Torsion and its interaction with other internal forces in EN 1993-1-1: a new approach

This is the accepted version of the following article: [Real, E., Bordallo, J. and Real, E. (2016), Torsion and its interaction with other internal forces in EN 1993-1-1 – a new approach. Steel Construction, 9: 240–248. doi:10.1002/stco.201500005], which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/stco.201500005/abstractThis paper presents and clarifies the treatments included in EN 1993-1-1, relating to checking the resistance of the steel cross-sections under torsion and its interaction with other internal forces. Specifically, the origin of the formulations for shear-torsion interaction, which was not found in the literature, is presented. Furthermore, a very simple formulation based on the expressions used for shear-torsion interaction is developed, in order to take into account bending-warping torsion interaction for symmetrical double T cross-sections (IP and HE steel profiles). Such formulation overcomes the overly conservative approach stated in EN 1993-1-1, for Class 1 and Class 2 cross-sections (plastic and compact cross-sections). Finally, a rigorous method for the determination of the bending resistance of cross-sections is proposed, considering the interaction with shear and torsion. The proposal is well suited to the concept of cross-sectional class and it is perfectly consistent with the approaches set out to consider the bending-shear and bending-warping torsion interactions.Peer ReviewedPostprint (author's final draft

Comportamiento estructural de puentes tipo network con arcos inclinados

The paper describes a broad parametric study of the structural behaviour of network arch bridges with laterally inclined and parallel arches under vertical and lateral loading. Influence of the angle of arches, upper bracing type, f/L arch ratio, number and angle between the hangers on structural behaviour of the bridge members is investigated. Five separate studies are conducted using precise three-dimensional models with tubular arch profiles combined with orthotropic steel deck. Traffic and lateral wind load models include uneven loading across the width and length of the deck. Design recommendations based on the analysis of results concerning optimum values of each investigated parameter are presented.Postprint (published version

Criterios de diseño en puentes de hormigón frente a la acción térmica ambiental

El presente trabajo centra su estudio en la problemática de los efectos térmicos ambientales en puentes de hormigón. Los objetivos perseguidos en esta tesis son, por una parte, el desarrollo de un modelo analítico capaz de obtener la respuesta térmica y tensional a nivel sección de los tableros de puentes de hormigón y el estudio de la influencia de todos los parámetros que intervienen en el fenómeno de la transmisión del calor en esta tipología estructural. Por otra parte, se presenta una metodología general de obtención de las acciones térmicas y los estados tensionales asociados, a considerar en el proceso de análisis y diseño de los puentes de hormigón. Dicha metodología ha sido aplicada, con posterioridad, al caso de puentes de hormigón emplazados en la geografía de nuestro país, siendo las bases de datos los resultados de los amplios estudios paramétricos llevados a cabo para cada una de las tipologías transversales de tablero comúnmente adoptadas en proyecto, y la información climatológica y ambiental recogida en las publicaciones del Instituto Nacional de Meteorología.The present work is based on the problem of environmental thermal effects on concrete bridges. In this study, an analytical model is developed to determine the time-dependent temperature distributions and the self-equilibrated longitudinal and transversal stresses distributions within the cross section of concrete bridges. Parametric studies are carried out in order to find the effects of all parameters governing the heat transfer and conduction problem. Moreover, a general methodology in order to obtain design stresses distributions and design thermal loads is presented. Such methodology is applied to the case of concrete bridges in Spain. Data bases are the results of parametric studies and the environmental information presented in several reports of National Institute of Meteorology

Modelo de obtención de distribuciones de temperaturas y de tensiones longitudinales autoequilibradas en puentes de hormigón

El interCs por la problemática de los efectos tCrmicos en las estructuras de hormigón y, en particular, en los puentes de hormigón ha ido aumentando notablemente en los últimos años. En este artículo se presenta un modelo de obtención de distribuciones de temperaturas y de tensiones longitudinales autoequilibradas en puentes de hormigón basado en un esquema bidimensional en diferencias finitas correspondiente al método explícito de resolución de ecuaciones diferenciales en derivadas parciales. Los resultados obtenidos mediante la aplicación del presente modelo se comparan con resultados experimentales y analfticos obtenidos por otros autores apreciándose una gran bondad en el ajuste. El programa numirico desarrollado se muestra como una útil herramienta de cara a su aplicación al análisis y diseño de puentes de hormigón -puentes losa, puentes cajón y puentes de vigas- frente a los efectos térmicos ambientales.During the last years, the interest in the study of thermal effects on concrete bridges has increased considerably. In this paper, an analytical model based on two-dimensional finite difference method is described to determine the time-dependent temperature distributions antl the self-equilibrated longitudinal stresses distributions within the cross section of concrete bridges. The results derived from the present method are compared with experimental and analytical results obtained by other authors, exhibiting a general good agreement. The numerical program developed has shown to be an useful tool for the analysis and design of concrete bridges in front of environmental thermal effects.Peer Reviewe

Numerical study on stainless steel I-shaped links on eccentrically braced frames

Strength, ductility and strain-hardening on austenitic stainless steel are interesting structural properties that suggest a potential strategic structural application as dissipative members in seismic-resistant systems. Eccentrically braced frames (EBF) are structural systems that dissipate energy during seismic episode by means of shear- or bending-shear related mechanisms in particular elements commonly referred to as links. The use of austenitic stainless steel in these links may represent an interesting alternative for EBF. As a strategic solution aimed at exploiting the stainless steel structural properties, non-dissipative zones may be assembled with carbon steel whereas dissipative zones may be assembled with austenitic stainless steel. This paper presents a numerical study on austenitic stainless steel, I-shaped, short links on EBF subjected to cyclic loading. The study encompasses a set of parametric analysis in which the web slenderness, transverse stiffening and material properties of the elements are systematically varied. Strain-hardening, energy dissipation and residual displacement are evaluated for stainless steel links and the carbon steel counterparts. The results suggest that austenitic stainless steel links may provide to the EBF system an interesting solution that enhances their overall behaviour during energy dissipation-related episodes.Peer ReviewedPostprint (author's final draft

Influence of the degree of utilization on the structural behaviour of stainless steel frames subject to fire

Stainless steel is known to have a better behaviour at elevated temperatures than carbon steel. This, combined with its aesthetic appeal and corrosion resistance, makes stainless steel structures an attractive alternative to carbon steel structures. However, EN 1993-1-4 does not establish de-sign rules associated with global analysis of stainless steel frames and EN 1993-1-2, devoted to carbon steel, provides a conservative approach for the fire design of stainless steel structures. Hence, current European codes do not provide efficient design guidelines for stainless steel frames subject to fire and therefore the response of this type of structures should be assessed by means of experimental tests and/or numerical analyses. The main objective of the paper is to assess the nonlinear structural response of stainless steel frames subjected to fire, focusing the investigation on the influence of the degree of utilization. A comprehensive numerical analysis on Class 1 and Class 3 stainless steel frames and Class 1 carbon steel frame subjected to fire is carried out varying the degree of utilization. Calibration of the FE models has been carried out as a part of a study of transient thermo-mechanical models, which are needed to assess the response of stainless steel frames subjected to fire.The authors acknowledge the funding from the MINECO (Spain) un-der Project BIA2016-75678-R, AEI/FEDER, UE “Comportamiento estructural de pórticos de acero inoxidable. Seguridad frente a ac-ciones accidentales de sismo y fuego”.Peer ReviewedPostprint (author's final draft

Resistance of hybrid steel plate girders subjected to patch loading

Hybrid girders have proven to be an economical alternative to homogeneous girders since they provide a greater flexural capacity. One of the potential applications of hybrid steel plate girders is their usage in bridge construction. One of the potential constructive methods of these bridges is the push launch method, in which patch loads may condition the design. The aim of this paper is to present advanced conclusions of a research work dealing simultaneously with these two fields; the hybrid typology when subjected to the particular case of patch loading. The most remarkable results of the research work are pointed out. On the one hand, it is shown that the influence of the fyf/fyw ratio (namely, the hybrid grade) is negligible for girders with largely spaced transverse stiffeners. On the other hand, it is shown that this influence can be significant if the transverse stiffeners are closely spaced. Suggestions for considering these findings on design codes are provided at the end paper.Peer ReviewedPostprint (published version

Transversally and longitudinally stiffened steel plate girders subjected to patch loading

This article presents some observations related to the phenomenon that occurs when transversally and longitudinally stiffened steel plate girders are subjected to patch loading. The failure mechanism differs considerably for the particular structural case of girders with largely spaced transverse stiffeners, which have been studied thoroughly in last decades. Steel plate girders with closely spaced stiffeners are occasionally found in bridge design and for such cases, the current EN1993-1-5 rules underestimate the strength of the webs to transverse forces. Research work on girders with closely spaced transverse stiffeners is available but for such cases, the web plates are longitudinally unstiffened. Some comparisons between the results obtained and those provided by EN1993-1-5 are discussed. Preliminary results suggest that the resistance of densely stiffened steel girders (both transversally and longitudinally) must be studied and subsequently revised accordingly. In addition, it is pointed out that a certain degree of imperfection sensitivity is inferred from the results. Further studies on this topic are necessary.Peer ReviewedPostprint (author's final draft

A model for the analysis of concrete dams due to environmental thermal effects

This author accepted manuscript is deposited under a Creative Commons Attribution Non-commercial 4.0 International (CC BY-NC) licence. This means that anyone may distribute, adapt, and build upon the work for non-commercial purposes, subject to full attribution. If you wish to use this manuscript for commercial purposes, please contact [email protected] this article, an analytical model is presented for the simulation of the thermal behaviour of dams that are subjected to environmental thermal action during service. The method of solution adopted, as well as the evaluation of the different parameters, is described in detail. Also, the theoretical results that are predicted by the model are compared with experimental results obtained through the monitoring of temperature in several dams in Spain. The dams considered are currently in use, of different types and in distinct locations.Peer ReviewedPostprint (author's final draft

On the shear resistance of ferritic stainless steel composite slabs

Steel-concrete composite floors are commonly used in construction due to their favourable weight-to-depth ratio and erection time. Typically, concrete is poured onto a galvanised steel deck acting as formwork. However in case of floors exposed to corrosive environments, stainless steel is likely to be chosen over galvanised steel. Besides its better corrosion resistance, stainless steel also offers desirable aesthetic appearance and good mechanical properties. Composite slabs can fail in bending, vertical shear or longitudinal shear. The latter failure mode is the most common, and its prediction depends on values obtained through full-scale tests. However, for stainless steel decks, no specific treatment exists in current design standards. This paper investigates the longitudinal shear resistance of stainless steel composite slabs through an experimental study. One short and three long span slabs, made using a Cofraplus 60 ferritic EN1.4003 stainless steel corrugated deck, are tested in accordance with Eurocode 4, annex B.3 [1]. The Partial Shear Connection (PSC) method is used to assess the longitudinal shear resistance. The experimental results, together with the results provided in Task 3.3 of the “Structural Applications of Ferritic Stainless Steels (SAFSS, RFSR-CT-2010-00026)” project [2], are used to draw conclusions on the applicability of ferritic stainless steel decks in composite floors.Peer ReviewedPostprint (author's final draft