Structural safety in wooden beams under thermal and mechanical loading conditions

The main objective of this paper is to identify different analytical methods which permit the calculation of the stress level in wooden simply supported beams, due to mechanical and thermal loading conditions. Two different wood species, with different cross-sections, will be presented. The fi reresistance, the charring depth layer and the charring rate will be determined using the fi nite element method with Ansys® program. To characterize the stress state in wooden beams, all elements are subjected to mechanical load considering the reduction of the cross-section, infl uenced by thermal action. Another purpose of this work is to identify the ultimate safe load-bearing capacity in wooden beams, subjected to uniform load simultaneously with the thermal effect. All numerical results permit the specifi cation of simple design calculation methods, simplifying the verifi cation of the fi re safety of wooden beams

Modelo computacional para avaliação térmica e mecânica de estruturas em madeira

Este trabalho tem como objectivo avaliar estruturalmente duas espécies de madeira, calculando a sua resistência ao fogo para diferentes cenários de incêndio, através da redução da sua secção. Utilizando o método de elementos finitos, com recurso ao programa de cálculo Ansys®, é desenvolvido um modelo computacional térmico que permite o cálculo da camada e da velocidade de carbonização. O cálculo do perfil de temperaturas para as diferentes secções em estudo, é obtido em regime transiente, considerando as propriedades térmicas não lineares do material, obedecendo ao (EN1995-1-2, 2003). Com base ainda no programa Ansys® é efectuada uma análise numérica estrutural em vigas, solicitadas por uma carga mecânica e sob influência da redução da secção recta, função do efeito térmico, para a determinação dos estados de tensão. A resistência mecânica é obtida, considerando as propriedades mecânicas ortotrópicas da madeira e função da temperatura. Com base em equações analíticas propostas para projecto, é efectuada uma comparação com os resultados numéricos. Outro objectivo é identificar a capacidade de carga última em vigas de madeira, função da imposição de um carregamento mecânico em simultâneo com uma acção térmica, de forma a prever futuras considerações nas opções de projecto. A grande finalidade deste estudo é contribuir com regras práticas de projecto, através da apresentação de gráficos de resistência ao fogo e de uma metodologia de cálculo simplificada, para a determinação do campo de tensões e da capacidade de resistente em vigas de madeira, submetidas a acções térmicas e mecânicas. The main objective of this work is to assess the structural performance of two different timber specimens, calculating the fire resistance due different fire scenarios, through timber cross-section reduction. Using the finite element method, with Ansys® program, a computational model is developed which allows the timber charcoal thickness and the charring rate determination. The temperature evolution, in all studied timber cross-sections, is obtained using a transient thermal analysis, including the non-linear thermal properties, according (EN1995-1-2, 2003). To characterize the stress state in beam components a structural numerical analysis will be conducted with Ansys® program, where all beams are submitted to a mechanical load and with the cross-section reduction influence due thermal effect. The mechanical strength is obtained, considering the orthotropic mechanical properties of wood material, dependent of the temperature. Based on proposed analytical design equations, a comparison with numerical results will be obtained. Another objective of this work is to identify the ultimate load capacity in wooden beams, function of mechanical loading condition in simultaneous with thermal effect, in prevention to future design options. The greater purpose of this study is to contribute with design practical rules, through fire resistance charts and a simplified calculation methodology, for stresses and ultimate load capacity calculation in wooden beams submitted to thermal and mechanical loading conditions

Aplicación de la metodología MESMIS para la evaluación de sostenibilidad de los sistemas de producción familiares en el bioma Pampa: Análisis inicial

publishedTomo I . Sección: Sistemas Ganaderos-Economía y Gestión. Sesión: Sostenibilidad. Ponencia nº 3

Avaliação estrutural de duas espécies de madeira submetidas à acção do fogo

Um dos objectivos deste trabalho é avaliar estruturalmente duas espécies de madeira, calculando a sua resistência ao fogo para diferentes cenários de incêndio e determinando a redução da sua secção recta. Será utilizado o método dos elementos finitos através do programa ANSYS para a determinação da camada e da velocidade de carbonização, nas diferentes análises em estudo. O cálculo do perfil de temperaturas, nas diferentes secções em estudo, será obtido em regime transiente. Serão consideradas as propriedades térmicas não lineares do material, dependentes da evolução da temperatura, de acordo com as regras estabelecidas no [Eurocódigo 5, 2003]. O outro objectivo deste trabalho é a determinação de estados de tensão em elementos do tipo viga, sob influência da redução da secção recta. Neste tipo de estudo, será dada particular importância às propriedades ortotrópicas da madeira, função da temperatura, a utilizar no modelo de elementos finitos. Este trabalho será organizado de forma a contribuir com regras práticas de projecto, na utilização deste tipo de elementos estruturais, através da apresentação de gráficos da resistência ao fogo e de uma metodologia de cálculo simplificada, na determinação do campo de tensões em vigas submetidas a acções térmicas e mecânicas

Isothermal Variation Of The Entropy (Δ St) For The Compound Gd5 Ge4 Under Hydrostatic Pressure

In the present work, the isothermal variation of the entropy (Δ ST) for the compound Gd5 Ge4 was studied at different applied hydrostatic pressures (from 0 up to 0.58 GPa). In all pressure ranges, we observe the giant magnetocaloric effect. The Δ ST data for the compound Gd5 Ge4 at zero applied pressure present two peaks: the lowest temperature peak is due to irreversible processes and the highest temperature peak is due to magnetostructural transitions. Increasing the pressure, the lowest temperature peak displaces to lower temperatures and disappears. The magnitude of the other peak has a nonlinear behavior with pressure. Different protocols were used to obtain Δ ST at zero applied pressure and the results indicate that Δ ST strongly depends on the initial and final states of Gd5 Ge4 compound. We also present a T-P magnetic phase diagram built from the available magnetic data. © 2008 American Institute of Physics.1046Pecharsky, V.K., Gschneidner Jr., K.A., (1999) J. Magn. Magn. Mater., 200, p. 44. , 0304-8853 10.1016/S0304-8853(99)00397-2Tishin, A.M., Spichkin, Y.I., (2003) The Magnetocaloric Effect and Its Applications, , (IOP, Bristol)Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Phys. Rev. Lett., 78, p. 4494. , 0031-9007 10.1103/PhysRevLett.78.4494Magen, C., Arnold, Z., Morellon, L., Skorokhod, Y., Algarabel, P.A., Ibarra, M.R., Kamarad, J., (2003) Phys. Rev. Lett., 91, p. 207202. , 0031-9007 10.1103/PhysRevLett.91.207202Levin, E.M., Gschneidner Jr., K.A., Pecharsky, V.K., (2002) Phys. Rev. B, 65, p. 214427. , 0163-1829 10.1103/PhysRevB.65.214427Levin, E.M., Pecharsky, V.K., Gschneidner Jr., K.A., Miller, G.J., (2001) Phys. Rev. B, 64, p. 235103. , 0163-1829 10.1103/PhysRevB.64.235103Tang, H., Pecharsky, V.K., Gschneidner Jr., K.A., (2004) Phys. Rev. B, 69, p. 064410. , 0163-1829 10.1103/PhysRevB.69.064410Chattopadhyay, M.K., Manekar, M.A., Pecharsky, A.O., Pecharsky, V.K., Gschneidner Jr., K.A., Moore, J., Perkins, G.K., Cohen, L.F., (2004) Phys. Rev. B, 70, p. 214421. , 0163-1829 10.1103/PhysRevB.70.214421Mudryk, Ya., Holm, A.P., Gschneidner Jr., K.A., Pecharsky, V.K., (2005) Phys. Rev. B, 72, p. 064442. , 0163-1829 10.1103/PhysRevB.72.064442Levin, E.M., Gschneidner Jr., K.A., Lograsso, T.A., Schlagel, D.L., Pecharsky, V.K., (2004) Phys. Rev. B, 69, p. 144428. , 0163-1829 10.1103/PhysRevB.69.144428Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Appl. Phys. Lett., 70, p. 3299. , 0003-6951 10.1063/1.119206Nikitin, S.A., Myalikgulyev, G., Tishin, A.M., Annaorazov, M.P., Asatryan, K.A., Tyurin, A.L., (1990) Phys. Lett. A, 148, p. 363. , 0375-9601 10.1016/0375-9601(90)90819-APecharsky, V.K., Gschneidner Jr., K.A., (1999) J. Appl. Phys., 86, p. 565. , 0021-8979 10.1063/1.370767Carvalho, A.M.G., (2006), Ph.D. thesis, UNICAMPCarvalho, A.M.G., Alves, C.S., De Campos, A., Coelho, A.A., Gama, S., Gandra, F.C.G., Von Ranke, P.J., De Oliveira, N.A., (2005) J. Appl. Phys., 97, pp. 10M320. , 0021-8979 10.1063/1.1860932Gschneidner Jr., K.A., Pecharsky, V.K., (2000) Annu. Rev. Mater. Sci., 30, p. 387. , 0084-6600 10.1146/annurev.matsci.30.1.387Carvalho, A.M.G., Alves, C.S., Colucci, C.C., Bolanho, M.A., Coelho, A.A., Gama, S., Nascimento, F.C., Cardoso, L.P., (2007) J. Alloys Compd., 432, p. 11. , 0925-8388 10.1016/j.jallcom.2006.05.121Wood, M.E., Potter, W.H., (1985) Cryogenics, 25, p. 667. , 0011-2275 10.1016/0011-2275(85)90187-0Magnus, A., Carvalho, G., Coelho, A.A., Gama, S., Von Ranke, P.J., De Oliveira, N.A., Da Silva, L.M., Gandra, F.C.G., (submitted

Studies toward the synthesis of Amaryllidaceae alkaloids from Morita-Baylis-Hillman adducts: a straightforward synthesis of functionalized dihydroisoquinolin-5(6H)-one core

We disclose herein our results concerning a study aiming at the synthesis of the highly substituted carbon skeleton of alkaloids isolated from plants of the Amaryllidaceae family. The total synthesis of the functionalized dihydroisoquinolin-5(6H)-one core, which is the bottom part of the structure of alkaloids isolated from this botanic family, is described, using Morita-Baylis-Hillman adducts as substrate. This compound should be a useful and valuable intermediate for the total synthesis of alkaloids isolated from Amaryllidaceae

Differences between FEV6, FVC and VC at the diagnosis of obstructive ventilatory defect

Introduction: The diagnosis of airway obstruction can be made through FEV1/FVC ratio <0.7 or FEV1/VC ratio < lower limit of normality (LLN). Several authors advocate that FEV1/FEV6 ratio is an alternative to diagnosing obstructive ventilatory defect, while others have determined that the best cut-off for this ratio (best combined sensitivity and specificity) is 0.73. Objective: To evaluate the non-inferiority of FEV1/FEV6 ratio < 0.73 when compared to FEV1/ FVC ratio < 0.7 and FEV1/VC < LLN in diagnosing airway obstruction. Methods: A retrospective analysis of the medical records from patients who underwent spirometry or plethysmography in a university central hospital from June 1st to December 31st, 2018 was carried out. Only medical records which included FEV1/FVC < 0.7 or FEV1/VC < LLN were selected, and these results were compared to FEV1/FEV6 ratio. Results: A total of 526 patients with obstructive ventilatory defect were identified by one of the two ratios described. Of these, 95.1%, 87.4% and 88.6% were obstructive by FEV1/FVC, FEV1/ VC, and FEV1/FEV6 ratio, respectively. The positive predictive value (PPV) of FEV1/FEV6 in relation to FEV1/FVC ratio was 99.6% (p < 0.001) with a diagnostic efficacy of 92.8%, whereas the PPV of FEV1/FEV6 in relation to FEV1/VC was 91.0% (p 70% (mild obstruction) and in individuals aged >50 years. Conclusions: FEV1/FEV6 < 0.73 may be a good alternative ratio, as it is non-inferior to FEV1/VC and FEV1/FVC in diagnosing obstructive ventilatory defect.info:eu-repo/semantics/publishedVersio

Performance Assessment of UWB-Over-Fiber and Applications

Organic chemistr

Seropositivity of Coxiella burnetii in wild boar (Sus scrofa) and red deer (Cervus elaphus) in Portugal

Coxiella burnetii is a zoonotic microorganism that infects a wide range of wild and domestic species, causing the disease Q fever, frequently involving ticks as vectors. To better understand the occurrence of C. burnetii infection in wild boar (Sus scrofa) and red deer (Cervus elaphus), an epidemiological study was conducted in the Centre region of Portugal.info:eu-repo/semantics/publishedVersio

Hybrid wood/steel elements under fire

The main objective of this paper is to present a computational model for the fire resistance of wood/steel hybrid elements. Different design solutions will be presented. The most important factors for fire safety in hybrid elements are the thermal effects degradation and the charring depth formation in wood materials, and also the heat conduction extremely well in steel material. Unprotected steel elements under fire condition may suffer serious damage. The use of hybrid wood/steel elements could increase both structural strength and stiffness. Wood could be considered as an insulating material, the core section could remain at low temperature, function of fire exposure time and element cross section size. All presented results will permit to evaluate different design solutions, which facilitates the fire design of wood/steel hybrid elements. The presented study was conducted in order to articulate the best constructive solution using the finite element method