Model-based analysis of a concrete building subjected to fire

Draft paper: to be presented at Advanced Research Workshop on Fire Computer Modelling, Santander, Spain, 19 October 2007A case study is presented of the Windsor Tower fire in Madrid, a mainly concrete-framed office block, which was involved in a major, multiple floor fire in February 2005. The performance of the structure is documented and examined using all available methods, including analysis of data on the fire and computer modelling of the fire and structure. Holistic structural performance during a fire is more complex than the effects of fire upon individual members which make up the structure. In concrete structures, fire conditions can have a variety of structural effects, both positive and negative, beyond the deterioration of the mechanical properties of the material. In order to properly understand the performance of concrete buildings, comprehensive models, which account for all relevant factors, are required. One of the key challenges is the limited data available from well-instrumented full-scale tests on whole concrete structures, compared to the large amount of data on the behaviour of individual concrete members and the large number of experiments carried out on steel and composite steel/concrete structures. Here, a systematic approach is adopted for modelling, building up from fundamental, but simplified, analyses. The fire conditions have been computed using simplified analyses and Computational Fluid Dynamic (CFD) modelling. Similarly, the thermal and mechanical response of the structure is assessed using simplified analyses and Finite Element Method (FEM) modelling. The CFD simulations provide the fire exposure histories of the structural members. The FEM calculations have examined the structural effects of changes to the concrete properties due to increased temperature. Extrapolation of results can examine redundancies within a building and their mobilisation to prevent collapse of the structure in the case of fire. The paper gives an introduction to the Windsor Tower structure, the fire itself and further details of the methods used in modelling the fire and structural response. Model sizing, structural properties and failure modes are discussed along with initial analysis

Analysis of thermal fields generated by natural fires on the structural elements of tall buildings

The Windsor Tower in Madrid was involved in a major fire, on 12-13 February 2005, which caused extensive structural damage to the upper floors of the building. This fire has provoked intense interest amongst researchers hoping to better understand the performance of concrete structures in fire. A research team integrated for Group GIDAI (University of Cantabria –Spain) and BRE Centre for Fire Safety Engineering (The Edinburgh University – UK) has begun a study with the purpose of properly characterising the fire and the performance of the structure. The objectives of the study are (1) to analyze the fire growth conditions in order to understand the fire propagation mechanisms between floors of the building, using computational fire modelling, and (2) to evaluate the response of the structure to the fire. The research undertaken on the fire propagation on the 21st floor, the origin of the fire, has allowed assessment of the severity conditions reached as consequence of the fully-developed fire, due the combustion of the present flammable materials. Starting from these results, characteristic curves of heat release rate representative of the real fire have been determined, to facilitate study of the thermal attack (temperatures, heat flux, etc.) on the structural elements. The tools used for this purpose were the Fire Dynamics Simulator (FDS) LES code, developed at the National Institute of Standards and Technology (NIST), and the SOFIE RANS code. These results will allow, in the next stages, to make use of finite element methods to obtain the corresponding thermal and mechanical state (stress and strain) of each element due to these conditions

Modelling of the thermal solicitations of concrete structural elements in tall buildings under natural fires

RESUMEN. El incendio de la Torre Windsor de Madrid constituye un suceso paradigmático de incendios en edificios de gran altura. En el presente Estudio se analizan las condiciones de origen, desarrollo y propagación de incendios reales en este tipo de edificaciones, así como la determinación de las condiciones de exposición (temperaturas T , flujos de calor q′′, etc.) a las que se encuentran sometidos los elementos estructurales, en condiciones de uso final en este tipo de estructuras, mediante la utilización de técnicas de modelado y simulación computacional de incendios. Los trabajos realizados, se centraron en aquellas actuaciones que: 1) permitieran validar la capacidad predictiva de los modelos de fluido-dinámica empleados, 2) la aplicación de los modelos ajustados y validados a un escenario de incendio en condiciones de uso final en un edificio de gran altura, para la predicción de la respuesta mecánica de la trama estructural.ABSTRACT. The fire of the Windsor Building in Madrid represents a paradigm in High Rise Building Fires. The present Work analyzes the origin, growth and propagation conditions of natural fires in tall buildings. The Study has been focused on the determination of the thermal exposure conditions (temperatures T, heat fluxes q′′, etc.) on the structural members of high rise buildings, at end use conditions, under natural fires using fire computer modeling techniques. Work allowed: 1) validate the predictive capacity of the fluid-dynamics computer models used, 2) apply these models to a specific fire scenario to assess the thermal and the mechanical response of the structural members of a high rise building

Trasplante de células hematopoyéticas

El trasplante de células hematopoyéticas (TCH) es la infusión de células progenitoras a fin de restablecer la función medular e inmune en pacientes con enfermedades hematológicas malignas y no malignas adquiridas y genéticas. El impacto del TCH se refleja en las alternativas de tratamiento, mayor difusión de la técnica y mejores opciones al paciente.El procedimiento consiste en la obtención de progenitores hematopoyéticos periféricos, mediante las células CD34+ (2- 2.5 x 106/Kg peso); es un excelente predictor de prendimiento del injerto. El trasplante de donante no relacionado, permite tratamiento a pacientes que carecen de donantes familiares histo-idénticos. Otra variante de TCH es el mini-trasplante, utilizando dosis bajas de quimioterapia e inmunosupresores, produciendo menos complicaciones, pero jerarquizando el efecto “injerto sobre tumor”, que permite la remisión de enfermedades neoplásicas hematológicas y no hematológicas, siendo una alternativa en países en vías de desarrollo, por la posibilidad de disminuir costos y complicaciones

A Priori Modelling of Fire Test One

Chapter 10 in the book: The Dalmarnock Fire Tests: Experiments and Modelling, Edited by G. Rein, C. Abecassis Empis and R. Carvel, Published by the School of Engineering and Electronics, University of Edinburgh, 2007. ISBN 978-0-9557497-0-4An international round-robin study of fire modelling was conducted prior to the Dalmarnock Fire Tests in order to assess the state-of-the-art of fire modelling in real scenarios. The philosophy behind the Dalmarnock Fire Tests was to provide instrumentation density suitable for comparison to field models and designed the scenario for maximum test reproducibility. Each participating team independently simulated a priori the test using a common detailed description of the compartment geometry, fuel packages, ignition source and ventilation conditions. The aim of the exercise was to forecast the test results as accurately as possible, and not to provide an engineering analysis with adequate conservative assumptions or safety factors. The modelling results and experimental measurements are compared among themselves, allowing for conclusions on the robustness, reliability and accuracy of current modelling practices. The results indicate large scatter and considerable disparity among predicted fires and also differing from the experimental data. The Dalmarnock Fire Test One was benchmarked against a second test to establish the potential experimental variability. The scatter of the simulations is much larger than the experimental error and the experimental variability. The study emphasises on the inherent difficulty of predicting fire dynamics and demonstrates that the main source of scatter is originated in the many degrees of freedom and the uncertainty in the input parameters. The conclusions from the study are made public to encourage debate and exchange of views on the topic of fire modelling

Round-robin study of a priori modelling predictions of the Dalmarnock Fire Test One

Peer-reviewed journal paper published in 2009 about the international modelling exercise conducted in 2006.An international study of fire modelling was conducted prior to the Dalmarnock Fire Test One in order to assess the state-of-the-art of fire simulations using a round-robin approach. This test forms part of the Dalmarnock Fire Tests, a series of experiments conducted in 2006 in a high-rise building. The philosophy behind the tests was to provide measurements in a realistic fire scenario involving multiple fuel packages and non-trivial fire growth, and with an instrumentation density suitable for comparison with computational fluid dynamics models. Each of the seven round-robin teams independently simulated the test scenario a priori using a common detailed description of the compartment geometry, fuel packages, ignition source and ventilation conditions. The aim of the exercise was to forecast the fire development as accurately as possible and compare the results. The aim was not to provide an engineering analysis with conservative assumptions or safety factors. Comparison of the modelling results shows a large scatter and considerable disparity among the predictions, and between predictions and experimental measurements. The scatter of the simulations is much larger than the error and variability expected in the experiments. The study emphasises on the inherent difficulty of modelling fire dynamics in complex fire scenarios like Dalmarnock, and shows that the accuracy to predict fire growth (i.e. evolution of the heat released rate) is, in general, poor

Antimicrobial and Antibiofilm Activity against Streptococcus mutans of Individual and Mixtures of the Main Polyphenolic Compounds Found in Chilean Propolis

Dental caries is multifactorial disease and an important health problem worldwide. Streptococcus mutans is considered as a major cariogenic agent in oral cavity. This bacteria can synthetize soluble and insoluble glucans from sucrose by glucosyltransferases enzymes and generate stable biofilm on the tooth surface. Biological properties of Chilean propolis have been described and it includes antimicrobial, antifungal, and antibiofilm activities. The main goal of this study was to quantify the concentrations of main flavonoids presents in Chilean propolis and compare some biological properties such as antimicrobial and antibiofilm activity of individual compounds and the mixture of this compounds, against S. mutans cultures. Chilean propolis was studied and some polyphenols present in this extract were quantified by HPLC-DAD using commercial standards of apigenin, quercetin, pinocembrin, and caffeic acid phenethyl ester (CAPE). MIC for antimicrobial activity was determined by serial dilution method and biofilm thickness on S. mutans was quantified by confocal microscopy. Pinocembrin, apigenin, quercetin, and caffeic acid phenethyl ester (CAPE) are the most abundant compounds in Chilean propolis. These polyphenols have strong antimicrobial and antibiofilm potential at low concentrations. However, pinocembrin and apigenin have a greater contribution to this action. The effect of polyphenols on S. mutans is produced by a combination of mechanisms to decrease bacterial growth and affect biofilm proliferation due to changes in their architecture

Fetal alcohol syndrome and fetal alcohol effects among children in a secondary nutritional recovery centre Sindrome de alcoholismo fetal y efectos del alcohol sobre el feto: Importancia del diagnóstico precoz y del manejo nutricional

Background: Fetal alcohol syndrome (FAS) and fetal alcohol effects (FAE) encompass a pattern of birth defects in persons whose mothers ingested alcohol during pregnancy. People with FAE display fewer of the FAS traits. Aim: To assess the prevalence and features of these affections in a secondary nutritional recovery centre. Patients and methods: All charts of children admitted between 1985 and 1995 were reviewed, and those children diagnosed as having a FAS or FAE by a geneticist were considered for this study. Birth, maternal, social and economic characteristics, psychomotor abilities (using Denver test) and response to nutritional treatment were assessed. Results: During the study period, 1572 infants were admitted to the centre, and 1.97% (70% female) were diagnosed as having a FAS or FAE. These infants were admitted at 11.1 ± 4.5 months of age and discharged after 96.7 ± 58.1 months of hospitalisation. Mean mother's age was 33 ± 7 years, and all belonged to low socioeconomic level