Metodología para el cálculo de los cimientos de una máquina rotativa que soporta cargas dinámicas incluido el arranque transitorio

[EN] Often engineers solve problems in relationship with structures and foundations from the point of view of structural statics. Nothing so far of the reality when finally, on the structure or the foundation, is installed a machine. Loads produced by machines change with time and will not be constant. The parts that made a machine are usually moving and they transmit to the structure dynamics loads which change with time. Thinking in dynamics loads means consider the variable ¿time¿ to calculate a foundation or a structure. A part of the energy wasted by the machine is transformed in radiation from the vibration of the machine and transmitted to the soil (Richart et al., 1970). During the transient to get the nominal speed of the machine, the system can cross its ¿natural frequency¿ and collapse by an excess of amplitude of vibration (Richart et al., 1970; Arya et al., 1979; Chowdhury & Dasgupta, 2009). D¿Alambert differential equations based in the Lysmer¿s analogy (Lysmer & Richart, 1966) were applied in the time domain to study the vertical movement, sliding and rocking (Barkan, 1962) of the ensemble foundation ¿ inertial block ¿ machine. Equations differentials were integrated with a time-step scheme (Chowdhury & Dasgupta, 2009), the Newmark¿s ß method (Newmark, 1959), getting the amplitude of vibration, speed, acceleration and strength in the transient and in the permanent operation mode. Methodology was applied to a rotary machine working at 3.000 r.pm. with an inertial block and a block foundation, a 3-mass problem with 37 variables. The ground, its parameters and impedance are calculated applying the Norma ACI 351.3R-04 (2004). Dynamic loads were calculated in accordingto ACI Norm 351.3R-04, API Norms Standard 613 (Arya et al., 1979) and ISO Norm 1940/1 (2003). A MATLAB program was developed to solve the D¿Alambert differential equations and get the amplitude of vibration, speed, acceleration and strength changing the speed of the machine during the first 3.000 seconds since 0 to 3.000 seconds with different starting functions (Rodriguez et al., 2010). Random solutions of the 37 variables were generated by the program. The program allowed to fix constraints to the solution calculated. A set of rules were applied to the transient and the permanent operation mode of the machine (Rodriguez et al., 2010). Limits, extracted from the ISO Norm, of the amplitude of vibration, speed, acceleration and strength in the transient and in the permanent operation mode were applied to get the right solution. Finally, this methodology permits to applied metaheuristics to optimize the cost of the foundation.[ES] A menudo, los ingenieros resuelven problemas en relación con estructuras y cimientos desde el punto de vista de la estática estructural. Nada tan lejos de la realidad cuando finalmente, en la estructura o los cimientos, se instala una máquina. Las cargas producidas por las máquinas cambian con el tiempo y no serán constantes. Las partes que formaron una máquina generalmente se mueven y transmiten a la estructura cargas dinámicas que cambian con el tiempo. Pensar en cargas dinámicas significa considerar la variable "tiempo" para calcular una base o una estructura. Una parte de la energía desperdiciada por la máquina se transforma en radiación de la vibración de la máquina y se transmite al suelo (Richart et al., 1970). Durante el transitorio para obtener la velocidad nominal de la máquina, el sistema puede cruzar su "frecuencia natural" y colapsar por un exceso de amplitud de vibración (Richart et al., 1970; Arya et al., 1979; Chowdhury & Dasgupta, 2009). Las ecuaciones diferenciales de D'Alambert basadas en la analogía de Lysmer & Richart (1966) se aplicaron en el dominio del tiempo para estudiar el movimiento vertical, deslizamiento y balanceo (Barkan, 1962) de la base del conjunto - máquina de bloque inercial. Las ecuaciones diferenciales se integraron con un esquema de pasos de tiempo (Chowdhury & Dasgupta, 2009), el método ß de Newmark (1959), obteniendo la amplitud de vibración, velocidad, aceleración y fuerza en el modo de operación transitoria y permanente. La metodología se aplicó a una máquina rotativa que funciona a 3.000 r.pm. con un bloque inercial y una base de bloque, un problema de 3 masas con 37 variables. El suelo, sus parámetros e impedancia se calculan aplicando la Norma ACI 351.3R-04 (2004). Las cargas dinámicas se calcularon de acuerdo con la norma ACI 351.3R-04, las normas API estándar 613 (Arya et al., 1979) y la norma ISO 1940/1 (2003). Se desarrolló un programa MATLAB para resolver las ecuaciones diferenciales D¿Alambert y obtener la amplitud de vibración, velocidad, aceleración y fuerza cambiando la velocidad de la máquina durante los primeros 3.000 segundos desde 0 a 3.000 segundos con diferentes funciones de arranque (Rodriguez et al., 2010). El programa generó soluciones aleatorias de las 37 variables. El programa permitió corregir restricciones a la solución calculada. Se aplicó un conjunto de reglas al modo de operación transitorio y permanente de la máquina (Rodriguez et al., 2010). Los límites, extraídos de la Norma ISO, de la amplitud de vibración, velocidad, aceleración y fuerza en el modo de operación transitoria y permanente se aplicaron para obtener la solución correcta. Finalmente, esta metodología permite aplicar metaheurísticas para optimizar el costo de la fundaciónTerradez Marco, JL.; Hospitaler Pérez, A. (2020). A methodology for the calculation of the foundation of a rotary machine supporting dynamic loads including the transient starting. Anales de Edificación. 6(1):12-23. https://doi.org/10.20868/ade.2020.4450S12236

Diseño prestacional de túneles en situación de incendios. Modelos FDS. Aplicación a un túnel de metro

[ES] El objeto del presente trabajo final de máster consiste en la aplicación de la metodología del diseño prestacional para la definición de un sistema de ventilación de emergencia en caso de incendio en un túnel de metro. Se recurre a esta metodología ya que no es posible realizar el diseño del sistema de ventilación de emergencia basándose en las prescripciones normativas. En primer lugar se realiza una introducción a la problemática de los incendios en túneles donde se definen motivación, objeto, alcance, objetivos y una introducción a la metodología basado en prestaciones o eficacia que es la adoptada para la elaboración del presente trabajo final de master (TFM). Posteriormente se realiza una introducción histórica de los túneles realizados por el hombre, las tipologías de túneles, sus secciones y sus usos. También se definen los elementos de una sección y las instalaciones de los túneles ferroviarios. Para ello se aborda como los diferentes modelos de la curva de tasa de liberación de calor en túneles de metro a lo largo de la historia, partiendo de modelos empíricos hasta los actuales modelos computacionales. También se analiza la obtención de otros parámetros de los modelos de incendio en túneles como la producción de productos tóxicos derivados de la combustión de la carga de fuego en el interior del túnel. Para abordar el problema se estudiarán métodos de modelado de los escenarios de incendio, centrándose en los modelos de campo y en particular en el software FDS. Una vez definido el software a emplear, se realiza un estudio sobre la ventilación en túneles en particular en túneles de metro. Se estudiarán diferentes sistemas de ventilación de emergencia empleado en túneles. Para abordar el diseño de la instalación de ventilación de emergencia se definirán los conceptos de velocidad crítica y backlayering y se aplicarán para la realización de un diseño de prueba. Se analizará también el modelado del sistema de ventilación elegido para el túnel mediante el software FDS y se realizará un predimensionado de la instalación de ventilación de emergencia. Por otra parte se definen los conceptos ASET (Available Safety Egress Time) y RSET (Required Safety Egress Time) y se proponen diferentes métodos para el cálculo del RSET eligiéndose el método propuesto por la Guía Europea CFPA No. 19 basado en una simulación computacional. Para realizar esta simulación se empleará el software Pathdinder, explicándose se utilización y se generará un modelo de evacuación. Finalmente se empleará la formulación prestacional del problema de seguridad en caso de incendio en túneles aplicándolo al caso de una línea de metro ejemplo empleando todos los conceptos introducidos mediante un caso práctico.Hospitaler Pérez, A. (2016). Diseño prestacional de túneles en situación de incendios. Modelos FDS. Aplicación a un túnel de metro. http://hdl.handle.net/10251/73383.TFG

Analysis of the fire resistance of timber jack arch flooring systems used in historical buildings

[EN] Conservation of built heritage, at present, is a major task and a great challenge because it requires adapting the performance of existing buildings to current code requirements, when very often these were built before codes existed. Timber jack arch flooring systems can be found in many historical buildings around the world. The system is formed by timber joists and brick vaults spanning the distance between two adjacent joists and has an undoubtable aesthetic and cultural value. However, given its geometry, there is no methodology to verify its fire resistance, which has prevented the preservation of many buildings using this system. Within this context, this paper proposes a methodology based on the ¿Reduced cross-section method¿ included in Eurocode 5 (EN 1995-1-2) for the determination of the fire resistance of historical timber jack arch flooring systems subjected to different fire exposures. The methodology is based on the use of the 135-degree and the 300-degree isotherms to obtain the positions of the zero-strength layer and the charring depths, and is supported by both advanced numerical thermal models experimentally validated for standard fire exposure and advanced mechanical models. The methodology has been applied to a wide number of flooring systems covering different span lengths, timber static bending strengths, and fire exposures to evaluate the influence of these parameters on fire resistance. Results show that historical buildings do not always meet the requirements set by current codes and, therefore, performing these analyses is essential to ensure the fire resistance of these timber structures. By doing so, this work also contributes to cultural heritage conservation and to more sustainable construction in alignment with the fulfilment of United Nations 2030 Agenda¿s eleventh goal: "Sustainable cities and communities".The authors wish to express their gratitude to the Spanish Ministry of Economy, Industry and Competitiveness for the funding provided through Project BIA 2014-59036R. This research is also supported by the Spanish Ministry of Science, Innovation and Universities through the PhD grant FPU18/00726 awarded to the first author. Finally, the au-thors want to thank Prof. Dr. Juan Patricio Hidalgo for his help and MSc Enrique Serra for his assistance in the experimental test.Garcia-Castillo, E.; Paya-Zaforteza, I.; Hospitaler Pérez, A. (2021). Analysis of the fire resistance of timber jack arch flooring systems used in historical buildings. Engineering Structures. 243:1-20. https://doi.org/10.1016/j.engstruct.2021.112679S12024

Fire resistance of axially loaded slender concrete filled steel tubular columns. Development of a Three-dimensional numerical model and comparison with eurocode 4

[EN] In recent years, concrete filled tubular (CFT) columns have become popular among designers and structural engineers, due to a series of highly appreciated advantages: high load-bearing capacity, high seismic resistance, attractive appearance, reduced column footing, fast construction technology and high fire resistance without external protection. In a fire, the degradation of the material properties will cause CFT columns to become highly nonlinear and inelastic, which makes it quite difficult to predict their failure. In fact, it is still not possible for analytical methods to predict with enough accuracy the behaviour of columns of this kind when exposed to fire. Numerical models are therefore widely sought. Many numerical simulations have been carried out worldwide, without obtaining satisfactory results. This work proposes a three-dimensional numerical model for studying the actual fire behaviour of columns of this kind. This model was validated by comparing the simulation results with fire resistance tests carried out by other researchers, as well as with the predictions of the Eurocode 4 simplified calculation model.Espinós Capilla, A.; Hospitaler Pérez, A.; Romero, ML. (2009). Fire resistance of axially loaded slender concrete filled steel tubular columns. Development of a Three-dimensional numerical model and comparison with eurocode 4. Acta Polytechnica. 49(1):39-43. http://hdl.handle.net/10251/102170S394349

A new methodology using beam elements for the analysis of steel frames subjected to non-uniform temperatures due to fires

[EN] Non-uniform heating in structures under fire involves the appearance of 3D-phenomena and typically requires the use of complex models built with finite elements shell or solid. Although different procedures have been developed to model the complex thermo-mechanical phenomenon, there is no simple, accurate, and low-cost computational methodology involving the space-time variation of the temperature and displacement fields that opens the path advancing more easily towards modeling more complex structural problems in a fire situation. To overcome this knowledge-gap, this paper presents a new methodology that fulfills those conditions, making it possible to carry out more complex analyses that require many simulations in a short time and at low computational costs. The new methodology to obtain the thermo-mechanical response to non-uniform heating and mechanical loads is general, simple, accurate, and avoids using complex and high-cost finite elements, simplifying the structural modeling, and reducing the computational analysis cost. As a result, complex structural fire engineering problems such as probabilistic and optimization analysis can be handled much more easily, representing a significant step toward the generalized application of performance-based approaches to deal with fire effects on structures. The procedure uses simple but advanced Timoshenko¿s beam-type finite elements and represents the non-uniform temperature space-time field through a mean value of the temperature and the two mean values of the section thermal gradients which are variable in time during the fire. The methodology is satisfactorily validated with results (experimental and numerical) of the Cardington frame test and captures 3D-phenomena such as buckling, flexural-torsional buckling, and warping.Thanks are due to the Fundación Carolina, the Universitat Politècnica de València, and the Universidad Surcolombiana for the support given to this research through the 2018-2019 Ph.D. scholarship.Pallares-Muñoz, MR.; Paya-Zaforteza, I.; Hospitaler Pérez, A. (2021). A new methodology using beam elements for the analysis of steel frames subjected to non-uniform temperatures due to fires. Structures. 31:462-483. https://doi.org/10.1016/j.istruc.2021.02.008S46248331Shan, S., & Li, S. (2020). Fire-induced progressive collapse mechanisms of steel frames with partial infill walls. Structures, 25, 347-359. doi:10.1016/j.istruc.2020.03.023Shakib, H., Zakersalehi, M., Jahangiri, V., & Zamanian, R. (2020). Evaluation of Plasco Building fire-induced progressive collapse. Structures, 28, 205-224. doi:10.1016/j.istruc.2020.08.058Horová, K., Jána, T., & Wald, F. (2013). Temperature heterogeneity during travelling fire on experimental building. Advances in Engineering Software, 62-63, 119-130. doi:10.1016/j.advengsoft.2013.05.001Xu, L., & Zhuang, Y. (2012). Storey-based stability of unbraced steel frames at elevated temperature. Journal of Constructional Steel Research, 78, 79-87. doi:10.1016/j.jcsr.2012.06.010Jacques, L., Béchet, E., & Kerschen, G. (2017). Finite element model reduction for space thermal analysis. Finite Elements in Analysis and Design, 127, 6-15. doi:10.1016/j.finel.2017.01.001B.D. R, M. SK. Behaviour of steel columns with realistic boundary restraints under standard fire. Structures 2020;28:626–37. https://doi.org/https://doi.org/10.1016/j.istruc.2020.08.028.Alos-Moya, J., Paya-Zaforteza, I., Hospitaler, A., & Loma-Ossorio, E. (2019). Valencia bridge fire tests: Validation of simplified and advanced numerical approaches to model bridge fire scenarios. Advances in Engineering Software, 128, 55-68. doi:10.1016/j.advengsoft.2018.11.003Jeffers, A. E., & Beata, P. A. (2014). Generalized shell heat transfer element for modeling the thermal response of non-uniformly heated structures. Finite Elements in Analysis and Design, 83, 58-67. doi:10.1016/j.finel.2014.01.003Rigobello, R., Coda, H. B., & Munaiar Neto, J. (2014). A 3D solid-like frame finite element applied to steel structures under high temperatures. Finite Elements in Analysis and Design, 91, 68-83. doi:10.1016/j.finel.2014.07.005Alos-Moya, J., Paya-Zaforteza, I., Hospitaler, A., & Rinaudo, P. (2017). Valencia bridge fire tests: Experimental study of a composite bridge under fire. Journal of Constructional Steel Research, 138, 538-554. doi:10.1016/j.jcsr.2017.08.008Peris-Sayol, G., Paya-Zaforteza, I., Alos-Moya, J., & Hospitaler, A. (2015). Analysis of the influence of geometric, modeling and environmental parameters on the fire response of steel bridges subjected to realistic fire scenarios. Computers & Structures, 158, 333-345. doi:10.1016/j.compstruc.2015.06.003Quiel, S. E., Moreyra Garlock, M. E., & Paya-Zaforteza, I. (2011). Closed-Form Procedure for Predicting the Capacity and Demand of Steel Beam-Columns under Fire. Journal of Structural Engineering, 137(9), 967-976. doi:10.1061/(asce)st.1943-541x.0000443Davidson, M. T., Harik, I. E., & Davis, D. B. (2013). Fire Impact and Passive Fire Protection of Infrastructure: State of the Art. Journal of Performance of Constructed Facilities, 27(2), 135-143. doi:10.1061/(asce)cf.1943-5509.0000295Allam, A., Nassif, A., & Nadjai, A. (2019). Behaviour of restrained steel beam at elevated temperature – parametric studies. Journal of Structural Fire Engineering, 10(3), 324-339. doi:10.1108/jsfe-11-2018-0036Santiago A, Haremza C, Simões da Silva L, Rodrigues JP. Numerical behaviour of steel columns subject to localized fire loading. In: Topping BH V., Costa Neves LF, Barros RC, editors. Proc. Twelfth Int. Conf. Civil, Struct. Environ. Eng. Comput., Stirlingshire, Scotland: Civil-Comp Press; 2009.Burges I, Alexandrou M. Composite beams. In: Ed. Wald F, Burgess I, Kwasniewski L, Horová K, Caldová E, editors. Benchmark Stud. Verif. Numer. Model. fire Eng. 1st ed., Prague: CTU Publishing House; 2014.Burges I, Alexandrou M. Steel beams. In: Ed. Wald F, Burgess I, Kwasniewski L, Horová K, Caldová E, editors. Benchmark Stud. Verif. Numer. Model. fire Eng. 1st ed., Prague: CTU Publishing House; 2014.Burgess I, Plank R, Shephered P. Vulcan 2019.Santiago A, Haremza C, Lopes F, Franssen JM. Numerical behaviour of steel columns under localized fire loading. In: Ed. Wald F, Burgess I, Kwasniewski L, Horová K, Caldová E, editors. Benchmark Stud. Exp. Valid. Numer. Model. fire Eng. 1st ed., Prague: CTU Publishing House; 2014.Franssen, J. M., Cooke, G. M. E., & Latham, D. J. (1995). Numerical simulation of a full scale fire test on a loaded steel framework. Journal of Constructional Steel Research, 35(3), 377-408. doi:10.1016/0143-974x(95)00010-sSrivastava, G., & Ravi Prakash, P. (2017). An integrated framework for nonlinear analysis of plane frames exposed to fire using the direct stiffness method. Computers & Structures, 190, 173-185. doi:10.1016/j.compstruc.2017.05.013EN 1993-1-2. Eurocode 3: Design of steel structures - Part 1-2: General rules - Structural fire design. Brussels: European Committee for Standardization; 2005.EN 1992-1-2. Eurocode 2: Design of concrete structures - Part 1-2: General rules - Structural fire design. Brussels: European Committee for Standardization; 2004.Purkiss JA, Li LY. Fire safety engineering design of structures. 3rd Editio. Boca Raton: CRC Press; 2013. https://doi.org/10.1201/b16059.Ansys. ANSYS Engineering Analysis System. User manual. Canonsburg, Pensilvania: Houston, Pa. : Swanson Analysis Systems, 2019; 2019.Oñate E. Structural Analysis with the Finite Element Method Linear Statics: Volume 2. Beams, Plates and Shells. 1st ed. Barcelona: Springer; 2013.Magisano, D., Liguori, F., Leonetti, L., de Gregorio, D., Zuccaro, G., & Garcea, G. (2019). A quasi-static nonlinear analysis for assessing the fire resistance of reinforced concrete 3D frames exploiting time-dependent yield surfaces. Computers & Structures, 212, 327-342. doi:10.1016/j.compstruc.2018.11.005Kiakojouri, F., De Biagi, V., Chiaia, B., & Sheidaii, M. R. (2020). Progressive collapse of framed building structures: Current knowledge and future prospects. Engineering Structures, 206, 110061. doi:10.1016/j.engstruct.2019.11006

New modeling strategies for analyzing lateral-torsional buckling in class-4 steel structural members at elevated temperatures using beam-type elements

[EN] Fire is one of the main hazards that can affect steel buildings and bridges and was responsible, e.g., for the collapse of the Plasco building in Tehran, Iran, and the I-65 bridge in Birmingham, Alabama, USA. This vulnerability has motivated the development of advanced computational models to predict the response of steel structures to fire accurately. The mechanical response of slender steel members to fire is especially important because they fail prematurely by buckling at load values below their elastic strength. However, the structural analysis of these members typically requires advanced and complex FE models with shell elements, including initial geometric and material imperfections. These shell models are computationally expensive, complicating the carrying out of parametric and probabilistic studies. Therefore, there is a need to develop simple, accurate, and low-cost computational models as reliable as shell-type models. To overcome this knowledge gap, this paper presents two new modeling strategies that simulate the mechanical response of class-4 steel members subjected to lateral-torsional buckling in fire using Timoshenko beam-type finite elements, which significantly simplify the structural modeling. These strategies are called Fiber Beam Model (FBM) and Cruciform Frame Model (CFM) and include initial geometric and material imperfections and thermal strains. In the FBM, the steel member is represented by a single fiber of I-section beam elements, whereas in the CFM, a cruciform arrangement of rectangular beam finite element fibers idealizes it, making the CFM more complex to build than FBM. Both strategies were satisfactorily validated with experimental and numerical results of Test-1 and Test-3 carried out in the ¿Fire design of steel members with welded or hot-rolled class-4 cross-section¿ (FIDESC4) research project on a slender beam of class-4 section. Although both FBM and CFM correctly captured the LTB resistance of the tested beam, CFM can, in addition, adequately reproduce the local buckling failure and significantly reduced the computational time. That means complex fire engineering problems such as probabilistic and optimization analyses of thin-walled beams can be addressed more easily and accurately, representing an important step towards applying performance-based approaches in slender steel structures under fire.Thanks are due to the Fundacion Carolina for the support given to this research through a Ph.D. scholarship.Pallares-Muñoz, MR.; Paya-Zaforteza, I.; Hospitaler Pérez, A. (2021). New modeling strategies for analyzing lateral-torsional buckling in class-4 steel structural members at elevated temperatures using beam-type elements. Structures. 34:3508-3532. https://doi.org/10.1016/j.istruc.2021.09.087S350835323

Experimental study on the thermal behaviour of fire exposed slim-floor beams

[EN] Steel-concrete composite beams embedded in floors (slim-floors) offer various advantages such as the floor thickness reduction or the ease of installation of under-floor technical equipment. However, this typology presents important differences in terms of thermal behaviour, as compared to other composite beams, when exposed to elevated temperatures. These differences are due to their special configuration, being totally contained within the concrete floor depth. Moreover, the current European fire design code for composite steel-concrete structures (EN 1994-1-2) does not provide any simplified thermal model to evaluate the temperature evolution of each slim-floor part during a fire. Additionally, only a few experimental studies can be found which may help understand the thermal behaviour of these composite beams. This paper presents an experimental investigation on the thermal behaviour of slim-floor beams. Electrical radiative panels were used in the test setup to produce the thermal heating. The thermal gap between the lower flange of the steel profile and the bottom steel plate was studied, being found to be one of the most influential elements over the cross-section temperature gradient. The experimental campaign was developed by varying the cross-section configuration in order to evaluate the influence of this parameter over the slim-floor thermal behavior. Finally, the experiments carried out were used to develop and calibrate a finite element thermal model which may help in further research on the thermal behaviour of slim-floor composite beams.Albero, V.; Espinós, A.; Serra, E.; Romero, ML.; Hospitaler, A. (2018). Experimental study on the thermal behaviour of fire exposed slim-floor beams. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 819-823. https://doi.org/10.4995/ASCCS2018.2018.8288OCS81982

Analysis of concrete-filled steel tubular columns after fire exposure

[EN] Concrete filled steel tubular (CFST) columns have a high probability to resist high temperatures compared to steel structures, whose evaluation after a fire is limited by the resulting deformation. A better understanding of the behaviour of CFST columns after a fire, affected by the maximum temperature achieved by the concrete infill, is required to properly estimate their residual strength and stiffness in order to adopt a reasonable strategy with minimum post-fire repair. In this paper, a fiber beam model for the simulation of the post-fire response of slender concrete-filled steel tubular (CFST) columns is presented. First, the model is validated against experimental results and subsequently it is employed to analyse the post-fire response of circular CFST columns. The variation of the residual strength with the load level for realistic fire resistance times is numerically studied. Actually, in a building, the columns support load even while a fire is being extinguished, so it is important to take into account this loading condition when predicting the post-fire behaviour. Therefore, in this research, the complete analysis comprises three stages: heating, cooling and post-fire under sustained load conditions. The model considers realistic features typical from the fire response of CFST columns, such as the existence of a gap conductance at the steel-concrete interface or the sliding and separation between the steel tube and the concrete.The authors gratefully acknowledge the financial support given by Generalitat Valenciana (Spain) for providing the funding BEST/2017/141 for the first author's stay as a visiting fellow at the School of Engineering of the University of Edinburgh.Ibáñez, C.; Bisby, L.; Rush, D.; Romero, ML.; Hospitaler, A. (2018). Analysis of concrete-filled steel tubular columns after fire exposure. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 795-802. https://doi.org/10.4995/ASCCS2018.2018.7193OCS79580

Valencia bridge fire tests: Experimental study of a composite bridge under fire

[EN] The consequences of bridge fires and the lack of guidelines on the evaluation of the fire resistance of bridges have triggered a lot of recent research. Most of these studies are based on numerical models and thus need validation by experimental studies. This paper aims to bridge this gap by describing a battery of open air fire tests carried out under an experimental bridge at the Universitet Politecnica de Valencia in Valencia, Spain. The bridge, with a 6 m span and a composite deck with two steel I-girders supporting an RC slab, was submitted to four different fire scenarios similar to those of real bridge fires, although smaller in magnitude. Results show that: (a) maximum gas temperatures are reached in the region between the I-girders, (b) as gas and steel temperatures vary significantly along the longitudinal axis of the bridge, it is unrealistic to assume a longitudinally uniform gas or girder temperature (c) temperatures in the bottom flange and the web of the I-girders are very similar and significantly higher than top web temperatures, and (d) the magnitude of the fire load and its position are key factors in the bridge response. This study is of major importance as it enables the validation of the numerical models used in bridge fire engineering and is a crucial step towards the development of a performance-based approach for the design of bridges against fires. The information given will also be useful to those interested in carrying out open air experiinental bridge fire tests. (C) 2017 Elsevier Ltd. All rights reserved.Funding for this research was provided by the Spanish Ministry of Science and Innovation (Research Project BIA 2011-27104). The authors are grateful to the Infrastructure and Safety departments of the Universitat Politecnica de Valencia and the City of Valencia Fire Department (Cuerpo de Bomberos de Valencia), which provided crucial support in conducting the tests. Finally, the authors would like to thank Dr. Luke Bisby from the University of Edinburgh, and Dr. Juan Hidalgo and Dr. Cristian Maluk from the University of Queensland for their advice and support during the early stages of planning the fire tests.Alós-Moya, J.; Paya-Zaforteza, I.; Hospitaler Pérez, A.; Rinaudo, P. (2017). Valencia bridge fire tests: Experimental study of a composite bridge under fire. Journal of Constructional Steel Research. 138:538-554. https://doi.org/10.1016/j.jcsr.2017.08.008S53855413

Recent developments and fire design provisions for CFST columns and slim-floor beams

This paper summarizes the latest technical and scientific progresses on steel-concrete composite structures exposed to fire, presenting the recent research carried out on this subject and the progress of the design codes. In particular, this review focuses on concrete-filled steel tubular columns and slim-floor beams, topics where the authors have carried out extensive research during the last years. The more recent experimental and numerical studies performed by the authors as well as those available in the literature are presented, along with applications where these composite elements have been used in practice. The use of advanced materials, such as high strength steel and concrete, stainless steel, lightweight concrete or geopolymer concrete is considered for the enhancement of the fire behaviour of concrete-filled steel tubular columns and slim-floor beams. Finally, the currently available design methods for the calculation of isolated members at elevated temperatures are reviewed and the recent progress of the code provisions for the fire design of these composite elements is presented