Nuestros investigadores

Aitziber López de Arancibia

Publicaciones científicas más recientes (desde 2010)

Autores: Markel Alaña, (Autor de correspondencia); López-Arancibia, Aitziber; Pradera, Ainara; et al.
Revista: JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS
ISSN 1751-6161  Vol. 98  2019  págs. 357 - 368
As result of the advances made in additive manufacturing in recent years, the design of porous materials with controlled mechanical properties has gained importance due to their capability to offer case-specific solutions in multiple applications. In terms of biomaterials, the use of lattice structures provides a considerable variety of mechanical and geometric properties that can enhance osseointegration and reduce stress shielding. In this paper, the elastic response of a modified face-centered cubic (FCC) unit cell was studied, and analytical expressions for macroscopic effective Young's moduli, shear moduli and Poisson's ratios were obtained, thus providing the necessary parameters for the homogenization of the unit cell. The analytical expressions of the homogenization parameters open the possibility for implementation in other research fields, such as topology optimization. Timoshenko beam theory was used to model the struts of the modified FCC unit cell and a finite element analysis using shear flexible beam elements was performed to assess the accuracy of the analytical expressions. In addition to modelling the bending of the beams, axial and torsional displacements were also considered for a more detailed analysis. It can be concluded that the expressions obtained represent the elastic behavior of the modified FCC unit cell with high accuracy.
Autores: Pradera, Ainara; López-Arancibia, Aitziber; et al.
Revista: INTERNATIONAL JOURNAL OF ENGINEERING EDUCATION
ISSN 0949-149X  Vol. 31  Nº 5  2015  págs. 1299 - 1308
This paper presents what we call the Multiple Approach Experimental Project (MAEP), a project based on the model-building approach to learning. The MAEP complements theoretical lectures by placing students in a real situation where they design and build a physical structure. A total of 65 students divided into 24 teams voluntarily took part in the competition. Assessments from students who participated in the MAEP along with assessments from the instructors who implemented it are presented. Results show that the MAEP was welcomed and that the objective of engaging students in the subject was met.
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: 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: Serna, Miguel Ángel; Ibanez, J.; López-Arancibia, Aitziber;
Revista: JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH
ISSN 0143-974X  Vol. 67  Nº 7  2011  págs. 1078 - 1085
Experienced structural engineers have an intuitive understanding of the buckling behavior of uniform members subjected to compressive loads. The Euler critical load and the concept of buckling length are extensively used in this context. Unfortunately, the extension of this intuitive approach to cases with non-uniform load or non-uniform members is not straightforward. Based on an extensive numerical parametric study, the paper first presents a closed-form expression for the buckling load of constant cross-section members with non-uniform axial loading. Consequently, an equivalent load approach for non-uniform members subjected to non-uniform axial load distribution is proposed and validated. The combination of both procedures has the power of transforming the general complex case of a non-uniform member under non-uniform load into an equivalent simple case of a uniform member subjected to uniform load. The new methodology is simple and direct, and produces more than acceptable approximate results. (C) 2011 Elsevier Ltd. All rights reserved.
Autores: López-Arancibia, Aitziber; Puente, Iñigo; Aizpurua, H.;
Revista: ENGINEERING STRUCTURES
ISSN 0141-0296  Vol. 33  Nº 3  2011  págs. 731 - 737
In the design of single-layer structures, the hypothesis of pinned joints leads to structures with low capacity in terms of stability and resistance. Therefore, one of the main concerns of structural designers in recent years has been to find an appropriate joint design which would endow the joint with sufficient stiffness. In this paper, the results of experimental tests conducted with the aim of establishing geometrical parameters for a semi-rigid joint that may be used in single-layer structures are presented. They showed how the combination of different parameters can improve the stiffness of the joint and its rotational capacity. At the same time, the experimental tests provided the initial rotational stiffness of the tested joints which is to be introduced into the analysis of the structure. The paper presents an analytical method for the determination of the initial rotational stiffness of the joint. The method follows a technique similar to the component method of Eurocode 3 part 1.8, although it has been adapted to the geometry of this particular joint. (C) 2010 Elsevier Ltd. All rights reserved.
Autores: Yong, D.J.; López-Arancibia, Aitziber; Serna, Miguel Ángel;
Revista: INTERNATIONAL JOURNAL OF STRUCTURAL STABILITY AND DYNAMICS
ISSN 0219-4554  Vol. 11  Nº 2  2011  págs. 345 - 361
The paper presents a comparative study of a well-established steelwork design standard, the American AISC LRFD, and the new European code for the design of steel structures, Eurocode 3. The study is focused on the resistance capacity of steel members subjected to one of the following load cases: axial compression, bending, and combined axial compression and bending. First, the paper compares the formulation of both codes in order to identify similarities and differences. Particular attention is given to the resistance of beam columns since many steel structural members in building structures fall into this category. In the case of pure bending and combined axial compression and bending, the paper considers two extreme cases of linear moment distribution: equal end moments and opposite end moments. The results are presented graphically in order to make possible their interpretation and to detect significant differences in resistance. The comparative study shows that the resistance capacities given by LRFD and EC3 can differ appreciably for some of the cases considered. Moreover, there are also significant differences between the two methods proposed by the Eurocode when slenderness is high and the beam is subjected to linear moment distribution with opposite end moments. Finally, the paper stresses those points where each standard offers a simpler approach.
Autores: Santilli, Adrián; Puente, Iñigo; López-Arancibia, Aitziber;
Revista: CONSTRUCTION AND BUILDING MATERIALS
ISSN 0950-0618  Vol. 25  Nº 1  2011  págs. 227 - 238
An analysis of experimental models for predicting fresh concrete lateral pressure in walls and bases was carried out, including a comparison of three rate of placements. Experimental data obtained from the bibliography were used for comparing the adequacy of the models, making a division into three placement rates ranges: under 2 m/h, between 2 m/h and 10 m/h and over 10 m/h. The comparisons were established not only in the different ranges but also taking into account the level of construction control, vigilance and inspection, considering in all cases safety and adequacy for better formwork design. The influence of concrete yield stress, evaluated from slump test, is also analyzed; the study shows a low correlation between concrete yield stress and the ratio maximum pressure vs. hydrostatic pressure for low rates of placement. On the other hand for higher rates of placement, the correlation increases. (C) 2010 Elsevier Ltd. All rights reserved.
Autores: Santilli, Adrián; Puente, Iñigo; López-Arancibia, Aitziber;
Revista: CONSTRUCTION AND BUILDING MATERIALS
ISSN 0950-0618  Vol. 24  Nº 6  2010  págs. 934 - 945
An analysis of experimental models for predicting fresh concrete lateral pressure in columns was carried, raising the issue of a fundamental parameter like the rate of placement. Experimental data obtained from different authors were utilised for comparing the adequacy of the different theories making a division into three zones: rates of placement under 3 m/h, between 3 m/h and 10 m/h and over 10 m/h. The results were established not only in the different zones but also taking into account safety and adequacy. To determine the most suitable model according to rate of placement, level of control, vigilance, planning and inspection of the construction, eight models proposed under different standards or by different authors were compared with respect to the hydrostatic pressure produced by a liquid with concrete density. The influence of concrete yield stress, evaluated from slump test is also analyzed; the study shows a low correlation between concrete yield stress and the maximum pressure vs. hydrostatic pressure ratio. (c) 2009 Elsevier Ltd. All rights reserved.
Autores: Puente, Iñigo; Santilli, Adrián; López-Arancibia, Aitziber;
Revista: ENGINEERING STRUCTURES
ISSN 0141-0296  Vol. 32  Nº 1  2010  págs. 195 - 206
The design of vertical formwork is dependent on the lateral pressure predicted to act on the form face. Experimental research into the construction of blocks on a gravity dam was carried out with the objective of verifying and comparing the adequacy of different theories. Pressure was measured indirectly as the load on the trusses of formwork support, which allows verification of the adequacy of the integral of the pressure envelopes, proposed by different authors, using a finite element model in ABAQUS. An analysis of the relationship between safety and exactitude was carried out with the objective of determining which method apply to formwork design depending on: safety factors, work monitoring, degree of planning and knowledge about the filling process. It was concluded by recommending the application of different theories based on these parameter values. (C) 2009 Elsevier Ltd. All rights reserved.