Advanced FE models of stiffened cleat angle connections

Congreso celebrado en la Escuela de Arquitectura de la Universidad de Sevilla desde el 24 hasta el 26 de junio de 2015.In this paper, the development of reliable 3D FE models of stiffened angle connections is dealt with. These advanced models will permit to obtain the assessment of the 3D deformational response of some future tests. Abaqus® finite element code was used to carry the 3D finite element analyses out. Symmetry was considered for these numerical analyses so a quarter of the geometry was modelled. The results obtained are compared with those from the analysis of the analogous specimens but without the top angle stiffener, showing an important increase in the initial connection stiffness. At the same time, the stress increment in the column panel zone due to the presence of the angle stiffener has been discussed

A new analytical formulation for the stiffness and resistance of the additional plate in bending in beam‐to‐beam steel joints

[Abstract] This paper focuses on the stiffness and resistance of the additional plate in bending. This is a component which appears in beam-to-beam bolted steel joints, when a secondary beam with a flush end plate is attached orthogonally to the primary beam by an additional plate welded between its flanges. In this work, six experimental tests have been carried out to calibrate a finite element model which has been used to develop a wide parametric study. Thus, a new formulation for stiffness and resistance based on an equivalent frame is proposed.The financial support provided by the Spanish Ministerio de Economía y Competitividad and Fondo Europeo de Desarrollo Regional under contract BIA2016-80358-C2-2-P MINECO/FEDER UE is gratefully acknowledged

Experimental evaluation, FEM and condensed stiffness matrices of 2D external welded haunched joints

Manuscrito aceptado[Abstract] In recent years, several researchers have been working hard to improve the knowledge with respect to steel joints behaviour. Special effort has been made for obtaining the stiffness of the different components of the joints, with the aim of introducing this stiffness in the component method in accordance with the EC3. Nevertheless, the component method has important limitations and therefore it is necessary to develop new methods for obtaining the stiffness of joints. In the present work, an alternative method of evaluating the stiffness of 2D external welded haunched joints is presented. The authors show the results of 4 tests and their corresponding finite element models. Four different typologies of joints have been tested, in regards to the stiffening of the column web. The four configurations of joints are the following: Joint 1: with three horizontal stiffeners in the column web. Joint 2: with two horizontal stiffeners and an inclined stiffener in the column web. Joint 3: with two horizontal stiffeners in the column web. Joint 4: without web stiffeners. In all cases, the specimens have been subjected to a point load at the end of the beam, and rotations and displacements have been measured. Additionally, finite element models of the joints have been developed, and they have been properly calibrated with the results obtained in the tests. The condensed stiffness matrices of the joints have been extracted, and they have been tested by means of introducing such matrices into the global analysis of 4 frames, and comparing the obtained results with those ones extracted from the corresponding finite element models. The use of the condensed matrix of the joints presents very good results, and takes into account all the interactions between the different degrees of freedom of the joint.The research described in this paper was financially supported by the Spanish Ministry of Economy and Competitiveness under contract BIA2016-80358-C2-2-P MINECO/FEDER, UE

Artificial neural network prediction of the initial stiffness of semi-rigid beam-to-column connections

[Abstract]: Joints are significant components in the design and construction of steel structures. The characteristic parameters of the connections must be reproduced in a reliable way to represent the actual behaviour of a structure. Accordingly, the study of semi-rigid joints is essential to better understand this issue. Among the different types of semi-rigid joints, angle connections stand out as a suitable solution in many cases. This paper presents a methodology using artificial neural networks for predicting the initial rotational stiffness of major axis symmetrical angle connections according to the Eurocode description. A consistent stiffness database was developed from the existing data in the Steel Connection Data Bank. Then, the database was cleansed to provide with a robust training set. Different network architectures were analysed until a topology that showed a good performance and generalisation features was obtained. The network was successfully checked with some saved tests from the database and with off-database tests; the network could be reliably used within the range of the training input parameters.Ministerio de Ciencia e Innovación; PID2020-113895GBC3

Towards an optimal adaptation of exposure to NOAA assessment methodology in Multi-Source Industrial Scenarios (MSIS): the challenges and the decision-making process

It is expected a progressive increase of the industrial processes that manufacture of intermediate (iNEPs) and end products incorporating ENMs (eNEPs) to bring about improved properties. Therefore, the assessment of occupational exposure to airborne NOAA will migrate, from the simple and well-controlled exposure scenarios in research laboratories and ENMs production plants using innovative production technologies, to much more complex exposure scenarios located around processes of manufacture of eNEPs that, in many cases, will be modified conventional production processes. Here will be discussed some of the typical challenging situations in the process of risk assessment of inhalation exposure to NOAA in Multi-Source Industrial Scenarios (MSIS), from the basis of the lessons learned when confronted to those scenarios in the frame of some European and Spanish research projects.This paper exploits the results of the research developed by projects SCAFFOLD and EHS Advance. Project SCAFFOLD received funding from the European Union's FP7 research and innovation programme, under grant agreement No. 280535. Project EHS Advance received funding from the Basque Government research programme (Etortek). The authors would also like to express their grateful to companies BOSTLAN (Bizkaia, Spain) and TECNAN (Navarra, Spain) for the support provided to carry out the exposure measurements in their respective facilities

Note on "An efficient approach for solving the lot-sizing problem with time-varying storage capacities"

In a recent paper Gutiérrez et al. (2008) show that the lot-sizing problem with inventory bounds can be solved in O(T log T) time. In this note we show that their algorithm does not lead to an optimal solution in general

Acute toxicity, bioaccumulation and effects of dietary 1 transfer of silver from brine 2 shrimps exposed to PVP/PEI-coated silver nanoparticles to zebrafish

The extensive use and release to the aquatic environment of silver nanoparticles (NPs) could lead to their incorporation into the food web. Brine shrimp larvae of 24 h showed low sensitivity to the exposure to PVP/PEI-coated Ag NPs (5 nm), with EC50 values at 24 h of 19.63 mg Ag L-1, but they significantly accumulated silver after 24 h of exposure to 100 μg L-1 of Ag NPs. Thus, to assess bioaccumulation and effects of silver transferred by the diet in zebrafish, brine shrimp larvae were exposed to 100 ng L-1 of Ag NPs as an environmentally relevant concentration or to 100 μg L-1 as a potentially effective concentration and used to feed zebrafish for 21 days. Autometallography revealed a dose- and time-dependent metal accumulation in the intestine and in the liver of zebrafish. Three-day feeding with brine shrimps exposed to 100 ng L-1 of Ag NPs was enough to impair fish health as reflected by the significant reduction of lysosomal membrane stability and the presence of vacuolization and necrosis in the liver. However, dietary exposure to 100 μg L-1 of Ag NPs for 3 days did not significantly alter gene transcription levels, neither in the liver nor in the intestine. After 21 days, biological processes such as lipid transport and localization, cellular response to chemical stimulus and response to xenobiotic stimulus were significantly altered in the liver. Overall, these results indicate an effective dietary transfer of silver and point out to liver as the main target organ for Ag NP toxicity in zebrafish after dietary exposure.MINECO (NanoSilverOmicsproject- MAT2012-39372) Basque Government (consolidated research groups IT810-13 and IT620-13; Saiotek S-PE13UN142) University of the Basque Country (UFIs 11/37 and 11/52)

Experimental evidence of a cluster-glass transition on the colossal magnetoresistance manganite La0.7Pb0.3(Mn0.9Fe0.1)O3

4 págs.; 3 figs. ; PACS numberssd: 75.40.2s, 75.47.2m, 61.12.Ex, 61.46.1wNeutron small angle scattering on a colossal magnetoresistance material shows clear signatures of a rise in characteristic length of paramagnetic fluctuations as the maximum of dc susceptibility is approached from high temperatures. The phenomenon is accompanied by a rise in intensity of a broad peak that appears at wave vectors of ≈ 0.025-1, and this is interpreted as a fingerprint of the onset of ferromagnetic ordering due to intercluster magnetic interactions. © 2005 The American Physical Society.Peer Reviewe