Fire behaviour of concrete filled elliptical steel columns

In this work, a non-linear three-dimensional finite element model is presented in order to study the behaviour of axially loaded concrete filled elliptical hollow section (CFEHS) columns exposed to fire. This study builds on previous work carried out by the authors on concrete filled circular hollow section (CFCHS) columns both at room temperature and in fire. The numerical model is first validated at room temperature against a series of experiments on CFEHS stub columns available in the literature and subsequently extended to study the performance of slender columns at elevated temperatures. The aim of this work is to understand and represent the behaviour of axially loaded CFEHS columns in fire situations and to compare their effectiveness with that of the circular concrete filled tubular (CFT) columns. Parametric studies to explore the influence of variation in global member slenderness, load level, cross-section slenderness and section size are presented. Finally, guidance on the fire design of CFEHS columns is proposed: it is recommended to follow the guidelines of Clause 4.3.5.1 in EN 1994-1-2, but employing the flexural stiffness reduction coefficients established in the French National Annex with an equivalent EHS diameter equal to P/¿, where P is the perimeter of the ellipse.The authors would also like to acknowledge Universidad Politecnica de Valencia for providing fellowship funding for the first author's stay as a visiting academic at Imperial College London.Espinós Capilla, A.; Gardner, L.; Romero, ML.; Hospitaler Pérez, A. (2011). Fire behaviour of concrete filled elliptical steel columns. Thin-Walled Structures. 49(2):239-255. https://doi.org/10.1016/j.tws.2010.10.008S23925549

Portfolio of Bio-Based Façade Materials

This chapter presents a selection of biomaterials identified by industry and academia as superior for building façades. Time series of photographs demonstrating changes of material appearance during use phase are provided for each case. In addition, selected technical characteristic, durability, recyclability potential as well as costing estimates are provided for each biomaterial

Fire design method for concrete filled tubular columns based on equivalent concrete core cross-section

In this work, a method for a realistic cross-sectional temperature prediction and a simplified fire design method for circular concrete filled tubular columns under axial load are presented. The generalized lack of simple proposals for computing the cross-sectional temperature field of CFT columns when their fire resistance is evaluated is evident. Even Eurocode 4 Part 1-2, which provides one of the most used fire design methods for composite columns, does not give any indications to the designers for computing the cross-sectional temperatures. Given the clear necessity of having an available method for that purpose, in this paper a set of equations for computing the temperature distribution of circular CFT columns filled with normal strength concrete is provided. First, a finite differences thermal model is presented and satisfactorily validated against experimental results for any type of concrete infill. This model consideres the gap at steel-concrete interface, the moisture content in concrete and the temperature dependent properties of both materials. Using this model, a thermal parametric analysis is executed and from the corresponding statistical analysis of the data generated, the practical expressions are derived. The second part of the paper deals with the development of a fire design method for axially loaded CFT columns based on the general rules stablished in EN 1994-1-1 and employing the concept of room temperature equivalent concrete core cross-section. In order to propose simple equations, a multiple nonlinear regression analysis is made with the numerical results generated through a thermo-mechanical parametric analysis. Once more, predicted results are compared to experimental values giving a reasonable accuracy and slightly safe results.The authors would like to express their sincere gratitude to the Spanish Ministry of Economy and Competitivity for the help provided through the project BIA2012-33144, and to the European Community for the FEDER funds.Ibáñez Usach, C.; Aguado, JV.; Romero, ML.; Espinós Capilla, A.; Hospitaler Pérez, A. (2015). Fire design method for concrete filled tubular columns based on equivalent concrete core cross-section. Fire Safety Journal. 78:10-23. https://doi.org/10.1016/j.firesaf.2015.07.009S10237

Assessment of biochar and hydrochar as minor to major constituents of growing media for containerized tomato production

"This is the peer reviewed version of the following article: Fornes, Fernando, Rosa M Belda, Pascual Fernández de Córdova, and Jaime Cebolla-Cornejo. 2017. Assessment of Biochar and Hydrochar as Minor to Major Constituents of Growing Media for Containerized Tomato Production. Journal of the Science of Food and Agriculture 97 (11). Wiley: 3675 84. doi:10.1002/jsfa.8227, which has been published in final form at https://doi.org/10.1002/jsfa.8227. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."[EN] BACKGROUND: Chars are emerging materials as constituents of growth media. However, chars of different origin differ in their characteristics and more studies are needed to ratify them for such a role. The characteristics of coir mixed with 0%, 10%, 25%, 50%, 75%, and 100% (v/v) of two biochars, from forest waste (BCH-FW) and from olive mill waste (BCH-OMW), and one hydrochar, from forest waste (HYD-FW), and their effects on growth, yield and fruit quality of two tomato cultivars (Gransol RZ and Cuarenteno) were assessed. RESULTS: Chars negatively affected plant growth and yield but not fruit quality. The effect was related to the char dose and was larger in HYD-FW and BCH-FW than in BCH-OMW, despite the high salinity of the latter, and more acute in Cuarenteno than in Gransol RZ. The results were discussed on the basis of the large particle size of BCH-FW, which could have caused low nutrient solution retention and, hence, reduced plant nutrient uptake, and the highwater-holding capacity, poor aeration and large CO2 emission of HYD-FW, which could lead to root anoxia. CONCLUSION: BCH-OMW can be used at high proportion in media for tomato cultivation. The use of BCH-FW at a high proportion might be taken into consideration after adjusting particle size, yet this needs additional assays. HYD-FW is inadequate for soilless containerized tomato cultivation. (C) 2017 Society of Chemical IndustryThis study was funded by the Universitat Politecnica de Valencia (Proyectos de nuevas Lineas de Investigacion Multidisciplinares; PAID-05-12).Fornes Sebastiá, F.; Belda Navarro, RM.; Fernández De Córdova Martínez, PJ.; Cebolla Cornejo, J. (2017). Assessment of biochar and hydrochar as minor to major constituents of growing media for containerized tomato production. Journal of the Science of Food and Agriculture. 97(11):3675-3684. https://doi.org/10.1002/jsfa.8227S367536849711Martí, R., Roselló, S., & Cebolla-Cornejo, J. (2016). Tomato as a Source of Carotenoids and Polyphenols Targeted to Cancer Prevention. Cancers, 8(6), 58. doi:10.3390/cancers8060058Dorais, M., Ehret, D. L., & Papadopoulos, A. P. (2008). Tomato (Solanum lycopersicum) health components: from the seed to the consumer. Phytochemistry Reviews, 7(2), 231-250. doi:10.1007/s11101-007-9085-xSchmilewski, G. (2009). GROWING MEDIUM CONSTITUENTS USED IN THE EU. Acta Horticulturae, (819), 33-46. doi:10.17660/actahortic.2009.819.3Graber, E. R., Meller Harel, Y., Kolton, M., Cytryn, E., Silber, A., Rav David, D., … Elad, Y. (2010). Biochar impact on development and productivity of pepper and tomato grown in fertigated soilless media. Plant and Soil, 337(1-2), 481-496. doi:10.1007/s11104-010-0544-6Dumroese, R. K., Heiskanen, J., Englund, K., & Tervahauta, A. (2011). Pelleted biochar: Chemical and physical properties show potential use as a substrate in container nurseries. Biomass and Bioenergy, 35(5), 2018-2027. doi:10.1016/j.biombioe.2011.01.053Vaughn, S. F., Kenar, J. A., Thompson, A. R., & Peterson, S. C. (2013). Comparison of biochars derived from wood pellets and pelletized wheat straw as replacements for peat in potting substrates. Industrial Crops and Products, 51, 437-443. doi:10.1016/j.indcrop.2013.10.010Steiner, C., & Harttung, T. (2014). Biochar as a growing media additive and peat substitute. Solid Earth, 5(2), 995-999. doi:10.5194/se-5-995-2014Petruccelli, R., Bonetti, A., Traversi, M. L., Faraloni, C., Valagussa, M., & Pozzi, A. (2015). Influence of biochar application on nutritional quality of tomato (Lycopersicon esculentum). Crop and Pasture Science, 66(7), 747. doi:10.1071/cp14247Libra, J. A., Ro, K. S., Kammann, C., Funke, A., Berge, N. D., Neubauer, Y., … Emmerich, K.-H. (2011). Hydrothermal carbonization of biomass residuals: a comparative review of the chemistry, processes and applications of wet and dry pyrolysis. Biofuels, 2(1), 71-106. doi:10.4155/bfs.10.81Fornes, F., Belda, R. M., & Lidón, A. (2015). Analysis of two biochars and one hydrochar from different feedstock: focus set on environmental, nutritional and horticultural considerations. Journal of Cleaner Production, 86, 40-48. doi:10.1016/j.jclepro.2014.08.057Kuzyakov, Y., Subbotina, I., Chen, H., Bogomolova, I., & Xu, X. (2009). Black carbon decomposition and incorporation into soil microbial biomass estimated by 14C labeling. Soil Biology and Biochemistry, 41(2), 210-219. doi:10.1016/j.soilbio.2008.10.016Bargmann, I., Martens, R., Rillig, M. C., Kruse, A., & Kücke, M. (2013). Hydrochar amendment promotes microbial immobilization of mineral nitrogen. Journal of Plant Nutrition and Soil Science, 177(1), 59-67. doi:10.1002/jpln.201300154Bargmann, I., Rillig, M. C., Buss, W., Kruse, A., & Kuecke, M. (2013). Hydrochar and Biochar Effects on Germination of Spring Barley. Journal of Agronomy and Crop Science, 199(5), 360-373. doi:10.1111/jac.12024Akhtar, S. S., Li, G., Andersen, M. N., & Liu, F. (2014). Biochar enhances yield and quality of tomato under reduced irrigation. Agricultural Water Management, 138, 37-44. doi:10.1016/j.agwat.2014.02.016Vaccari, F. ., Maienza, A., Miglietta, F., Baronti, S., Di Lonardo, S., Giagnoni, L., … Genesio, L. (2015). Biochar stimulates plant growth but not fruit yield of processing tomato in a fertile soil. Agriculture, Ecosystems & Environment, 207, 163-170. doi:10.1016/j.agee.2015.04.015Cortés-Olmos, C., Valcárcel, J. V., Roselló, J., Díez, M. J., & Cebolla-Cornejo, J. (2015). Traditional Eastern Spanish varieties of tomato. Scientia Agricola, 72(5), 420-431. doi:10.1590/0103-9016-2014-0322Fornes, F., Belda, R. M., Carrión, C., Noguera, V., García-Agustín, P., & Abad, M. (2007). Pre-conditioning ornamental plants to drought by means of saline water irrigation as related to salinity tolerance. Scientia Horticulturae, 113(1), 52-59. doi:10.1016/j.scienta.2007.01.008Cebolla-Cornejo, J., Valcárcel, M., Herrero-Martínez, J. M., Roselló, S., & Nuez, F. (2012). High efficiency joint CZE determination of sugars and acids in vegetables and fruits. ELECTROPHORESIS, 33(15), 2416-2423. doi:10.1002/elps.201100640Cebolla-Cornejo, J., Roselló, S., Valcárcel, M., Serrano, E., Beltrán, J., & Nuez, F. (2011). Evaluation of Genotype and Environment Effects on Taste and Aroma Flavor Components of Spanish Fresh Tomato Varieties. Journal of Agricultural and Food Chemistry, 59(6), 2440-2450. doi:10.1021/jf1045427Dunlop, S. J., Arbestain, M. C., Bishop, P. A., & Wargent, J. J. (2015). Closing the Loop: Use of Biochar Produced from Tomato Crop Green waste as a Substrate for Soilless, Hydroponic Tomato Production. HortScience, 50(10), 1572-1581. doi:10.21273/hortsci.50.10.1572Bunt, A. C. (1988). Media and Mixes for Container-Grown Plants. doi:10.1007/978-94-011-7904-1Mukherjee, A., & Zimmerman, A. R. (2013). Organic carbon and nutrient release from a range of laboratory-produced biochars and biochar–soil mixtures. Geoderma, 193-194, 122-130. doi:10.1016/j.geoderma.2012.10.002Schulz, H., & Glaser, B. (2012). Effects of biochar compared to organic and inorganic fertilizers on soil quality and plant growth in a greenhouse experiment. Journal of Plant Nutrition and Soil Science, 175(3), 410-422. doi:10.1002/jpln.201100143Fornes, F., Carrión, C., García-de-la-Fuente, R., Puchades, R., & Abad, M. (2010). Leaching composted lignocellulosic wastes to prepare container media: Feasibility and environmental concerns. Journal of Environmental Management, 91(8), 1747-1755. doi:10.1016/j.jenvman.2010.03.01

Quantum Interference Effects in Molecular Y- and Rhomb-Type Systems

In this paper we report the first observation of molecular population trapping in four level systems. Constructive and destructive quantum interferences between two sum-frequncy two-photon transitions in Y- and rhomb-type four-level systems, respectively, im sodium molecules have been experimentally achieved by using only one laser source. Their energy level schemes are featured by the extremely near-resonant enhancement of the equal-frequency two-photon transitions, sharing both the initial and the intermediate levels for the Y-type, and sharing both the initial and the final levels for the rhomb-type systems. Their novel spectral effects are to show seriously restrained Doppler-free UV peak at the nominal location of the induced two-photon transition with visible fluorescence in rhomb-type schems, and to show a strong extra UV peak but null visible fluorescence in the middle between the two dipole allowed two-photon transitions

Feasibility of the quantification of respirable crystalline silica by mass on aerosol sampling filters using Raman microscopy

Airborne respirable crystalline silica (RCS) is a hazard that can affect the health of workers and more sensitive measurements are needed for the assessment of worker exposure. To investigate the use of Raman microscopy for the analysis of RCS particulate collected on filters, aliquots of quartz or cristobalite suspended in isopropanol were pipetted onto silver filters. Samples were measured by arbitrarily selecting positions along the filter and collecting spectra at 50 discrete points. The calculated limits of quantification on test samples were between ~0.066 – 0.161 µg and 0.106 – 0.218 µg for quartz and cristobalite respectively. Three respirable quartz calibration dusts (A9950, NIST 1878 and Quin B) with different mass median aerodynamic particle sizes obtained similar Raman response relationships per unit mass. The difference between NIST 1878 and Quin B was not significant (p=0.22). The intermediate measurement precision of replicate samples was 10 - 25% over the measured range for quartz (0.25 – 10 µg) and could potentially be improved. Results from mixtures of quartz and cristobalite were within 10 % of their theoretical values. Results from samples of 5 % quartz in calcite were close to the theoretical quartz mass. The upper measurement limit for a mixture of 20 % RCS in the light absorbing mineral hematite (Fe2O3) was 5 µg. These data show that Raman spectroscopy is a viable option for the quantification of the mass of respirable crystalline silica on filters with a limit of detection approaching 1/10th of that obtained with other techniques. The improvement in sensitivity may enable the measurement of particulate in samples from low concentration environments (e.g. inside a mask) or from miniature samplers operating at low flow rates

Effect of Fe:ligand ratios on hydroponic conditions and calcareous soil in Solanum lycopersicum L. and Glycine max L. fertilized with heptagluconate and gluconate

BACKGROUND: The environmental risk from the application of synthetic chelates has led to the use of biodegradable complexes to correct Fe deficiency in plants. In this article, the Fe oxidation state, the Fe:ligand ratio, and the molecular weight distribution for heptagluconate (G7) and gluconate (G6) are considered as key factors for the efficacy of complexes as fertilizers. Complexes with different Fe:ligand ratios were prepared and analyzed by gel filtration chromatography (GFC). The ability of Fe:ligand ratios to provide Fe to tomato in hydroponics and soybean in calcareous soil was tested and compared with synthetic chelates (Fe3+:HBED and Fe3+:EDTA). RESULTS: G7 presented greater capacity to complex both Fe(II) and Fe(III) than G6, but the Fe(II) complexes exhibited poor stability at pH 9 and oxidation in solution. Gel filtration chromatography demonstrated the polynuclear nature of the Fe3+:G7 at various ratios. The effectiveness of the Fe fertilizers depend on the Fe3+:ligand ratio and the ligand type, the Fe3+:G7 (1:1 and 1:2) being the most effective. Fe3+:G7 (1:1) also presented a better response for the uptake of other micronutrients. CONCLUSION: Fe3+:G7 molar ratios have been shown to be critical for plant Fe uptake under hydroponic conditions and with calcareous soil. Thus, the Fe3+:G7 at equimolar ratio and 1:2 molar ratio can be an environmentally friendly alternative to less degradable synthetic chelates to correct Fe chlorosis in strategy I plantsThis work was supported by the State Research Agency, Ministry of Science, Innovation and Universities of Spain (projects AGL2013-44474-R and RTI2018-096268-B-I00) and the Comunidad de Madrid (Spain) and Structural Funds 2014-2020 (ERDF and ESF) (project AGRISOST-CM S2018/BAA-4330). SIV would like to thank the Consejo Nacional de Ciencia y Tecnología (CONACYT, Mexico) for supporting her grant through PhD studentship number 278934, and the Consejo de Ciencia, Tecnología e Innovación de Hidalgo (CITNOVA, Mexico

Local-flexural interactive buckling of standard and optimised cold-formed steel columns

This paper aims to study the interaction of local and overall flexural buckling in cold-formed steel (CFS) channels under axial compression. Detailed nonlinear FE models were developed and validated against a total of 36 axial compression tests on CFS plain and lipped channel columns with pin-ended boundary conditions. The numerical models incorporated the non-linear stress-strain behaviour of CFS material and enhanced properties of cold-worked corner regions obtained from coupon tests. The effects of initial geometric imperfections of the specimens measured by a specially designed set-up with laser displacement transducers were also taken into account. The developed FE models produced excellent predictions of the ultimate strength of the specimens obtained from experimental tests. The validated FE models and experimental results were then used to assess the adequacy of the effective width method in Eurocode 3 (EC3) and Direct Strength Method (DSM) in estimating the design capacity of a wide range of conventional and optimised design CFS channel column sections. The results indicate that Eurocode 3 provides conservative predictions (on average 21% deviation) for the compressive capacity of plain and lipped channel sections, while in general DSM predictions are more accurate for lipped channels. A comparison between FE predictions and tested results show that geometric imperfections can change the FE predictions by up to 20% and 40%, respectively, for lipped and plain channel columns, while the strain hardening effect at the rounded corner regions of the cross-sections is negligible. The results also confirmed that the proposed numerical model is able to provide a consistent and reliable prediction on the efficiency of a previously proposed optimisation methodology

Cyclic shear tests on RC precast beam-to-column connections retrofitted with a three-hinged steel device

Recent European earthquakes demonstrated that the seismic response of RC precast structures can be significantly influenced by the connection systems. Moreover, during past seismic events, many failures of the beam-to-column connections occurred due to their inadequate strength under seismic loads. The seismic safety of these connections has a crucial role in the overall seismic capacity of existing precast structures. A new connection system is employed as a retrofitting solution for a damaged beam-to-column connection and its cyclic shear performance is investigated by means of two cyclic shear tests on two different configurations. In both the experimental tests, the results demonstrate an efficient behavior of the retrofitted connections under horizontal cyclic loads. The comparison between the performance of the investigated connection and the response of a typical beam-to-column dowel connection allows to discuss the main critical features of the dowel connection system

Seismic response of Cfs strap-braced stud walls: Theoretical study

The use of cold-formed steel (CFS) profiles in low-rise residential buildings has increased in European construction sector. The reason of this interest is related to potentialities offered by this constructive system, which are the high structural performance, lightness, short construction time, durability and eco-efficiency. Nevertheless, the current structural codes, such as Eurocodes, do not provide enough information about the seismic design of this structural typology. In an effort to investigate the seismic response of CFS structures, a theoretical and experimental research has been carried out at University of Naples Federico II, with the main aim to support the spreading of these systems in seismic areas. This study focuses on an “all-steel design” solution in which strap-braced stud walls are the main lateral resisting system. In the present paper the outcomes of theoretical phase are shown with the aim of defining the criteria for the seismic design of such structures. In particular, a critical analysis of the requirements for CFS systems provided by the American code AISI S213 has been carried out by comparing it with those given by Eurocodes for traditional braced steel frames