Reliability-based optimization of steel structures using genetic algorithms and nonlinear finite elements

Congreso celebrado en la Escuela de Arquitectura de la Universidad de Sevilla desde el 24 hasta el 26 de junio de 2015.Uncertainties are inherent in material properties, geometry parameters and loading in structural design problems. In a realistic design, it is necessary to consider these types of uncertainties to ensure safety and quality. Design constraints are formulated in probabilistic terms such as probability of failure or reliability index. The process of design optimization enhanced by the addition of reliability constraints is referred as Reliability-Based Design Optimization (RBDO). Most of RBDO methods use classical mathematical optimization algorithms and require the gradients of objective function and constraints. This task sometimes can be cumbersome and hard because reliability constraints are implicit functions of design variables. However, the increased power of computers has made possible to apply heuristic methods, especially Genetic Algorithms in RBDO problems. In this paper Genetic Algorithm is combined with OpenSees, a nonlinear Finite Element Reliability Analysis software, to salve RBDO problems. Two numerical examples show the performance of the implementation

Riesgo sísmico de la ciudad de Logroño

This paper contains part of the results obtained in the research project: “Resilient Logroño”. This work try to answer to the question: Is the city of Logroño prepared to face natural disasters? An especial treatment has posed in earthquakes because they are the most destructive disasters that can occur. This study deals with two aspects: seismic hazard and seismic vulnerability. In one hand, the earthquakes that have affected Logroño and its environment are described. In the other hand, existing buildings in the city are analysed to check if they are prepared to support a ground motion. Finally, the paper provides some previsions about building damages and human casualties that an earthquake with a macroseismic intensity of grade 6 could cause.Este artículo recoge parte de los resultados del proyecto de investigación “Logroño Resiliente”. Este trabajo trata de contestar a la pregunta: ¿Está la ciudad de Logroño preparada para hacer frente a desastres naturales? Se ha prestado una atención especial al riesgo sísmico ya que los terremotos son los fenómenos naturales más destructivos existentes. Este estudio se aborda en las dos vertientes que componen el riesgo sísmico: la peligrosidad sísmica y la vulnerabilidad de las edificaciones. Por un lado, se describen los sismos que han afectado a Logroño y su entorno. Por otro lado, se analiza la vulnerabilidad sísmica de los edificios existentes en Logroño. Finalmente, se dan algunas previsiones sobre daños en edificios y daños a la población que produciría un sismo con una intensidad macrosísmica de grado VI

Metodología eficiente de optimización de diseño basada en fiabilidad aplicada a estructuras

The main objective of this thesis is to analyze several Reliability-Based Design Optimization methods. These optimization techniques are applied to solving design problems where the cost function of a structure, like the weight or the volume must be minimized subject to probabilistic constraints written as limit state functions. Actions, material properties and geometric variables of the structural members are considered like random variables. These methods can be classified as double-loop methods, single loop methods and decoupled methods. A computer toolbox has been developed including procedures in the areas of structural analysis, structural reliability, design sensitivity analysis, mathematical programming and Monte Carlo simulation. The program solves both analytical problems and structural problems like plane and spatial structures. Computational efficiency, convergence, accuracy, generality and robustness of the methods have been discussed. Many options can be set by de user: displacement constraints, stress constraints and buckling constraints, prescribed reliability indices, distribution function for random variables, correlation coefficients between random variables, design sensitivity analysis methods. Probabilistic optimum designs are verified by Importance Sampling-based Monte Carlo Simulation.El principal objetivo de esta tesis es analizar el comportamiento de varios métodos de Optimización de Diseño Basada en Fiabilidad (RBDO), Estas técnicas de optimización se aplican a la solución de problemas de diseño de estructuras en los que hay que minimizar una función de coste, generalmente el peso o volumen de la estructura, sujeto al cumplimiento de unas restricciones probabilistas obtenidas a partir de los estados límite. Las acciones, propiedades del material, variables geométricas, etc. se consideran como variables aleatorias. Estos métodos se pueden clasificar como métodos de doble lazo, métodos de lazo único y métodos desacoplados. Estos métodos se han codificado en un programa informático que integra procedimientos de las áreas de análisis estructural, fiabilidad estructural, análisis de sensibilidad de diseño, programación matemática y simulación de Monte Carlo. El programa obtiene el diseño óptimo basado en fiabilidad en problemas analíticos y problemas estructurales: estructuras planas y espaciales utilizando diferentes métodos. Se han estudiado la eficiencia computacional, convergencia, exactitud, generalidad y robustez de los diferentes métodos (RBDO) analizados. El programa dispone de múltiples opciones configurables por el usuario. Por ejemplo: restricciones en desplazamientos, tensiones y pandeo, índices de fiabilidad objetivo para las restricciones, tipo de distribución de las variables aleatorias, dependencia entre las variables aleatorias, método de análisis de sensibilidad de diseño. Los resultados obtenidos se verifican mediante el método de Simulación de Monte Carlo con muestreo por importancia centrado en el punto de fallo más probable de cada restricción

Riesgo sísmico de la ciudad de Logroño

Este artículo recoge parte de los resultados del proyecto de investigación Logroño Resiliente. Este trabajo trata de contestar a la pregunta: ¿Está la ciudad de Logroño preparada para hacer frente a desastres naturales? Se ha prestado una atención especial al riesgo sísmico ya que los terremotos son los fenómenos naturales más destructivos existentes. Este estudio se aborda en las dos vertientes que componen el riesgo sísmico: la peligrosidad sísmica y la vulnerabilidad de las edificaciones. Por un lado, se describen los sismos que han afectado a Logroño y su entorno. Por otro lado, se analiza la vulnerabilidad sísmica de los edificios existentes en Logroño. Finalmente, se dan algunas previsiones sobre daños en edificios y daños a la población que produciría un sismo con una intensidad macrosísmica de grado VI.This paper contains part of the results obtained in the research project: Resilient Logroño. This work try to answer to the question: Is the city of Logroño prepared to face natural disasters? An especial treatment has posed in earthquakes because they are the most destructive disasters that can occur. This study deals with two aspects: seismic hazard and seismic vulnerability. In one hand, the earthquakes that have affected Logroño and its environment are described. In the other hand, existing buildings in the city are analysed to check if they are prepared to support a ground motion. Finally, the paper provides some previsions about building damages and human casualties that an earthquake with a macroseismic intensity of grade 6 could cause

Online learning environment tools in higher education : contributions to their integration in engineering courses

In order to understand the potential of Online Learning Environment tools and resources in Engineering Education, a project on the use of dedicated educational strategies has been carried-out in various European Schools of Engineering to improve students’ engagement on different forms of participation and to enhance their learning outcomes. This study focuses on the use of Web 2.0 tools while teaching Manufacturing Processes to Industrial Engineering students of a Higher Education Portuguese Polytechnic Institute during a full semester. Cumulatively to students’ perceptions, data was collected and assessed to infer about two main research questions: “Are engineering students able to use efficiently online learning tools to enhance their autonomous learning process?” and “Can engineering students work collaboratively using online tools towards achieving common learning goals?”. Preliminary findings showed that students managed to efficiently use the proposed online collaborative learning tools during the course. However, students preferred the individual learning tools and processes to working and learning collaboratively from and with each other.info:eu-repo/semantics/publishedVersio

Enhanced reconditioning of heavy-duty pulp industry equipment: advantages of abrasive waterjet cutting

Within a pulp industry production process, a drop in the performance of a wood log rotary debarker was identified. Such loss of performance was due to the occurrence of excessive wear of the device’s cutting blades, requiring their regular and premature replacement. The material used to manufacture the cutting blades, Hardox 500, has characteristics considered adequate for the required use. However, it was concluded that the blade manufacturing process degraded its mechanical properties, leading to its premature wear when placed in service. The present study intends to propose, characterize, and validate an alternative cutting process to manufacture the debarker’s cutting blades. Abrasive waterjet cutting technology was proposed to produce the cutting blades. The suitability of this manufacturing process is discussed considering the specified geometry and the material characteristics of the resulting cutting blades.info:eu-repo/semantics/publishedVersio