Luis Augusto Godoy

National University of Cordoba, Argentina | UNC · Institute for Advanced Research in Engineering and Technology

This paper presents a qualitative description of structural damage in aboveground steel tanks in oil refineries and facilities, which were observed during reconnaissance missions to the states of Texas and Louisiana following Hurricanes Katrina and Rita in 2005. Qualitative evidence of damage is shown using photographs taken during the reconnaissan...

The identification of the origins of what we now call the theory of elastic stability is not an easy task. Most authors trace the origins to the pioneering work of Leonhard Euler in 1744, and some shift this origin to the experimental works of Petrus van Musschenbroek in 1729. However, other contemporary authors interested in the history of the dis...

Oil storage tank farms are complex systems and the eventual failure of one of their components could affect the whole system. A risk assessment requires identifying the magnitude of the damage that can occur under certain load level. Fragility curves for oil storage tanks with a floating roof are obtained in this work, to estimate the probability o...

This paper deals with the dynamic behavior of cylindrical shells under blast loads, with special ref-erence to plasticity and plastic buckling. Interest in this problem focuses on the response of steel vertical oil storage tanks with a flat roof under a nearby explosion. The problem is modeled using a finite element discretization of the structure,...

This chapter reviews the main features involved in the investigation of structural consequences due to fire and explosions affecting tanks in the oil industry. The sources of fire or explosions are considered to be located outside a target tank, whereas internal explosions in tanks are not emphasized here.

This paper presents a new displacement solution based on a Modified Fourier Series (MFS) for isotropic linear elastic solids under plane strain or plane stress states subject to continuous displacement and traction boundary conditions in a two-dimensional rectangular domain. In contrast with existing approaches that are restricted to Fourier series...

This paper presents the analytical formulation and numerical results for a two degree-of-freedom model representing the thermal buckling behavior of vertical storage tanks. The model is an extensible column with a simple support at the base, an elastic spring at the top, and an elastic lateral foundation, subjected to a uniform temperature field. T...

The localized settlement of columns in large metal industrial buildings induces out-of-plane displacements of side walls of the same order as the settlement, which may affect service conditions in the building. For a structural configuration formed by frames, side-walls and wall-girts, this work reports results from testing a small-scale model toge...

The huge economic and environmental consequences due to explosions in the oil industry have motivated the study of thin‐walled cylindrical shells subjected to impulsive waves due to an explosion. This chapter focuses on a simple geometrically nonlinear two degree‐of‐freedom system subjected to impulsive loads of very short duration with respect to...

Exact analytical solutions for the free vibrations of Thin-Walled shallow shells are presented in this work. The shells considered have rectangular planform and two principal constant curvatures. Past treatment of this problem included only one possible case of boundary conditions, and was limited to symmetric modes only. The new solutions address...

This paper reports research on the thermal buckling and post-buckling of vertical steel tanks under heat induced by a nearby burning tank. A two-layer solid flame model is adopted and a heat transfer analysis is carried out to compute temperatures in the target tank. The temperatures are used as input in the structural analysis based on a geometric...

The static and dynamic behavior of a horizontal cylindrical shell (as used to store fuels in tanks) is investigated in this work by means of computational modeling. Under a distributed pressure commonly used to model effects due to explosions, the geometrically nonlinear behavior is explored to identify bifurcation and limit points along the static...

This paper concentrates on the work by Petrus van Musschenbroek published in 1729, constituting apparently the first study in the literature on column buckling. To understand the significance of the Musschenbroek's contribution we provide the combined personal, historic and scientific contexts in which he carried out his studies; he was the first r...

The analytical approach of Leonhard Euler to the solution of an elastic column under compression is seen today as a landmark in buckling studies. However, this work was not well received in Great Britain during the late XVIII and XIX centuries. This paper considers the reaction of John Robison, Professor at the University of Edinburgh, published as...

This paper addresses the thermal buckling behavior of tanks having a fixed roof, as employed to store fuel in the oil industry. The study is performed based on finite element analyses of the shell, including linear analysis, linear bifurcation analysis, and geometrically and constitutive nonlinear analysis, in order to elucidate the mechanics of st...

Este trabajo refleja investigaciones desde varias disciplinas de la ingeniería, llevadas a cabo para identificar y evaluar efectos sobre la infraestructura y sobre el medio físico que son causados por desastres naturales y accidentes, en el contexto de la industria del petróleo. Como amenazas se discuten acciones debidas a viento, fuego y explosion...

This work presents numerical modeling and quantitative results of the heat transfer process from a burning tank to an adjacent tank. The flame is represented by a solid flame model in which two zones are identified: a lower clear flame layer with high temperatures and a darker upper layer in which the flame carries soot and smoke. Semi-empirical mo...

In this paper, nine inter-relationships linking the stiffness matrix components of symmetrical or unsymmetrical laminates having transverse matrix cracks in some of the off-axis plies is presented. The crack closure condition under membrane and bending deformations is established and used to obtain the inter-relationships. The derived crack closure...

The relations between the stiffness components of a symmetrical or unsymmetrical laminate having transverse matrix cracks only in the 90-degree laminas are explored in this work. The crack closure condition for these laminates under membrane and bending deformations is established to obtain the interrelationships. These equations also link the in-p...

The nonlinear dynamic response and buckling of a simple, two degree of freedom system is investigated in this work under an impulsive load that simulates a nearby detonation-like explosion. The system includes force and moment springs in much the same way as membrane and bending effects develop in shell structures. The static response is first obta...

The influence of alloy element distributions on austempered ductile iron microstructure and austempering treatment was analysed by a cellular automaton model that considers the ausferritic and martensitic transformations. The initial microstructure is modelled as spherical graphite nodules inserted in an austenitic matrix, in which the alloy elemen...

Austempered ductile iron is frequently employed in the fabrication of automobile parts due to its good mechanical properties, and its sim-plicity and low cost of the manufacturing process. The heat treatment design is an important stage, in which parameters such as tempera-tures and durations are chosen according to the required microstruc-ture, pa...

The development of the ausferritic transformation of a ductile iron was analysed using a novel cellular automaton-finite difference model, which considers geometrical details of the microstructure, nucleation of the new phase at graphite nodule surface, contact between growing phases, and carbon diffusion in austenite. The role of nucleation, auste...

Dimensional variations experienced by materials due to temperature changes are described by the Coefficient of Thermal Expansion (CTE), which is strongly dependent on microstructural features, especially on composites materials. Special attention is given in this work to Spheroidal Graphite Iron (SGI), which is a widespread used metallic alloy, for...

Austempered ductile iron (ADI) is frequently obtained by means of a three-step austempering heat treatment. The parameters of this process play a crucial role on the microstructure of the final product. This paper considers the influence of some process parameters (i.e. the initial microstructure of ductile iron and the thermal cycle) on key featur...

This work addresses the evaluation of the stiffness of fiber-reinforced composite laminates, by means of a computational meso-mechanic model, considering two non-uniformly spaced transverse matrix cracks. Laminates with [0n/908]S and [908/0n]S, with n = 1 and 8, have been studied. The meso-mechanic model includes a three-dimensional Finite Element...

This paper presents a new methodology to evaluate the Cauchy stress tensor at the macro level in computational micromechanics models. The use of control nodes to specify boundary conditions of a Representative Volume Element (RVE) allows deriving equations for the Cauchy stress components, with the consequence that numerical integration in the RVE...

This work reports the modeling and computational implementation of heat transfer processes that take place from a source tank to a target tank in a tank farm, focusing on the thermal field that develops at the target tank. Pool fire with gasoline burning is modeled at the source, in which the flame is represented by a two-layer solid flame model. A...

The three-step austempering heat treatment of ductile iron parts in this paper is simulated by employing a coupled thermo-mechanical-metallurgical model. The thermo-mechanical formulation is solved in the macroscale using the finite element method to predict the evolution of temperatures and deformations in the whole part. The metallurgical model d...

This paper presents a new microstructural model of the stable eutectoid transformation in a spheroidal cast iron. The model takes into account the nucleation and growth of ferrite grains and the growth of graphite spheroids. Different laws are assumed for the growth of both phases during and below the intercritical stable eutectoid. At a microstruc...

This paper presents a new metallurgical model for the ausferritic transformation of ductile cast iron. The model allows predicting the evolution of phases in terms of the chemical composition, austenitization and austempering temperatures, graphite nodule count, and distribution of graphite nodule size. The ferrite evolution is predicted according...

Una de las principales causas de falla estructural en los tanques de almacenamiento de líqui-dos de forma cilíndrica y baja altura se debe a la acción que el viento ejerce sobre ellos. La información de los esfuerzos generados por presiones de viento es de importancia en el diseño y optimización es-tructural de los mismos. La influencia de la forma...

Micro-buckling of unidirectional fiber-reinforced composites is investigated in this paper by means of an explicit representation of a geometrically imperfect fiber within the context of kinematical and material non-linear behavior. Two types of fiber imperfections are considered: a helicoidal shape, identified as 3D imperfection; and a sinusoidal...

This paper presents an analytical solution to predict the nonlinear forced vibrations of elastic thin-walled cylindrical shells under suddenly applied loads. Interest in this problem is motivated by effects due to explosions on fluid-storage metal tanks. The model is based on the energy criterion due to Lagrange, in which the kinematic nonlinear re...

A new model of graphite growth during the continuous cooling of eutectic spheroidal cast iron is presented in this paper. The model considers the nucleation and growth of graphite from pouring to room temperature. The microstructural model of solidification accounts for the eutectic as divorced and graphite growth rate as a function of carbon gradi...

This paper presents a coupled thermo-mechanical-metallurgical formulation to predict the dimensional changes and microstructure of a ductile cast iron part as a consequence of an austempering heat process. To take into account the different complex phenomena which are present in the process, the stress-strain law and plastic evolution equations are...

This paper presents the analysis of mechanical behavior of metal wall panels of storehouses and industrial buildings subjected to differential settlements. The storehouses considered are representative of those used in the agricultural activity. A small-scale model was built and tested in order to have evidence of the behavior and to validate compu...

The strategy of Reduced Stiffness (or Reduced Energy) Analysis, in which selected energy components are eliminated to account for mode interaction and imperfection-sensitivity in a simplified way, was developed by Croll and co-workers since the early 1980s. This physical interpretation allows the formulation as an eigenvalue problem, in which the e...

This work emphasizes novel ways to teach and learn which can be developed by most instructors provided that they have the patience and interest to produce class innovations using computers. The specific approach followed is known as “learning-by-doing in a virtual environment”. The basic idea is to train students to do sophisticated tasks in a way...

La fundición nodular es una aleación metálica de Fe-C-Si cuya microestructura está formada por una matriz, en general compuesta por ferrita y perlita, en la cual se encuentran embebidos nódulos de grafito. Al ser éste un material microscópicamente heterogéneo su comportamiento está definido por las propiedades, morfología y topología de las fases q...

Oil storage tanks are short cylindrical shells fabricated with an external fixed roof or floating roof on the inside. Some features of the structure tend to be simplified in practice and research in order to perform stability and strength analyses using a much simpler model. This paper considers the structural consequences of such simplifications,...

En este trabajo se presenta un analisis del comportamiento estructural de tanques de almacenamiento de petroleo con techo bajo temperaturas procedentes de fuego adyacente a la estructura. En la simulacion numerica se modela la cascara con elementos finitos de doble curvatura utilizando el codigo de propositos generales ABAQUS. Se determinan las con...

En un trabajo anterior sobre el tema, los autores analizaron el comportamiento de un tanque de petróleo típico bajo la influencia de ondas explosivas. En ese caso se obtuvo la respuesta al evento considerando la distribución espacial de un pulso explosivo cuyo instante de inicio y duración era el mismo independientemente de la posición considerada...

This paper presents numerical results of stress concentration factors for plates perforated by corrosion. Evidence from 25 plates with corrosion perforation considered show that typical shapes may be characterized as a deviation from an ellipse or from a circle. In order to model typical perforations created by this type of corrosion, holes with no...

Teaching science and engineering is not what it used to be. At some stage, it was recognized that not all students learn everything in the same way: there are different learning styles. This new understanding of how people learn has been the subject of research in education, with the consequence that different learning styles are now emphasized as...

Wind-induced failure around screwed connections has been documented in roof and wall cladding systems made with steel sheet cold-formed panels during high wind events. Previous research has found that low cycle fatigue caused by stress concentration and fluctuating wind loads is responsible for most such failures. A dynamic load protocol was employ...

Palabras Clave: CFD, presiones, viento, tanques. Resumen. Una de las principales causas de falla estructural en los tanques de almacenamiento de líqui-dos de forma cilíndrica y baja altura se debe a la acción que el viento ejerce sobre ellos. En el diseño y optimización estructural de los mismos la información respecto de esfuerzos generados por pr...

Pressure coefficients in open canopy structures with parapets, such as those commonly used in gas stations, are presented. Two independent methodologies were used to obtain pressure coefficients: wind tunnel testing and Computational Fluid Dynamic (CFD) modeling. The experiments were performed in a low velocity atmospheric boundary layer wind tunne...

A dynamic load protocol has been used to experimentally simulate fatigue behavior in cold-formed metal panels with screwed connections under wind loading. The specific protocol adopted is an adaptation of SIDGERS, originally developed for non-metallic membranes, which is composed of levels each under increasing load values. A total of 19 tests were...

Experimental evidence indicates that the main damage mechanisms found in fibre-reinforced composites under static loading or environmental action are matrix damage, fibre damage, and interface damage, leading to various forms of strong inhomogeneities at the micromechanical level. The main objective of this paper is to identify the stress redistrib...

This paper presents a thermo-mechanical–microstructural formulation for the analysis of the solidification process of nodular cast irons of eutectic composition. This formulation is defined in a finite strain thermo-plasticity framework considering multinodular microstructure based liquid–solid phase change effects. The performance of this model is...

This paper reports computational results of an investigation of oil storage tanks with the shape of open cylindrical shell under thermal loads induced by fire. Interest in this problem arises as a consequence of a catastrophic fire that affected an oil storage facility in Puerto Rico in 2009, which produced failure of 21 large tanks. To identify pa...

A new numerical model to describe the microstructural evolution of a eutectic nodular cast iron during its cooling is presented. In particular, equiaxial solidification assuming an independent nucleation of austenite and graphite nodules is considered. In this context, the austenite has dendritic growth whereas the graphite grows with a spherical s...

This paper reviews the research on the theory of elastic stability published at the end of the XIX Century, with emphasis on the work by G. H. Bryan in Cambridge. The state of the studies on structural stability previous to Bryan is reviewed, and two lines of work are identified: one is a general stability of rigid bodies and the other is a collect...

The influence of topography on wind pressures acting on structures has been of interest to the civil engineering community for some time; however, because of the complexity of the problem, only few cases have been solved. The evaluation of pressures in tanks located in hills is one of those complex problems and has not been addressed in the literat...

The Reduced Stiffness Analysis (RSA) to compute lower bounds to buckling loads in shells was proposed by Croll in 1975. During the last thirty years, this methodology has been employed by a number of researchers as a simple way to evaluate the buckling capacity of shells that display unstable behavior and imperfection-sensitivity using simple eigen...

Several authors argued that history of science should be an integral part of science education; however, there are many obstacles to carry out an implementation within this approach, including that lecturers normally lack a necessary historical background (a situation that is largely aggravated in engineering faculties), and the impossi-bility of i...

Shell structures are usually designed by considering their final shape and configuration, so that it is assumed that stability during the construction will be satisfied without further thought. However, evidence from recent collapses of metal tanks under moderate winds shows that this is a matter that requires special attention. This paper reports...

This paper reports on the implementation of a lower-bound approach for the buckling of imperfection-sensitive shells using general purpose finite element codes. The stability of cylindrical steel tanks under wind pressure is evaluated for two tank configurations: conical roof tanks and open top tanks. For both tank configurations, several geometric...

En la formación actual de ingenieros generalmente se asocia el fenómeno de pandeo con el nombre de Leonard Euler, a quien se atribuye el descubrimiento del fenómeno. En este libro se examinan en forma crítica las contribuciones anteriores y posteriores a Euler, para identificar qué otros conceptos y conocimientos existieron antes de Euler y qué cam...

This paper presents an experimental and numerical study of the solidification process of ductile cast iron under slightly hypereutectic conditions. The material thermo-microstructural behaviour is measured in tests performed using standardized cups. Cooling curves at the centre of the cup were recorded, and metallographic studies were carried out t...

This paper reports results of the structural response of empty steel tanks under vertical ground motions. The tanks are modeled using a finite element discretization using shell elements, and the vertical motion is applied and analyzed using nonlinear dynamics. Several excitation frequencies are considered, with emphasis on those that may lead to r...

p. 114-126 This paper presents an overview of recent research aimed at understanding the behavior of aboveground steel tanks under wind loads, carried out by the author and by other researchers in this field. The tanks considered are representative of those constructed for the oil industry, with radius to thickness ratios of the order of 1500, and...

This paper presents a thermomicrostructural model for the simulation of the solidification process of an eutectic ductile cast iron. The thermal balance is written at a macroscopic level and takes into account both the structural component being cast and its mould. Models of nucleation and growth represent the evolution of the microstructure, and t...

Resumen: En este trabajo se propone una metodología de estimación de daño simplificada, basada en curvas de fragilidad, que tiene en cuenta las condiciones de exposición y las prácticas constructivas y de diseño locales, para edificaciones industriales construidas usando láminas y estructuras metálicas. Para este tipo de edificaciones se consideran...

Ground-supported steel tanks experienced extensive damage in past earthquakes. The failure of tanks in earthquakes may cause severe environmental damage and economic losses. This study deals with the evaluation of the elastic buckling of above-ground steel tanks anchored to the foundation due to seismic shaking. The proposed nonlinear static proced...