Habitat and habitants in the Catalan Pyrenees: dynamics and policies for under-populated high-mountain villages

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Safety Assessment of Shear Strength Current Formulations for Composite Concrete Beams without Web Reinforcement

[EN] Construction with precast concrete elements without web reinforcement and cast-in-place concrete on them to enhance the overall structure's integrity is a widespread practice in building construction. However as these composite elements' vertical shear strength has not been studied in-depth, a clear criterion about cast-in-place concrete's contribution to shear resistance is still a pending matter. The present study intends to reach practical conclusions about the shear strength assessment of composite concrete elements without web reinforcement. To do so, the shear strengths of 36 specimens, provided by existing shear formulations, were compared: 19 specimens tested by the authors, in which the existence of an interface between concretes, the cross-sectional shape and the concrete compressive strengths of the beam and slab were studied; and 17 specimens taken from a previous study about composite elements by Kim et al. (2016). The applied shear formulations were those of EC2-04, Draft 7 of EC2-20, fib MC-10, ACI 318-19 and the model proposed by Kim et al. (2016). Firstly, specimens' shear strength was calculated by considering that only the beam resisted shear. Secondly according to ACI 318-19 indications about assessing composite elements¿ shear strength, the entire composite element's effective depth was used considering the lower of the compressive strengths of the beam's and slab's concretes and the weighted average of the compressive strengths. Additionally,the entire effective depth and the beam's concrete compressive strength were used. Codes formulations were more precise when estimating the monolithic specimens' shear strengths than those of composites. Therefore, the development of an adapted methodology to assess these elements¿ shear strengths is needed. EC2-20 obtained the most accurate results and gave quite good estimations for composite elements when the entire effective depth and weighted average of the concretes compressive strengths were considered.This study forms part of the research conducted at the Concrete Science and Technology University Institute (ICITECH) of the Universitat Politècnica de València (UPV, Spain) with concrete supplied by Caplansa. The project has been supported by the Spanish Ministry of Science and Innovation through Projects BIA2015-64672-C4-4-R and RTI2018-099091-B-C21-AR; the Regional Government of Valencia through Project AICO/2018/250, and the European Union with FEDER funds. The authors thank the Spanish Ministry of Economy and Business for Grant BES-2016-078010.Rueda-García, L.; Bonet Senach, JL.; Miguel Sosa, P.; Fernández Prada, MÁ. (2021). Safety Assessment of Shear Strength Current Formulations for Composite Concrete Beams without Web Reinforcement. Fédération Internationale du Béton (fib) - International Federation for Structural Concrete. 1-10. http://hdl.handle.net/10251/182209S11

A simplified method to predict the ultimate shear stress of reinforcedconcrete membrane elements

This paper presents a new simplified verification method to predict the ultimate shear stress and the mode of failure of reinforced concrete membrane elements with orthogonal reinforcement under any combination of normal stresses. This method is based on a simplified model designed to take the condition of the concrete at failure into account. The methodology is non-iterative, simple and easy to use for practical purposes. The accuracy of the verification method has been checked using test results from 88 RC membrane elements subjected to a wide range of in-plane normal and shear stresses, concrete strengths, and reinforcement ratios for both x and y directions. Moreover, the proposed method is compared with MCFT using Membrane-2000 software and other simplified methods (SMCS by Rahal 2010, the Marti-Kauffman method 1998 and the Mancini proposal 2001). The proposed method strikes a balance between a general view, accuracy and simplicity, using a wide range of tests that cover different modes of failure.The authors of this work wish to thank the research bureau of the Spanish Ministry of Science and Innovation for the funding of the projects BIA 2009-10207 and BIA 2009-11369, and the Universitat Politecnica de Valencia for the funding through the Programa de Apoyo a la Investigacion y Desarrollo (PAID-06-11).Miguel Sosa, P.; Navarro-Gregori, J.; Fernández Prada, MÁ.; Bonet Senach, JL. (2013). A simplified method to predict the ultimate shear stress of reinforcedconcrete membrane elements. Engineering Structures. 49:329-344. https://doi.org/10.1016/j.engstruct.2012.11.009S3293444

Multicentric recurrent parotid pleomorphic adenoma in a child

Mixed tumours of the parotid gland are rare in childhood and recurrence of this tumour is infrequent. Some authors report a higher rate of recurrence with some histological subtypes, like hypocellular variant. Female sex and young age at initial treatment are also risk factor for recurrence. Also the first surgical treatment, tumour enucleation or parotidectomy, has been implicated as a cause for recurrence. We present a case of a multicentric doubly recurrent parotid pleomorphic adenoma, 7 and 14 years after tumour enucleation, in a 9-year-old child. All the nodules resected showed the hypocellular variant of pleomorphic adenoma. We consider the relationships between the choice of treatment, the histologic subtypes of pleomorphic adenomas and multifocal tumours and recurrence. In this case, we believe the recurrence was related to surgical enucleation previously performed and the hypocellular histological subtype. We conclude that tumour enucleation is a risk factor for recurrence and total parotidectomy is the treatment of choice for pleomorphic parotid adenoma also in childhood

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