An experimental study of steel fiber-reinforced high-strength concrete slender columns under cyclic loading

Structural engineers usually limit the use of HSC columns to seismic active zones because of their britle behavior in comparison with NSC, even though it presents advantages both in terms of mechanics and durability. A possible solution to improve the ductile behavior of HSC columns is the use of transverse reinforcement and steel fibers simultaneously. In addition, the use of HSC makes the design of more slender columns possible, with the consequent increase of second-order effects. However, there are few experimental tests on columns of medium slenderness (between 5 and 10) subjected to cyclic loads including or excluding steel fibers. This article presents experimental research work on the behavior of slender columns subjected to combined constant compression and cyclic lateral loads. Fifteen tests were carried out in order to study the behavior of such elements. The following variables were studied: concrete strength, slenderness, axial load level, transverse reinforcement ratio, and volumetric steel-fiber ratio. The maximum load and deformation capacity of the columns were analyzed. The fact that the inclusion of steel fibers into the concrete mixture increases the deformation capacity was verified. Moreover, a minimum transverse reinforcement is required in order to improve the effectiveness of the steel fibers with no significant decrease in the carrying capacity under cyclic loading. The inclusion of steel fibers in HSC can ensure similar ductility values to those of NSC. It was shown that slenderness influences the deformation capacity.Structural engineers usually limit the use of HSC columns to seismic active zones because of their britle behavior in comparison with NSC, even though it presents advantages both in terms of mechanics and durability. A possible solution to improve the ductile behavior of HSC columns is the use of transverse reinforcement and steel fibers simultaneously. In addition, the use of HSC makes the design of more slender columns possible, with the consequent increase of second-order effects. However, there are few experimental tests on columns of medium slenderness (between 5 and 10) subjected to cyclic loads including or excluding steel fibers. This article presents experimental research work on the behavior of slender columns subjected to combined constant compression and cyclic lateral loads. Fifteen tests were carried out in order to study the behavior of such elements. The following variables were studied: concrete strength, slenderness, axial load level, transverse reinforcement ratio, and volumetric steel-fiber ratio. The maximum load and deformation capacity of the columns were analyzed. The fact that the inclusion of steel fibers into the concrete mixture increases the deformation capacity was verified. Moreover, a minimum transverse reinforcement is required in order to improve the effectiveness of the steel fibers with no significant decrease in the carrying capacity under cyclic loading. The inclusion of steel fibers in HSC can ensure similar ductility values to those of NSC. It was shown that slenderness influences the deformation capacity

Behaviour of steel-fibre-reinforced normal-strength concrete slender columns under cyclic loading

The inclusion of ductility requirements is necessary to guarantee a safety design of concrete structures subjected to unexpected and/or reversal loads. It is important to outline that plastic hinges may develop in columns of reinforced concrete buildings, especially in column-foundation joints. The deformation capacity of the column depends on its slenderness. However, for the case of cyclic loading, few experimental tests of normal and fibre-reinforced concrete columns in the range of medium slenderness (between 5 and 10) have been performed. This paper presents an experimental research work on the behavior of slender columns subjected to combinations of constant axial and lateral cyclic loads. In order to study the behavior of this type of elements fourteen experimental tests are performed. The experimental results make it possible to calibrate numerical models, as well as, to validate simplified methods. The following variables are studied: slenderness, axial load level, volumetric transverse reinforcement ratio, and volumetric steel-fibre ratio. The maximum load and deformation capacity of the columns has been analyzed. It is interesting to note that ductility depends on the four tested variables analyzed. Moreover, the inclusion of steel-fibres into the concrete mixture increases the deformation capacity. In order to improve the steel fibres effectiveness the inclusion of a minimum transverse reinforcement is required. Thus, the column behavior suffers moderate strength losses due to cyclic loads. Finally, slenderness influences the deformation capacity if second-order effects are important, the cross-section has a ductile behavior, and materials capacity is reachedThe inclusion of ductility requirements is necessary to guarantee a safety design of concrete structures subjected to unexpected and/or reversal loads. It is important to outline that plastic hinges may develop in columns of reinforced concrete buildings, especially in column-foundation joints. The deformation capacity of the column depends on its slenderness. However, for the case of cyclic loading, few experimental tests of normal and fibre-reinforced concrete columns in the range of medium slenderness (between 5 and 10) have been performed. This paper presents an experimental research work on the behavior of slender columns subjected to combinations of constant axial and lateral cyclic loads. In order to study the behavior of this type of elements fourteen experimental tests are performed. The experimental results make it possible to calibrate numerical models, as well as, to validate simplified methods. The following variables are studied: slenderness, axial load level, volumetric transverse reinforcement ratio, and volumetric steel-fibre ratio. The maximum load and deformation capacity of the columns has been analyzed. It is interesting to note that ductility depends on the four tested variables analyzed. Moreover, the inclusion of steel-fibres into the concrete mixture increases the deformation capacity. In order to improve the steel fibres effectiveness the inclusion of a minimum transverse reinforcement is required. Thus, the column behavior suffers moderate strength losses due to cyclic loads. Finally, slenderness influences the deformation capacity if second-order effects are important, the cross-section has a ductile behavior, and materials capacity is reache

Ultimate capacity of rectangular concrete-filled steel tubular columns under unequal load eccentricities

The paper describes 36 experimental tests conducted on rectangular and square tubular columns filled with normal and high strength concrete and subjected to a non-constant bending moment distribution with respect to the weak axis. The test parameters were the nominal strength of concrete (30 and 90 MPa), the cross-section aspect ratio (square or rectangular), the thickness (4 or 5 mm) and the ratio of the top and bottom first order eccentricities e top/e bottom (1, 0.5, 0 and - 0.5). The ultimate load of each test was compared with the design loads from Eurocode 4, presenting unsafe results inside a 10% safety margin. The tests show that the use of high strength concrete is more useful for the cases of non-constant bending moment, whereas if the aim is to obtain a more ductile behavior the use of concrete-filled columns is more appealing in the cases of normal strength concrete with non-constant bending moments because, although they resist less axial force than the members with HSC, they obtain a softened post-peak behavior. © 2011 Elsevier Ltd.The authors wish to express their sincere gratitude to the Spanish Ministry of Education for the help provided through projects BIA2005_255 and BIA2009_9411, and to the European Community for FEDER funds.Hernández Figueirido, D.; Romero, ML.; Bonet Senach, JL.; Montalva Subirats, JM. (2012). Ultimate capacity of rectangular concrete-filled steel tubular columns under unequal load eccentricities. Journal of Constructional Steel Research. 68(1):107-117. https://doi.org/10.1016/j.jcsr.2011.07.014S10711768

Gold-Based Nanoparticles on Amino-Functionalized Mesoporous Silica Supports as Nanozymes for Glucose Oxidation

The transformation of glucose represents a topic of great interest at different levels. In the first place, glucose is currently conceived as a green feedstock for the sustainable production of chemicals. Secondly, the depletion of glucose at the cellular level is currently envisioned as a promising strategy to treat and alter the erratic metabolism of tumoral cells. The use of natural enzymes offers multiple advantages in terms of specificity towards the glucose substrate but may lack sufficient robustness and recyclability beyond the optimal operating conditions of these natural systems. In the present work, we have evaluated the potential use of an inorganic based nanohybrid containing gold nanoparticles supported onto ordered mesoporous supports. We have performed different assays that corroborate the enzyme-mimicking response of these inorganic surrogates towards the selective conversion of glucose into gluconic acid and hydrogen peroxide. Moreover, we conclude that these enzyme-like mimicking surrogates can operate at different pH ranges and under mild reaction conditions, can be recycled multiple times and maintain excellent catalytic response in comparison with other gold-based catalysts

Platinum-based nanodendrites as glucose oxidase-mimicking surrogates

Catalytic conversion of glucose represents an interesting field of research with multiple applications. From the biotechnology point of view, glucose conversion leads to the fabrication of different added-value by-products. In the field of nanocatalytic medicine, the reduction of glucose levels within the tumor microenvironment (TME) represents an appealing approach based on the starvation of cancer cells. Glucose typically achieves high conversion rates with the aid of glucose oxidase (GOx) enzymes or by fermentation. GOx is subjected to degradation, possesses poor recyclability and operates under very specific reaction conditions. Gold-based materials have been typically explored as inorganic catalytic alternatives to GOx in order to convert glucose into building block chemicals of interest. Still, the lack of sufficient selectivity towards certain products such as gluconolactone, the requirement of high fluxes of oxygen or the critical size dependency hinder their full potential, especially in liquid phase reactions. The present work describes the synthesis of platinum-based nanodendrites as novel enzyme-mimicking inorganic surrogates able to convert glucose into gluconolactone with outstanding selectivity values above 85%. We have also studied the enzymatic behavior of these Pt-based nanozymes using the Michaelis–Menten and Lineweaver–Burk models and used the main calculation approaches available in the literature to determine highly competitive glucose turnover rates for Pt or Pt–Au nanodendrites

A Note on the Spectrum of Composition Operators on Spaces of Real Analytic Functions

[EN] In this paper the spectrum of composition operators on the space of real analytic functions is investigated. In some cases it is completely determined while in some other cases it is only estimated.The research of the authors was partially supported by MEC and FEDER Project MTM2013-43540-P and the work of of Bonet by the Grant GV Project Prometeo II/2013/013. The research of Domanski was supported by National Center of Science, Poland, Grant No. DEC-2013/10/A/ST1/00091.Bonet Solves, JA.; Domanski, P. (2017). A Note on the Spectrum of Composition Operators on Spaces of Real Analytic Functions. Complex Analysis and Operator Theory. 11(1):161-174. https://doi.org/10.1007/s11785-016-0589-5S161174111Belitskii, G., Lyubich, Y.: The Abel equation and total solvability of linear functional equations. Studia Math. 127, 81–97 (1998)Belitskii, G., Lyubich, Y.: The real analytic solutions of the Abel functional equation. Studia Math. 134, 135–141 (1999)Belitskii, G., Tkachenko, V.: One-Dimensional Functional Equations. Springer, Basel (2003)Belitskii, G., Tkachenko, V.: Functional equations in real analytic functions. Studia Math. 143, 153–174 (2000)Bonet, J., Domański, P.: Power bounded composition operators on spaces of analytic functions. Collect. Math. 62, 69–83 (2011)Bonet, J., Domański, P.: Hypercyclic composition operators on spaces of real analytic fucntions. Math. Proc. Cambridge Phil. Soc. 153, 489–503 (2012)Bonet, J., Domański, P.: Abel’s functional equation and eigenvalues of composition operators on spaces of real analytic functions. Integr. Equ. Oper. Theor. 81, 455–482 (2015). doi: 10.1007/s00020-014-2175-4Cartan, H.: Variétés analytiques réelles et variétés analytiques complexes. Bull. Soc. Math. France 85, 77–99 (1957)Domański, P.: Notes on real analytic functions and classical operators, Topics in Complex Analysis and Operator Theory (Winter School in Complex Analysis and Operator Theory, Valencia, February 2010), Contemporary Math. 561 (2012) 3–47. Amer. Math. Soc, Providence (2012)Domański, P., Goliński, M., Langenbruch, M.: A note on composition operators on spaces of real analytic functions. Ann. Polon. Mat. 103, 209–216 (2012)Domański, P., Langenbruch, M.: Composition operators on spaces of real analytic functions. Math. Nachr. 254–255, 68–86 (2003)Domański, P., Langenbruch, M.: Coherent analytic sets and composition of real analytic functions. J. reine angew. Math. 582, 41–59 (2005)Domański, P., Langenbruch, M.: Composition operators with closed image on spaces of real analytic functions. Bull. Lond. Math. Soc. 38, 636–646 (2006)Domański, P., Vogt, D.: The space of real analytic functions has no basis. Studia Math. 142, 187–200 (2000)Hörmander, L.: An Introduction to Complex Analysis in Several Variables. North Holland, Amsterdam (1986)Meise, R., Vogt, D.: Introduction to Functional Analysis. Clarendon, Oxford (1997)Smajdor, W.: On the existence and uniqueness of analytic solutions of the functional equation $$\varphi (z)=h(z,\varphi [f(z)])$$ φ ( z ) = h ( z , φ [ f ( z ) ] ) . Ann. Polon. Math. 19, 37–45 (1967

Inelastic Effective Length Factor of Nonsway Reinforced Concrete Columns

[EN] This paper proposes a new equation for the effective length factor k-factor for reinforced concrete columns in braced frames. The new formula is valid both for normal and high-strength concrete. The equation was obtained from a sensitivity analysis performed on a two-dimensional nonlinear finite-element numerical model that takes into account the inelastic behavior of the concrete columns cracking, yielding, and second order effects. The numerical model was calibrated with 44 experimental tests performed by the writers¿ research group. A comparative study was carried out between the numerical model and different national design codes, displaying important differences with respect to all of them: the ACI code from 37 to 3%, the Spanish code EHE from 26 to 9.26%, and the Eurocode 2 from 14 to 14%. It was decided to propose two additional simplified equations: one for checking and the second for design.The authors wish to express their sincere gratitude to the Spanish Ministerio de Fomento for help provided through project 13-12-2001 and Ministerio de Educación through BIA2005-255.Bendito, A.; Romero, ML.; Bonet Senach, JL.; Miguel Sosa, P.; Fernández Prada, MÁ. (2009). Inelastic Effective Length Factor of Nonsway Reinforced Concrete Columns. Journal of Structural Engineering. 135(9):1034-1039. https://doi.org/10.1061/(ASCE)0733-9445(2009)135:9(1034)S10341039135

Application of Project-Based Learning in the development of a Bachelor’s Thesis in the Bachelor’s Degree in Civil Engineering

El Aprendizaje Basado en Proyectos (ABP) es un enfoque educativo que consigue motivar al alumnado a través de su implicación activa en el desarrollo de un trabajo que tiene un alto componente práctico. En consecuencia, se genera un aprendizaje profundo de los temas tratados. Con la finalidad de alcanzar estas metas, se aplicó el ABP al Trabajo Final de Grado (TFG) de cuatro alumnos del Grado en Ingeniería Civil de la Universitat Politècnica de València. El trabajo realizado consistió en el diseño, construcción, ensayo y análisis de un modelo reducido de una estructura de hormigón armado. La metodología empleada consistió en la definición de las actividades prácticas y teóricas necesarias para desarrollar el proyecto sobre el elemento estructural y el establecimiento de un sistema de seguimiento por parte del tutor. Los resultados obtenidos demuestran el buen funcionamiento de la innovación, que consiguió motivar a los alumnos, potenciar su aprendizaje y facilitar el alcance de las competencias establecidas en el TFG y otras propias de la titulación, así como despertar el interés de los alumnos por el cálculo de estructuras de hormigón.Project-Based Learning (PBL) is an educational approach that motivates students through their active involvement in the development of a highly practical assignment. As a result, a deep learning process is generated. In order to achieve these goals, PBL was applied to the Bachelor’s Thesis (BT) of four students of the Degree in Civil Engineering of the Universitat Politècnica de València. The work consisted of the design, construction, testing and analysis of a scaled-down model of a reinforced concrete structure. The methodology used consisted of defining the practical and theoretical activities necessary to develop the project on the structural element and the establishment of a monitoring system by the tutor. The results obtained demonstrate the good performance of the innovation, which motivated the students, enhanced their learning and facilitated the achievement of the competences established in the BT and others specific to the degree, as well as awakened the students' interest in the calculation of concrete structures

A note on completeness of weighted normed spaces of analytic functions

[EN] Given a non-negative weight v, not necessarily bounded or strictly positive, defined on a domain G in the complex plane, we consider the weighted space H-v(infinity) (G)of all holomorphic functions on G such that the product v vertical bar f vertical bar is bounded in G and study the question of when such a space is complete under the canonical sup-seminorm. We obtain both some necessary and some sufficient conditions in terms of the weight v, exhibit several relevant examples, and characterize completeness in the case of spaces with radial weights on balanced domains.The first author was partially supported by MTM2013-43540-P and MTM2016-76647-P by MINECO/FEDER-EU and GVA Prometeo II/2013/013. The second author was partially supported by the MINECO/FEDER-EU Grant MTM2015-65792-P. Both authors were partially supported by Thematic Research Network MTM2015-69323-REDT, MINECO, Spain.Bonet Solves, JA.; Vukotic, D. (2017). A note on completeness of weighted normed spaces of analytic functions. Results in Mathematics. 72(1-2):263-279. https://doi.org/10.1007/s00025-017-0696-2S263279721-2Arcozzi, N., Björn, A.: Dominating sets for analytic and harmonic functions and completeness of weighted Bergman spaces. Math. Proc. R. Ir. Acad. 102A, 175–192 (2002)Berenstein, C.A., Gay, R.: Complex Variables, An Introduction. Springer, New York (1991)Bierstedt, K.D., Bonet, J., Galbis, A.: Weighted spaces of holomorphic functions on bounded domains. Mich. Math. J. 40, 271–297 (1993)Bierstedt, K.D., Bonet, J., Taskinen, J.: Associated weights and spaces of holomorphic functions. Stud. Math. 127, 137–168 (1998)Björn, A.: Removable singularities for weighted Bergman spaces. Czechoslov. Math. J. 56, 179–227 (2006)Bonet, J., Domański, P., Lindström, M.: Essential norm and weak compactness of composition operators on weighted Banach spaces of analytic functions. Can. Math. Bull. 42(2), 139–148 (1999)Bonet, J., Vogt, D.: Weighted spaces of holomorphic functions and sequence spaces. Note Mat. 17, 87–97 (1997)Conway, J.B.: Functions of One Complex Variable, Second Edition, Graduate Texts in Mathematics, vol. 11. Springer, New York (1978)Gaier, D.: Lectures on Complex Approximation. Birkhäuser, Boston (1987)Grosse-Erdmann, K.-G.: A weak criterion for vector-valued holomorphic functions. Math. Proc. Camb. Philos. Soc. 136, 399–411 (2004)Hörmander, L.: An Introduction to Complex Analysis in Several Variables. North-Holland, Amsterdam (1979)Horváth, J.: Topological Vector Spaces and Distributions. Addison-Wesley, Reading (1966)Lusky, W.: On weighted spaces of harmonic and holomorphic functions. J. Lond. Math. Soc. 51, 309–320 (1995)Lusky, W.: On the isomorphism classes of weighted spaces of harmonic and holomorphic functions. Stud. Math. 175, 19–45 (2006)Nakazi, T.: Weighted Bloch spaces which are Banach spaces. Rend. Circ. Mat. Palermo 62, 427–440 (2013)Shields, A.L., Williams, D.L.: Bounded projections, duality and multipliers in spaces of analytic functions. Trans. Am. Math. Soc. 162, 287–302 (1971

Inter-individual different responses to continuous and interval training in recreational middle-aged women runners

A crucial subject in sports is identifying the inter-individual variation in response to training, which would allow creating individualised pre-training schedules, improving runner's performance. We aimed to analyse heterogeneity in individual responses to two half-marathon training programmes differing in running volume and intensity in middle-aged recreational women. Twenty women (40±7 years, 61±7kg, 167±6cm, VO2max=48±6 mL·kg-1·min-1) underwent either moderate-intensity continuous (MICT) or high-intensity interval (HIIT) 12-week training. They were evaluated before and after training with maximal incremental tests in the laboratory (VO2max) and in the field (time to exhaustion, TTE; short interval series and long run). All the women participated in the same half-marathon and their finishing times were compared with their previous times. Although the improvements in the mean finishing times were not significant, MICT elicited a greater reduction (3min 50s, P=0.298), with more women (70%) improving on their previous times, than HIIT (reduction of 2min 34s, P=0.197, 50% responders). Laboratory tests showed more differences in the HIIT group (P=0.008), while both groups presented homogeneous significant (P<0.05) increases in TTE. Both in the short interval series and in the long run, HIIT induced better individual improvements, with a greater percentage of responders compared to MICT (100% versus 50% in the short series and 78% versus 38% in the long run). In conclusion, variability in interindividual responses was observed after both MICT and HIIT, with some participants showing improvements (responders) while others did not (non-responders) in different performance parameters, reinforcing the idea that individualised training prescription is needed to optimise performance