Analysis of FRP shear strengthening solutions for reinforced concrete beams considering debonding failure

In this paper, a fiber beam model previously developed by the authors for the nonlinear analysis of strengthened elements, including the effects of shear, is used to predict the response of reinforced concrete (RC) beams strengthened in shear with fiber reinforced polymers (FRP) sheets. In the previous version of the model, debonding failure of FRP was not included; hence, its application was limited to the simulation of wrapped configurations. The model is now extended to account for debonding failure in order to allow for its application to beams strengthened with U-shaped and side-bonded configurations. Existing experimental tests on RC beams strengthened in shear by FRP sheets in both wrapped and U-shaped configurations were numerically simulated. The model reproduces, with reasonable accuracy, the experimental failure loads, the load-deflection behavior, and the strains in FRP and stirrups with increasing load. The advantages of this proposal are related with the simplicity and straightforwardness of the beam models to be applied in practical engineering problems.Peer ReviewedPostprint (author's final draft

Grafting melons onto potential cucumis spp. rootstocks

Cucumís melo is an economically importar]t crop. Its culture is hampered by differen t types of soil stresses. Grafting melons onto different resistant cucurbits belonging to the genera, Cucurbíta, Lagenaría, Luffa, etc. have been successfully used to avoid these problems. However, me Ion quality has been nega.tively modified as a consequence of grafting. In general, variation in fruit shape, seed cavity and sugar content have been observed. The use of rootstocks more genetically c\oser to the melon scions could be useful to obtain fru i ts with better quality from melon grafted plantsPostprint (published version

Programación didáctica 2º de ESO Física y Química

Treball Final de Màster Universitari en Professor/a d'Educació Secundària Obligatòria i Batxillerat, Formació Professional i Ensenyaments d'Idiomes. Codi SAP119. Curs: 2019/2020El siguiente documento presenta el trabajo de final de Máster correspondiente al Máster Universitario en Profesor/a de Educación Secundaria Obligatoria y Bachillerato, Formación Profesional y Enseñamiento de Idiomas. Este documento se basa en la modalidad 3, planificación curricular, que tiene como objetivo la creación y diseño de una programación didáctica. La programación didáctica que se describe está ubicada en un trimestre para un curso de 2º de ESO. Se encuentra formada por 2 unidades didácticas, las cuales engloban 1 de los 5 bloques que se presentan en el Real Decreto 1105/2014, definidos en la asignatura de Física y Química. Para la planificación de las diferentes actividades, durante ambas unidades didácticas, se han utilizado metodologías y recursos adaptándolos al contenido que se ha de trabajar. Utilizando el trabajo cooperativo, el flipped – classroom y la participación activa de todo el alumnado, se ha intentado hacer una aproximación de la Física y Química, construyendo un ambiente y unos nuevos conocimientos de una forma diferente y divertida. Finalmente, se evalúa al alumnado con diferentes instrumentos, los cuales nos permiten ver los diferentes grados de aprendizaje que hay, siguiendo en todo momento los indicadores de logro y los criterios de evaluación que se describen en el Real Decreto 1105/2014. Será con las pruebas de evaluación tradicional, los exámenes, quienes nos darán las evidencias del alcance total de las competencias clave

Contribution of externally bonded FRP shear reinforcement to the shear strength of RC beams

An experimental program of T-beams strengthened in shear by CFRP sheets has been developed with two longitudinal reinforcement ratios and different externally bonded CFRP shear strengthening amounts in a discontinuous or continuous U-shaped configuration with and without mechanical anchorages. The effectiveness of the external reinforcement without anchorages was low regardless the CFRP reinforcement ratio. There is an evidence of the interaction of the different shear strength components, concrete Vc, transverse steel Vs, CFRP sheets Vf that have been obtained from the registered data of the instrumentation. This interaction might explain that the ultimate shear force of some CFRP-strengthened beams was lower than the one of the control beam. There is a significant difference between the sum of the Vc, Vs, and Vf components and the total shear force. This difference is assumed to be carried out by the flange (including its internal transverse reinforcement), which represents a significant percentage of the total shear strength (with a mean value of 38%). Finally, the contribution of the CFRP has been obtained by different existing guidelines and has been compared to the experimental values.Peer ReviewedPostprint (author's final draft

Refuerzo de estructuras de hormigón armado con laminados de fibra de carbono (CFRP)

El uso de los materiales compuestos en el campo del refuerzo estructural ha experimentado un notable crecimiento en los últimos años gracias a sus elevadas relaciones resistencia/peso y rigidez/peso, que permiten reducir costes de mano de obra respecto al empleo de otros materiales más convencionales. Los polímeros reforzados con fibras (FRP) se pueden aplicar como refuerzo de estructuras de hormigón armado o pretensado a flexión, cortante o confinamiento. Independientemente del tipo de refuerzo, uno de los principales inconvenientes o condicionantes en el dimensionamiento es el fallo por el desprendimiento prematuro del refuerzo, antes de alcanzar la resistencia última del mismo, por la concentración de tensiones en la interfase entre el laminado y el soporte

The compression chord capacity model for the shear design and assessment of reinforced and prestressed concrete beams

This is the accepted version of the following article: [Cladera, A., Marí, A., Bairán, J. M., Ribas, C., Oller, E. and Duarte, N. (2016), The compression chord capacity model for the shear design and assessment of reinforced and prestressed concrete beams. Structural Concrete, 17: 1017–1032. doi:10.1002/suco.201500214], which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/suco.201500214/fullA simplified mechanical model is presented for the shear strength prediction of reinforced and prestressed concrete members with and without transverse reinforcement, with I, T or rectangular cross-section. The model, derived with further simplifications from a previous one developed by the authors, incorporates the contributions of the concrete compression chord, the cracked web, the dowel action and the shear reinforcement in a compact formulation. The mechanical character of the model provides valuable information about the physics of the problem and incorporates the most relevant parameters governing the shear strength of structural concrete members. The predictions of the model fit very well the experimental results collected in the ACI-DAfStb databases of shear tests on slender reinforced and prestressed concrete beams with and without stirrups. Due to this fact and the simplicity of the derived equations it may become a very useful tool for structural design and assessment in engineering practice.Peer ReviewedPostprint (author's final draft

Health Determinants Associated with the Mediterranean Diet: A Cross-Sectional Study

Introduction: The Mediterranean diet (MD) has been shown to be a good tool for the prevention of obesity and other chronic noncommunicable diseases (NCDs) and to have a low environmental impact. The aim of the present study was to evaluate the relationship between declared morbidity, lifestyles and other sociodemographic factors with high adherence to the MD (AMD) in an adult population in southeastern Spain. Material and Methods: We conducted a cross-sectional study of a sample (n = 2728) representative of a non-institutionalized population ≥16 years. The data corresponded to the 2010-11 Nutrition Survey of the Valencian Community. The AMD was assessed using the Mediterranean Diet Adherence Screener questionnaire. The association of variables and high AMD was assessed by univariate and multivariate logistic regression determining crude and adjusted odds ratios. Results: Multivariate analysis showed that age 45 years or older, living with a partner, eating between meals, and not smoking were associated with high AMD. The age groups 45–64 years and 65 years or older showed the strongest association with high AMD in both sexes. Conclusion: The investigation showed a generational loss of AMD. People older than 45 years and living in company are more likely to adhere to DM, the risk group being young people living alone and smokers

Evaluación de la eficiencia de soluciones de refuerzo en estructuras de hormigón mediante análisis no lineal evolutivo

When designing a structural strengthening solution, the influence of the previous state of the structure on the capacity of the strengthened structure must be evaluated. In addition, strengthening interventions may involve operations such as partial unloading of the structure, placement and removal of temporary shores, application of loads or pre-deformations, restoring of damaged reinforcement or spalled con-crete or constraining of lateral strains. Therefore, changes in the cross-section geometry and reinforcement, longitudinal scheme, support conditions, loads and state of stresses and strains, may take place. Furthermore, occurrence of phenomena producing a premature failure or a change in the failure mode, should be avoided. In order to account for such a large variety of causes and phenomena affecting the structural response, a nonlinear and time-dependent analysis model of 3D reinforced and prestressed concrete frames, capable of capturing different failure modes and taking into account the structural history, is described. The model has been verified with tests on strengthened structures available in the literature and has been applied to an actually remodeled structure, comparing the advantages and disadvantages of two different strengthening proposals, showing its capabilities to assess the efficiency of structural strengthening systems.This paper is dedicated to the memory of an extraordinary engineer and human being, Luis Ortega Basagoiti, who was an example and reference for structural engineers and researchers along his professional career. The works described in this paper have been developed in the framework of the following research projects funded by the Spanish Science and Technology Ministries and by the European Funds for Regional Development, ADRESS (BIA2009-11764), REHABCAR (IPT-370000-2010-029), HORVITAL (BIA2015-64672-C4-1-R) and STRADURAVIUS (RTI2018-097314-B-C21).Peer ReviewedPostprint (published version

Experimental investigation of the shear strength of one-way reinforced concrete (RC) slabs subjected to concentrated loads and in-plane transverse axial tension

This paper presents the results of an experimental campaign carried out to investigate the effects of in-plane transverse tensile forces on the shear strength of linearly supported one-way reinforced concrete (RC) slabs without shear reinforcement subjected to concentrated loads. A total of 5 half scale slabs (1650¿×¿1650¿×¿120¿mm), subjected simultaneously to different levels of in-plane tensile forces and a concentrated load were tested up to failure. The clear shear span to effective depth ratio av/d was equal to 3 in all tests, to minimize the effects of the direct transmission of the load to the closest support, the so called arching action. As observed, the shear strength barely decreases with increasing values of the tensile force applied, even for values of the external force that cracked the concrete cross-section of the slabs in the direction perpendicular to the span. These observations may indicate that the shear–flexural behavior in the spanning direction is not significantly affected by the membrane forces in the transverse direction.This work has been carried out within the framework of the research project BIA-2015-64672-C4-1-R, financed by the Ministry of Economy and Competitiveness (MINECO) of Spain, and with the invaluable help of the technicians and the director of the Laboratory of Technology of Structures and Materials of the Universitat Politècnica de Catalunya. The authors want also to thank Master students Pau Figueras and Laura Beltran who collaborated in the numerical predictions and execution of the tests, respectively.Peer ReviewedPostprint (published version

Performance-based slenderness limits for deformations and crack control of reinforced concrete flexural members

The use of high strength materials allows flexural members to resist the design loads or to cover long spans with a reduced depth. However, the strict cross section dimensions and reinforcement amount required in ULS are often insufficient to satisfy the serviceability limit states. Due to the complexity associated to a rigorous computation of deflections and cracks width in cracked RC members along their service life, an effective way to ensure the satisfaction of the SLS is to limit the slenderness ratio l/d of the element. In the present study, the slenderness limit concept, previously used for deflection control, is generalized to incorporate the crack width limitations in the framework of structural performance-based design. Equations for slenderness limits incorporating the main parameters influencing the service behaviour of RC members are derived. Cracking and long-term effects are accounted for through simplified coefficients derived from structural concrete mechanics and experimental observations. The proposed slenderness limits are compared with those derived from a numerical non-linear time-dependent analysis for two case studies, and also with those obtained using the EC2 procedure for deflection calculation in terms of constant applied load and constant reinforcement strain. Very good results have been obtained in terms of low errors and scatter, showing that the proposed slenderness limits are a useful tool for performance-based design of RC structures.Peer ReviewedPostprint (author's final draft