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Ane Maider Altuna Zugasti

Publicaciones científicas más recientes (desde 2010)

Autores: López-Arancibia, Aitziber; Aldasoro, H.; et al.
Revista: STRUCTURAL ENGINEERING AND MECHANICS
ISSN 1225-4568  Vol. 56  Nº 3  2015  págs. 355 - 367
This paper deals with a new designed joint system for single-layer spatial structures. As the stability of these structures is greatly influenced by the joint behaviour, the aim of this paper is the characterization of the joint response in bending through Finite Element Method (FEM) analysis using ABAQUS. The behaviour of the joints studied here was influenced by many geometrical factors, such as bolts and plate sizes, distance between bolts and end-plate thickness. The study comprised five models of joints with different values of those parameters. The numerical results were compared to the results of previous experimental tests and the agreement was good enough. The differences between the numerical and experimental initial stiffness are attributed to the simplifications introduced when modelling the bolt threads as well as the presence of residual stresses in the test specimens.
Autores: Iza, Amaia; Gutiérrez, Isabel;
Revista: METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
ISSN 1073-5623  Vol. 43A  Nº 12  2012  págs. 4571 - 4586
Often, Nb contributes to the strength of a microalloyed steel beyond the expected level because of the grain size strengthening resulting from thermomechanical processing. Two different mechanisms are behind this phenomenon, and both of them have to do with the amount of Nb remaining in solution after hot rolling. The first of them is the increase of the hardenability of the steel as a result of Nb, and the second one is the fine precipitation of NbC in ferrite. Three Nb microalloyed steels were thermomechanically processed in the laboratory and coiled at different temperatures to investigate the effect of Nb content on the tensile properties. The extra strength was linearly related to the Nb remaining in solution after the hot working. The maximum contribution from Nb was reached for a coiling temperature of 873 K (600 A degrees C).
Autores: Aizpurua, H.; López-Arancibia, Aitziber;
Revista: THE IES JOURNAL. PART A: CIVIL & STRUCTURAL ENGINEERING
ISSN 1937-3260  Vol. 5  Nº 4  2012  págs. 263 - 268
The necessity to offer differentiated solutions for architectural projects is fostering the development of single-layer spatial structures. As the stability of these structures largely depends on the stiffness of the joints, new joint designs have to be sought. The authors performed various experimental tests on a new kind of joint for tubular members of single-layer structures in order to evaluate the joint stiffness. The aim of the study is to find a finite element model to reproduce the experimental responses, so that the behaviour of the joint can be predicted without the need for further experimentation. The proposed models mainly differed in the way the bolt connection was simulated, as bolts were the most complex elements. The paper presents the comparison between experimental results and numerical results obtained from the different finite element models developed for the joints. One of the three models provided good results even though it was simple.
Autores: López-Arancibia, Aitziber; Puente, Iñigo;
Revista: JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH
ISSN 0143-974X  Vol. 72  2012  págs. 219 - 226
Although there is a great deal of papers on single-layer latticed structures, practically the totality of them is devoted to domes. Therefore, the authors have chosen to analyse squared plan-form single-layer structures studying the influence of joint-rigidity, mesh-density, rise-to-span ratio and load combination in their behaviour, through a Design of Experiments analysis. After identifying the most influential parameters, more FEM analyses were run resulting in interesting conclusions which included economic considerations. The influence of initial imperfections was also investigated. (C) 2011 Elsevier Ltd. All rights reserved.
Autores: Iza, Amaia; et al.
Revista: METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
ISSN 1073-5623  Vol. 43A  Nº 12  2012  págs. 4553 - 4570
While the role of Nb during the processing of austenite is quite clear, what happens in subsequent stages to the concentration of this element left in solution is subject to some debate. In particular, some uncertainty still subsists concerning the eventual homogeneous precipitation in Nb supersaturated polygonal ferrite. The present work was aimed at clarifying the precipitation sequence of Nb during coiling, through a systematic work and a careful selection of the processing conditions in order to produce different scenarios concerning the initial state of Nb. A Nb-microalloyed steel was thermomechanically processed in the laboratory followed by simulated coiling at different temperatures in the 873 K to 1023 K (600 A degrees C to 750 A degrees C) range. Transmission electron microscopy (TEM) showed interphase precipitation of NbC at high coiling temperatures, while at 873 K (600 A degrees C), homogeneous general precipitation took place in ferrite and followed a Baker-Nutting orientation relationship.

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