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The in-house credit assessment systems (ICASs) developed by euro area national central banks (NCBs) are an important source of credit risk assessment within the Eurosystem collateral framework. They allow counterparties to mobilise as collateral the loans (credit claims) granted to non-financial corporations (NFCs). In this way, ICASs increase the usability of non-marketable credit claims that are normally not accepted as collateral in private market repo transactions, especially for small and medium-sized banks that lend primarily to small and medium-sized enterprises (SMEs). This ultimately leads not only to a widened collateral base and an improved transmission mechanism of monetary policy, but also to a lower reliance on external sources of credit risk assessment such as rating agencies. The importance of ICASs is exemplified by the collateral easing measures adopted in April 2020 in response to the coronavirus (COVID-19) crisis. The measures supported the greater use of credit claim collateral and, indirectly, increased the prevalence of ICASs as a source of collateral assessment. This paper analyses in detail the role of ICASs in the context of the Eurosystem's credit operations, describing the relevant Eurosystem guidelines and requirements in terms of, among other factors, the estimation of default probabilities, the role of statistical models versus expert analysis, input data, validation analysis and performance monitoring. It then presents the main features of each of the ICASs currently accepted by the Eurosystem as credit assessment systems, highlighting similarities and differences.

International audience; This work presents the finite element analysis of partially stiffened cylinders subjected to axial compression at elevated temperatures. The compressive strength is calculated for self-weight conditions and the influence of the temperature on the material response is also investigated. In the oil industry, pressure vessels are commonly used operating at complex design conditions such as high-pressure profiles and/or elevated temperature gradients which affect considerably the structural response of inner components. Among them, risers become sensitive steel elements withstanding heavy compressive loading due to self-weight, as well as, insulation elements added to protect them from the elevated temperature gradient. Most risers structurally fail at the bottom end due to buckling caused by self-weight and temperature effects. To remediate this situation and to guarantee the integrity of the riser, longitudinal stiffeners are welded at the bottom end. Hence, a proper determination of the compressive strength of the cylinder, taking into account the influence of the longitudinal stiffening and the corresponding temperature, is required. Results indicate that the use of longitudinal stiffeners in deformed cylinders increases the strength to buckling in percentages that vary according to the cross-section of the profiles.; Este trabajo presenta el análisis de elementos finitos de cilindros parcialmente rígidos sometidos a compresión axial a temperaturas elevadas. La resistencia a la compresión se calcula para las condiciones de peso propio y también se investiga la influencia de la temperatura en la respuesta del material. En la industria del petróleo, los recipientes a presión se utilizan comúnmente para operar en condiciones de diseño complejas, como perfiles de alta presión y/o gradientes de temperatura elevados que afectan considerablemente la respuesta estructural de los componentes internos. Entre ellos, los raisers se convierten en elementos de acero sensibles que soportan una carga alta de compresión debido al peso propio, así como, elementos de aislamiento agregados para protegerlos del gradiente de temperatura elevada. La mayoría de los raisers fallan estructuralmente en el extremo inferior debido a la deformación causada por el peso propio y los efectos de temperatura. Para remediar esta situación y garantizar la integridad de la tubería vertical, los refuerzos longitudinales están soldados en el extremo inferior. Por lo tanto, se requiere una evaluación adecuada de la resistencia a la compresión del cilindro, teniendo en cuenta la influencia del refuerzo 132 E. longitudinal y la temperatura correspondiente. Los resultados indican que el uso de refuerzos longitudinales en cilindros deformados aumenta la resistencia al pandeo en porcentajes que varían de acuerdo con la sección transversal de los perfiles.

Currently, one of the most used steel bridge assembly methods is the Incremental Launching Method (ILM). Its practical application consists in passing the bridge assembly through a launching shoe as well as over each support pile. For steel plate girders, a concentrate vertical reaction also known as patch loading is generated over one the flanges when ILM is employed, and depending on the geometrical and material properties of the girder, buckling failure in the web panel may occur. To overcome this type of failure, plate girders are reinforced with longitudinal stiffeners. Therefore, this paper aims at investigating the effect of the bearing length on the elastic buckling behavior of longitudinally stiffened girder webs subjected to patch loading. Buckling coefficients of longitudinally stiffened girder webs are calculated by means of linear finite element analysis. Furthermore, a parametric analysis is performed to study the influence of other geometric parameters such as the panel aspect ratio and the geometrical properties of the longitudinal stiffener on the buckling coefficient. The results show that for longitudinally stiffened girder webs the buckling coefficient increases with the loading length. However, this conclusion is considerably affected by other factors such as the position of the stiffener, and panel aspect ratios. RESUMEN Uno de los métodos de ensamblaje de puentes de acero más utilizados en la actualidad es el Método de Lanzamiento por Empujes Sucesivos, también abreviado como ILM por sus siglas en ingles. Su aplicación práctica consiste en pasar el ensamblaje de puentes a través de las zapatas de lanzamiento, así como sobre cada pila de soporte. Para vigas de acero se genera una reacción vertical de carga concentrada sobre una de las aletas cuando se emplea ILM, y dependiendo de las propiedades geométricas y de material de la viga esto puede ocasionar una falla de pandeo localizado sobre el alma. Para evitar este tipo de fallas, las vigas son reforzadas con rigidizadores longitudinales. Muchas investigaciones han estudiado la influencia de diferentes parámetros geométricos sobre el comportamiento de pandeo elástico de vigas sujetas a carga concentrada, sin embargo, el efecto de la longitud de apoyo ha recibido poca atención. Este artículo se enfoca en investigar la influencia de la longitud de apoyo en el comportamiento de pandeo elástico de vigas esbeltas con rigidización longitudinal sujetas a carga concentrada. El coeficiente de pandeo de las vigas esbeltas rigidizadas longitudinalmente fue calculado por medio análisis lineal por elementos finitos. Para ello se realizó un estudio paramétrico con el propósito de evaluar la influencia de otras variables adicionales como la relación de aspecto del panel y las propiedades geométricas de los rigidizadores sobre el coeficiente de pandeo. Los resultados muestran que para una viga rigidizada longitudinalmente el coeficiente de pandeo incrementa con la longitud de carga. Sin embargo, este incremento se ve considerablemente afectado por otros factores tales como la posición del rigidizador y la relación de aspecto del panel.

In the construction of traditional composite bridges whose structure consists of plate girders, the concrete slabs of the decks are often casted before launching. These thin-walled webs are occasionally reinforced with longitudinal stiffeners to increase bending and shear strengths, and for bridges erected by incremental launching, these stiffeners also provide an enhancement for patch loading resistance. Experimental works have shown that ultimate resistance to patch loading is highly dependent on the size, relative position and shape of the longitudinal stiffener. Nonetheless, a comparison between those three factors should be carried out in order to establish the optimum configuration of longitudinal stiffening for webs under compressive forces. Hence, this study attempts to compare the increase of ultimate strength of a slender I-girder subjected to concentrated load using open and closed section types of stiffeners, evaluating three different stiffeners configurations: i) a single open section stiffener, ii) multiple open section stiffeners, and iii) a single closed section stiffener. The nonlinear computations were performed using a finite element analysis parametric model, where the relative position and size of the stiffeners are varied to cover a wide range of geometries.

Incremental launching is one of the common steel bridge assembly methods used nowadays, its practical application consists in passing the bridge assembly through the launching shoes as well as over each support pile. In some cases, when plate girders are used, it is usual to find longitudinal stiffeners reinforcement in order to prevent web local buckling produced by the vertical reaction acting in the support pile. A considerable number of studies have focused on evaluating the impact of a single stiffener on the resistance of plate girder subjected to patch loading. However, the effect of multiple longitudinal stiffened plate girders subjected to lengthy compressive load has received little attention. Therefore, this paper aims at studying the influence of load bearing length on the ultimate strength of multiple longitudinally stiffened webs subjected to compressive loads. Patch loading resistance is numerically calculated using a previously validated nonlinear finite element analysis. Subsequently, a parametrical study is conducted to investigate the effect of the aforementioned load length and the relative position and size of the stiffeners on the ultimate strength

This paper is aimed at studying the elastoplastic behavior of longitudinally stiffened girder webs subjected to patch loading and bending. The investigation is carried out by means of nonlinear finite element analysis to study the structural behavior of the girder components (flanges, web and stiffener) at ultimate limit state. Initial geometrical imperfections, plastic material behavior and large deflection effects are considered in the model. For the numerical model validation, the computer results from the simulations are compared with experimental results taken from the literature. A parametric study was carried out in order to investigate the influence of the applied bending moment and the relative location of the stiffener on the ultimate strength to patch loading. Este artículo está enfocado en estudiar el comportamiento elastoplástico de vigas rigidizadas longitudinalmente en el alma y sujetas a combinaciones de carga concentrada y momento flector. La investigación se realiza mediante un análisis de elementos finitos no lineal para estudiar el comportamiento estructural de los diferentes componentes de la viga (aletas, alma y rigidizador) bajo el estado límite de carga. El modelo considera los efectos de imperfecciones geométricas iniciales, comportamiento plástico del material y grandes deflexiones. La validación del modelo numérico se hace mediante comparación directa de los resultados numéricos con valores experimentales disponibles en la literatura técnica. Finalmente, se realiza un estudio paramétrico con el objeto de investigar la influencia del momento flector y la localización del rigidizador en la resistencia última de la viga bajo cargas concentradas.

Longitudinally stiffened I-girders are commonly used to build incrementally launched steel bridges. During the bridge launching, the girders are subjected to concentrated loading at the support points. These loads are generally larger than those the structure would sustain once located in its final operating position. Numerical studies have considered girder segments subjected to concentrated loading where the boundaries are simulated by kinematic constraints. It represents rigid body conditions where elements at the supported end are allowed only to rotate about an axis perpendicular to the girder web. The load is applied on the girder flange along a small length compared to the total width of the evaluated segment. This paper is aimed at investigating the validity of this hypothesis for longer lengths of the applied load. Herein, the ultimate load of a stiffened girder is determined through finite element modeling, considering the boundaries conditions in two different ways: (1) considering kinematic constraints; and (2) simulating a transverse stiffener. In addition, the used model considers the plastic behavior of the material, the existence of imperfections in the web of the girder and the effects of large deformations. The results show that for short length loadings both hypotheses yield similar results. However, as the loading length increases, significant differences in the results are observed. En la actualidad se utilizan vigas rigidizadas longitudinalmente en el lanzamiento de puentes mediante el método de voladizos sucesivos. Durante el lanzamiento las vigas son sometidas a cargas concentradas en los puntos de apoyo. Estas cargas son generalmente mayores a aquellas que soportaría la estructura una vez ubicada en su posición final de funcionamiento. En estudios numéricos se han analizado segmentos de vigas sometidos a cargas concentradas cuyos extremos son modelados considerando restricciones cinemáticas que simulan condiciones de cuerpo rígido. Los elementos en los bordes de la estructura son restringidos cinemáticamente permitiendo sólo la rotación con respecto a un eje perpendicular al alma de la viga. La carga se aplica sobre el ala de la viga a lo largo de una pequeña longitud en comparación con el ancho total del segmento bajo estudio. El objetivo de este trabajo es verificar la validez de dicha hipótesis para grandes longitudes de carga aplicada. La carga última de la viga rigidizada se determina mediante un análisis por elementos finitos modelando los extremos de la viga de dos maneras: (1) considerando restricciones cinemáticas, y (2) simulando un rigidizador transversal. El modelo también considera el comportamiento plástico del material, la existencia de imperfecciones en el alma de la viga y los efectos de grandes deformaciones. Los resultados muestran que para cargas aplicadas sobre longitudes cortas ambas hipótesis arrojan resultados similares, sin embargo al aumentar la longitud de carga ambos resultados divergen.