. The exemplary design and testing methodology for a monolithic concrete spar...

8. Pull-out of textile reinforcement in concrete - Williams Portal, Natalie; Fernández Pérez, Ignasi; Nyholm Thrane, Lars; Lundgren, Karin
Textile Reinforced Concrete (TRC) has emerged as a promising novel alternative offering corrosion resistance and both thinner and light-weight structures. Although TRC has been extensively researched, the formalization of experimental methods and design standards is still in progress. The aim of this work was to extract local-bond behaviour from pull-out tests of basalt and carbon TRC and utilize these in both simple (1D) and advanced models (3D) to yield the global structural behaviour. The simulation results from the 1D and 3D models are able to simulate the complex behaviour of TRC with a reasonable level of correlation. (C) 2014 Elsevier...

9. Environmental impacts related to the commissioning and usage phase of an intelligent energy management system - Gangolells Solanellas, Marta; Casals Casanova, Miquel; Forcada Matheu, Núria; Macarulla Martí, Marcel; Giretti, Alberto
This paper presents for the first time the results of a life cycle assessment study for an intelligent energy management system. We considered material acquisition, manufacturing, transportation, assembly, operation and maintenance stages. The results show that the assembly phase had an environmental impact of 897 Eco-indicator 99 points that was mainly due to the monitoring subsystem (87.80%). When the analysis was extended to cover the use phase, the environmental impact ranged from 1963 (useful life of 5 years) to 3029 Eco-indicator 99 points (useful life of 10 years). The environmental impact of the use stage was found to represent 54–70%...

10. Cracking assessment in concrete structures by distributed optical fiber - Rodríguez, Gerardo; Casas Rius, Joan Ramon; Villalba Herrero, Sergi
In this paper, a method to obtain crack initiation, location and width in concrete structures subjected to bending and instrumented with an optical backscattered reflectometer (OBR) system is proposed. Continuous strain data with high spatial resolution and accuracy are the main advantages of the OBR system. These characteristics make this structural health monitoring technique a useful tool in early damage detection in important structural problems. In the specific case of reinforced concrete structures, which exhibit cracks even in-service loading, the possibility to obtain strain data with high spatial resolution is a main issue. In this way, this information is of...

11. Empirical approach for real-time estimation of air flow rates in a subway station - Di Perna, Costanzo; Carbonari, Alessandro; Ansuini, Roberta; Casals Casanova, Miquel
The EU-funded project called SEAM4US (Sustainable Energy mAnageMent for Underground Stations) is targeted to define advanced control systems for cost-effective management of subway stations, which will be applied to the pilot

12. Analysis of the implementation of effective waste management practices in construction projects and sites - Gangolells Solanellas, Marta; Casals Casanova, Miquel; Forcada Matheu, Núria; Macarulla Martí, Marcel
In this paper, the implementation of effective waste management practices in construction projects and sites is analyzed, using data from a survey answered by 74 Spanish construction companies based in Catalonia. Most commonly implemented practices were found to be on-site cleanliness and order, correct storage of raw materials, and prioritization of the nearest authorized waste managers. The least widespread practices were the use of a mobile crusher on site, the creation of individualized drawings for each construction site, and the dissemination of the contents of the waste management plan to all workers, to help them to meet its requirements. Waste...

13. Development of an integrated remote monitoring technique and its application to para-stressing bridge system - Miyamoto, Ayaho; Motoshita, Minoru; Casas Rius, Joan Ramon
Bridge monitoring system via information technology is capable of providing more accurate knowledge of bridge performance characteristics than traditional strategies. This paper describes not only an integrated Internet monitoring system that consists of a stand-alone monitoring system (SMS) and a Web-based Internet monitoring system (IMS) for bridge maintenance but also its application to para-stressing bridge system as an intelligent structure. IMS, as a Web-based system, is capable of addressing the remote monitoring by introducing measuring information derived from SMS into the system through Internet or intranet connected by either PHS or LAN. Moreover, the key functions of IMS such as...

14. Review of the use of phase change materials (PCMs) in buildings with reinforced concrete structures - Pons Valladares, Oriol; Aguado de Cea, Antonio; Fernández, Ana Inés; Cabeza, Luisa; Chimenos, Josep Maria
Phase change materials are capable of storing and releasing energy in the form of heat in determined temperature ranges, so to increase a building's thermal inertia, stabilize its indoor temperatures and reduce its energetic demand. Therefore, if we used these materials we could have more energetically efficient buildings. Nevertheless, are these materials most appropriate to be used in buildings? Could the incorporation of phase change materials in buildings with concrete structures be generalized? This article aims to carry out a review of these phase change materials from construction professionals' points of view, study their applications for buildings with reinforced concrete...

15. Rheology of fresh concretes with recycled aggregates - Faleschini, Flora; Jiménez Fernández, Cristian Gonzalo; Barra Bizinotto, Marilda; Aponte Hernández, Diego Fernando; Vázquez Ramonich, Enric; Pellegrino, Carlo
The most frequently used measure of rheology is the slump test, which evaluates workability. Since this value is often operator-sensitive, a more quantitative estimate can be derived in terms of fundamental physical quantities, such as plastic viscosity and yield stress. The higher heterogeneity in terms of experimental slump measure occurs when recycled aggregate concrete (RAC) is tested. In this work, 16 recycled mixes were analysed with two aggregates proportioning methods and results were compared with four controls: rheological parameters were measured with a ConTec BML Viscometer 3. The results represent a valid tool for better understanding of fresh RAC rheology.

16. Numerical analysis of structural damage in the church of the Poblet Monastery - Saloustros, Savvas; Pelà, Luca; Roca Fabregat, Pedro; Portal, Jorge
Identifying the possible causes of existing damage in historical structures is a complex task. Common difficulties are the limited information regarding the history of the construction, the properties of materials and the morphology of structural members. This paper investigates the capability of advanced numerical modelling to address the aforementioned issues and to simulate the damage in complex masonry structures. The case under study is the church of the Poblet Monastery, one of the UNESCO World Heritage Sites in Spain. The developed finite element model includes the actual-deformed 3D geometry of a selected bay, aiming to consider the important deformation of the...

17. Shear strain influence in the service response of FRP reinforced concrete beams - Santos Ferreira, Denise Carina; Oller Ibars, Eva; Torres Llinàs, Lluis; Barris Peña, Cristina
Shear strains can become significant in the response of RC beams, especially in the case with longitudinal FRP reinforcement. The effect of the shear strains is studied in this paper through the numerical results of a 1D non-linear fibre model accounting for the axial–bending–shear interaction. Experimental data from FRP RC beams, tested by the authors, are compared with the numerical results determined with the shear-sensitive and with a pure flexural 1D model in order to evaluate the effect of shear. A good correlation in terms of ultimate loads, deflections, strains in the concrete and reinforcement was observed between the experimental...

18. Evolution of pyrrhotite oxidation in aggregates for concrete - Oliveira da Silva, Izelman; Pialarissi Cavalaro, Sergio Henrique; Aguado de Cea, Antonio
Rocks containing pyrrhotite bands are sometimes used to produce concrete. These rocks oxidize and produce long-term expansive reactions that damage concrete structures, leading to important economic and risk related repercussions. The present study analyses several aspects that affect the oxidation process of the aggregate such as the existence of preferential paths for the entrance of the oxidizing agent and the conversion process of the chemical elements involved in the reaction. For that, host rock samples containing pyrrhotite were investigated by scanning electron microscopy and energy dispersive spectroscopy. The results shows that the pyrrhotite appears in bands that create planes of...

19. Vigas armadas híbridas de acero: estado del conocimiento - Chacón Flores, Rolando Antonio
Una viga armada se considera híbrida cuando se utilizan diferentes límites elásticos de acero en las chapas de alas y alma que la conforman. Un diseño estructural de una viga armada híbrida puede resultar más eficiente que el de una viga homogénea, tanto desde un punto de vista resistente como desde un punto de vista económico y sostenible. Para una capacidad a flexión dada, se utilizarán chapas de acero de viga armada de menor espesor que su equivalente de viga homogénea. Las vigas armadas híbridas han sido estudiadas a nivel teórico, experimental y numérico bajo solicitaciones de flexión, de inestabilidad...

20. Nonlinear analysis of RC beams using a hybrid shear-flexural fibre beam model - Santos Ferreira, Denise Carina; Bairán García, Jesús Miguel; Marí Bernat, Antonio Ricardo; Faria, Rui
Purpose: A nonlinear finite element (FE) beam-column model for the analysis of reinforced concrete (RC) frames with due account of shear is presented in this paper. The model is an expansion of the traditional flexural fibre beam formulations to cases where multiaxial behaviour exists, being an alternative to plane and solid FE models for the nonlinear analysis of entire frame structures. The paper aims to discuss these issues. Design/methodology/approach: Shear is taken into account at different levels of the numerical model: at the material level RC is simulated through a smeared cracked approach with rotating cracks; at the fibre level, an...

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